Table of Contents
TOPIC 051: SOFTWARE FUNDAMENTALS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
051.1 Software Components. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Lesson 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
What is Software? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Programming Languages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Programming Paradigms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Guided Exercises. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Explorational Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Answers to Guided Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Answers to Explorational Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
051.2 Software Architecture. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Lesson 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Servers and Clients . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Web Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Application Programming Interface (API) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Architecture Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Guided Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Explorational Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Answers to Guided Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Answers to Explorational Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
051.3 On-Premises and Cloud Computing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Lesson 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
On-Premises and Cloud Computing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
Common Cloud Operation Models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
Common Types of Cloud Services . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
Major Benefits and Risks of Cloud Computing and On-Premises IT Infrastructure. . . . . . . 42
Guided Exercises. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
Explorational Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
Answers to Guided Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
Answers to Explorational Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
TOPIC 052: OPEN SOURCE SOFTWARE LICENSES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
052.1 Concepts of Open Source Software Licenses. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

Lesson 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
Definitions of Open Source Software and Free Software. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
Free as in Speech: True Freedom for Users . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
Open Source Software . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
Freedom vs Open Source . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
Other Kinds of Monetarily Free Software . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
Principles of Copyright Law and How They Are Affected by Open Source Software
Licenses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
Principles of Patent Law . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
Licensing Contracts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
Derivative Works. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
Consequences of License Violations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
License Compatibility and Incompatibility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
Dual Licensing and Multiple Licenses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
Guided Exercises. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
Explorational Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
Answers to Guided Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
Answers to Explorational Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
052.2 Copyleft Software Licenses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
Lesson 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
Copyleft and the GNU General Public License (GPL) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
The GNU Affero General Public License (AGPL) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75
Compatibility of Copyleft Licenses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76
Combined and Derivative Works . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76
Weaker Copyleft . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77
Guided Exercises. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80
Explorational Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
Answers to Guided Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
Answers to Explorational Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
052.3 Permissive Software Licenses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
Lesson 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
Rights and Obligations of Permissive Software Licenses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88
Features of the Most Important Permissive Software Licenses . . . . . . . . . . . . . . . . . . . . . . . 88
Permissive Software Licenses in Relation to Other Open Source Licenses . . . . . . . . . . . . . . 92
Guided Exercises. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95

Explorational Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96
Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97
Answers to Guided Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98
Answers to Explorational Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100
TOPIC 053: OPEN CONTENT LICENSES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101
053.1 Concepts of Open Content Licenses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102
Lesson 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104
Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104
Copyright Fundamentals. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
Common Open Content Licenses Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107
Importance of Open Content Licenses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108
Trademarks and Copyrights . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108
Guided Exercises. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110
Explorational Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111
Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112
Answers to Guided Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113
Answers to Explorational Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114
053.2 Creative Commons Licenses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115
Lesson 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116
Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116
Origin and Goals of Creative Commons . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117
The Creative Commons License Modules. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117
The Creative Commons Core Licenses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119
Creative Commons Zero (CC0) and the Public Domain Mark . . . . . . . . . . . . . . . . . . . . . . . . 122
Selecting Licenses and Marking Works. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124
International and Ported Licenses. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126
Guided Exercises. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127
Explorational Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 128
Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129
Answers to Guided Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130
Answers to Explorational Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131
053.3 Other Open Content Licenses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132
Lesson 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133
Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133
Licenses for (Software) Documentation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133
Licenses for Databases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 134
Open Access . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139
Guided Exercises. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141
Explorational Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 142
Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143

Answers to Guided Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144
Answers to Explorational Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145
TOPIC 054: OPEN SOURCE BUSINESS MODELS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 146
054.1 Software Development Business Models. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147
Lesson 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 148
Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 148
Goals and Reasons to Release Software or Content Under an Open License . . . . . . . . . . 149
Common Business Models and Revenue Streams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150
Using Open Source Software in Other Technologies and Services . . . . . . . . . . . . . . . . . . . 152
Considerations of Open Source Software from a Customer’s Perspective . . . . . . . . . . . . . 153
Cost Structures and Investments. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153
Guided Exercises. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 155
Explorational Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 156
Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 157
Answers to Guided Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 158
Answers to Explorational Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 159
054.2 Service Provider Business Models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 160
Lesson 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 162
Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 162
Revenue Streams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 162
Impact of Licenses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165
Considerations of Security and Privacy Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165
Common Agreements Between Service Provider and Customer . . . . . . . . . . . . . . . . . . . . . 166
Cost Structures and Investments. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 168
Guided Exercises. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 169
Explorational Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 170
Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 171
Answers to Guided Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 172
Answers to Explorational Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 173
054.3 Compliance and Risk Mitigation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 174
Lesson 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 176
Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 176
Requirements for Releasing Software Based on Open Source Components . . . . . . . . . . . 176
Risks of Open Source Software . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 178
Software Bill of Materials: Know What You’re Using. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 181
Formal Policies and Compliance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183
Guided Exercises. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 186
Explorational Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 187
Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 188
Answers to Guided Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 189

Answers to Explorational Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 190
TOPIC 055: PROJECT MANAGEMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 191
055.1 Software Development Models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 192
Lesson 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 193
Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 193
Roles in Software Development . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 193
Planning and Scheduling. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 194
Common Tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 195
Waterfall Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 195
Agile Software Development, Scrum, and Kanban . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 198
DevOps. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 203
Guided Exercises. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 205
Explorational Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 206
Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 207
Answers to Guided Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 208
Answers to Explorational Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 209
055.2 Product Management / Release Management. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 210
Lesson 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 211
Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 211
Characteristics of Releases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 211
Software Versioning: Major, Minor, and Patches . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 214
The Software Product Lifecycle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 215
Documentation for Product Versions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 216
Guided Exercises. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 217
Explorational Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 218
Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 219
Answers to Guided Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 220
Answers to Explorational Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 221
055.3 Community Management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 222
Lesson 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 224
Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 224
Roles in Open Source Projects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 224
Common Tasks in Open Source Projects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 226
Kinds of Open Source Contributions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 227
Kinds of Open Source Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 227
The Role of Organizations in Open Source Projects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 228
Transfer of Rights . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 230
Rules and Policies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 230
Attribution and Transparency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 231
Diversity, Equity, Inclusivity, and Non-Discrimination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 231

Guided Exercises. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 233
Explorational Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 234
Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 235
Answers to Guided Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 236
Answers to Explorational Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 237
TOPIC 056: COLLABORATION AND COMMUNICATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 238
056.1 Development Tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 239
Lesson 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 241
Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 241
Goals of Development . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 241
General Development Processes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 242
Common Software Development Tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 245
Common Types of Software Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 249
Common Deployment Environments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 251
Guided Exercises. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 252
Explorational Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 253
Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 254
Answers to Guided Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 255
Answers to Explorational Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 256056.2 Source Code Management. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 257
Lesson 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 258
Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 258
Source Code Management System and Repository . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 259
Commits, Tags, and Branches . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 260
Subrespositories . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 261
General Use of a Source Control Management System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 262
Common Version Control Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 263
Guided Exercises. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 265
Explorational Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 266
Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 267
Answers to Guided Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 268
Answers to Explorational Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 269
056.3 Communication and Collaboration Tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 270
Lesson 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 272
Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 272
Ways to Communicate. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 273
Tools for Communication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 275
Tools for Collaboration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 279
Source Code Management (SCM) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 282
Documentation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 283

Guided Exercises. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 284
Explorational Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 285
Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 286
Answers to Guided Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 287
Answers to Explorational Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 288
Imprint. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 289

Open Source Essentials (Version 1.0) |Topic 051: Software Fundamentals

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Open Source Essentials (Version 1.0) | Topic 051: Software Fundamentals

051.1 Software Components
Reference to LPI objectives
Open Source Essentials version 1.0, Exam 050, Objective 051.1
Weight2
Key knowledge areas• Understanding the concept of source code and code execution• Understanding the concept of compilers and interpreters• Understanding the concept of software libraries
Partial list of the used files, terms and utilities• Source code
• Executable programs• Byte code
• Machine code
• Compiler• Linker• Interpreter• Runtime virtual machine• Algorithm• Software libraries• Static and dynamic linking

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Open Source Essentials (Version 1.0) | 051.1 Software Components

Lesson 1
Certificate:Open Source Essentials

Version:

1.0

Topic:

051 Software Fundamentals

Objective:

051.1 Software Components

Lesson:1 of 1Introduction
Free and open source software — often abbreviated as FOSS — has become an integral part of oureveryday lives, mostly without us being aware of it. FOSS, for example, can be found behind all of
our activities on the internet in some form: on the computer where we view web pages in thebrowser, or on servers that store these web pages and deliver them as soon as we call them up.

What is Software?
Before we look at all the specifics of free and open source software, however, we need to clarify
what software actually is. Let’s start with a very general description: Software is the non-physical,
immaterial part of computers in any form. Software ensures that the physical parts (thehardware) of the computer interact and that the computer can accept commands and executetasks.
A smartphone, a laptop, or a server in the data center is just a machine made of metal and plastic
when it is switched off. As soon as it is turned on, software starts up, in the form of codedcommand sequences that control the individual components of this machine, that allow the user
to interact with the machine, and that perform very specific tasks by invoking individual

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Open Source Essentials (Version 1.0) | Topic 051: Software Fundamentals

applications.
It is the work of software developers to analyze the tasks that the computer is supposed to perform
and to specify them in a way that allows the computer to implement them. The tools used by thedevelopers are as numerous and diverse as the tasks performed by the software.
Some software tasks are very closely connected to the hardware and the architecture of thecomputer, e.g., the addressing and management of memory or the handling of different processes.
System programmers therefore work close to the hardware.
Application developers, on the other hand, focus more on the user and program applications thatenable users to perform their tasks both efficiently and intuitively. An example of a complex
application is a word processing program that provides all the functions for text formatting inmenus or buttons and also displays the text as it might ultimately be printed.
In general, an algorithm is a way of solving a problem. For instance, to calculate an average, thenormal algorithm is to add a collection of values and divide the sum by the total number of values.
Although algorithms are traditionally designed and carried out by programmers, algorithms arealso generated nowadays by artificial intelligence.
The concepts in this chapter can help you understand the strengths and risks of FOSS, makeinformed choices, and even decide whether you want to be a software developer.

Programming Languages
Programming languages are highly structured, artificial languages that tell a computer what to do.
Programs are usually written in text, but some languages are written in graphical form. Softwaredevelopers write instructions (called code) to the computer in this artificial language. However,the computer hardware does not directly execute this code. Hardware can directly execute only aseries of bit patterns stored in memory, called machine code or machine language. All
programming languages are either converted into machine code by a compiler or interpreted byanother machine code program called an interpreter to make the hardware execute these
instructions.
Some of the most widely used programming languages currently include Python, JavaScript, C,
C++, Java, C#, Swift, and PHP. Each of these programming languages has its own unique strengths
and weaknesses, and the choice of language depends on the project and the needs of thedeveloper. For example, Java is a popular choice for developing large-scale enterpriseapplications, while Python is often used for scientific computing and data analysis.
Developers have shown impressive creativity in designing programming languages. Originally,
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become more and more high-level, meaning that they try to represent powerful combinations of
instructions is brief terms. Some languages reflect the way people naturally think, while
preserving the rigor necessary to run correctly.
About 400 programming languages are currently recognized, although many are used only in very
niche applications or legacy environments. Each was developed in order to solve in certain tasks.

Characteristics, Syntax, and Structure of Programming Languages
The choice of programming language can have a significant impact on performance, scalability,and ease of development in a software project. These sections lay out important elements oflanguages.
Characteristics of Programming Languages
Some of the common characteristics and qualities of programming languages include:
Concurrency
Concurrency denotes handling multiple tasks simultaneously, either by running on different
hardware processors or by alternating the tasks' use of a single processor. The degree ofconcurrency supported by a programming language can greatly affect its performance andscalability, especially for applications that require real-time processing or large amounts ofdata. Each separate piece of work might be called a process, a task, or a thread.
Memory management
Memory management is allocation and freeing of memory in a program. Depending on thelanguage or runtime environment, memory management can be done manually by the
programmer or handled automatically. Proper memory management is crucial for ensuringthat a program uses memory effectively, and that it does not run out of memory or cause otherproblems. If a program fails to free unused memory, the program causes a memory leak that
gradually increases the use of memory until the program crashes or negative performance
effects are noticeable.
Shared memory
Shared memory is a type of interprocess communication mechanism that enables multiple
processes to read and manipulate a common region of memory. Shared memory is common in
hardware such as disk drives, and can also be an efficient way to share data between
processes. But the mechanism requires careful synchronization and management to prevent
data corruption. An error known as a race condition occurs if one process makes anunanticipated change to data while another process is using it.

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Message passing
Message passing is a communication mechanism between processes that enables them toexchange data and coordinate their activities. This is commonly used in concurrent
programming to achieve interprocess communication, and can be implemented throughvarious mechanisms such as sockets, pipes, or message queues.
Garbage collection
Garbage collection is an automatic memory management technique used by some
programming languages to reclaim memory that is no longer being used while a process isrunning. This can help prevent memory leaks and make it easier for developers to write
correct and efficient code, but it can also introduce performance overhead and make control
over the precise behavior of the program more difficult.
Data types
Data types determine what type of information can be represented in the program. The datatypes can be predefined in the language or user-defined, and can include integers, floatingpoint numbers (i.e., approximations of real numbers), strings, arrays, and others.
Input and output (I/O)
Input and output are mechanisms for reading and writing data to and from a program. Input
can come from a variety of sources, such as user clicks and keyboard input, a file, or a network
connection, while output can be sent to a variety of destinations, such as a display, a file, or a
network connection. I/O allows programs to interact with the outside world and exchange
information with other systems.
Error handling
Error handling detects and responds to errors that occur during the execution of a program.
This includes errors such as division by zero and a requested file that is not found. Error
handling allows programs to continue running even when errors occur, improving theirreliability and robustness.
The concepts just listed are fundamental to understanding how programming languages work andhow to write efficient and maintainable code.
Syntax of Programming Languages
The syntax of a programming language refers to rules for writing program statements andexpressions. It is important for the syntax to be well-defined and consistent, so that the
programmer can effectively write and understand their code. The following are the building
blocks of most programming languages:

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Procedures and functions
Procedures and functions are used to define reusable blocks of code that can be called multiple
times.
Variables
Variables represent pieces of memory, and store data that can be manipulated and passed
between procedures and functions.
Operators
Operators are keywords or symbols (such as + and -) that assign values to variables andperform arithmetic operations.
Control structure
Generally, program code is executed in the order that it is written, but conditional statementschange the flow of execution. Which code is executed next is based on various conditions, suchas the contents of memory, the state of the keyboard, packets arriving from the network, and soon. The loop statement, a special form of conditional statement, is useful for performing thesame operations on a series of data sets. An exception, which invokes special code when anerror occurs, is another control structure.
The syntax and behavior of these constructs can vary between programming languages, and the
choice of language can have a big impact on the readability and maintainability of the code.
Libraries
A good programming language should make it easy to develop programs and easy to reuse
existing code. Many programming languages have a mechanism to organize procedures andfunctions into parts that can be reused in other programs.
A library is a collection of procedures and functions in support of a particular feature or goal,
combined into a single file. The availability of many easy-to-use libraries is another very
important requirement of a good programming language. For example, Python is widely
recognized as a good language for developing AI-related programs because it has a number oflibraries suitable for AI processing.
With the increasing size and complexity of programs, libraries as ready-made building blocks are
becoming more and more important. This is especially true in the open source world, where
people are comfortable taking code that others have created and reusing it. As a result, anecosystem of libraries has developed for each programming language, and package managers
such as composer for PHP, pip for Python, and gems for Ruby make it easy to install libraries.

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Libraries are also important compiled languages. Combining multiple binary files and precompiled libraries to obtain a single executable file is called linking, and the tool that performs
this operation is called a linker. There are two types of linking: static linking, in which only thenecessary library code is included in the final application’s executable file, and dynamic linking, inwhich a library installed in the system is shared by all applications that use that library.
Currently, dynamic linking is the preferred approach and is characterized by smaller application
executables and less memory usage at runtime.
Note that since the same libraries can be used by multiple programs, differences between versionsof a library can be even more of an issue than with applications. Let’s digress for a moment andremember how to look at version numbers. Semantic versioning is commonly used, whichindicates versions by three numbers separated by dots. A typical version might be 2.39.16,
which indicates a major version of 2 (a number that is likely to change only once every few years),a minor version of 39 within the major version (which may update every few months to contain
important feature changes), and a fast-moving revision of 16 (which can change because of asingle bug fix). Later versions and revisions have higher numbers.

A Very Simple Example
Let’s look at a very simple example of a computer program in the Python language to get a roughidea of a few of the elements mentioned.
Stated in natural language, the program is supposed to do the following: “Ask the user to enter anumber and check whether this number is even or odd. Finally, output the result.”
And here is the code we can save in the file simpleprogram.py:
num = int(input("Enter a number: "))if (num % 2) == 0:
print("The given number is EVEN.")else:
print("The given number is ODD.")

Even in these few lines of code, we can find many of the characteristics and syntax elements
mentioned above:
1. In line 1 we set the variable num and assign it a value with the = operator.
2. The assigned value corresponds to the input of the user (via the input() function ). In addition,
the int() function ensures that this input is converted to the integer data type, if possible. The
expression that is passed to a function within parentheses is called a parameter or argument.

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3. If the user enters a string of letters, Python would print an error as part of its error handling. If
a decimal number is entered, the function int() converts it to the base number, e.g. 5.73 to 5.
4. In the following lines, the control structure stating a condition, with the keywords if and else,
controls what happens in each of the two possible cases (the number is either even or odd).
5. First, the modulo operator tests whether (if) dividing the entered number by 2 yields the value
0 (i.e., no remainder) — in this case, the number is even. The doubled == is the “is equal to”
comparison operator, which is different from the assignment operator = in line 1.
6. In the other case (else), i.e. when the division by 2 produces a result unequal 0, the enterednumber must be odd.
7. In both cases, the function print() returns the result as output in text form.
And this is what it looks like when we run the program on the command line:$ python simpleprogram.py
Enter a number: 5
The given number is ODD.

When you consider how much language logic is already involved in this small example, you gain
an idea of what complex software distributed over thousands of files is capable of; for example,
operating systems such as Microsoft Windows, macOS, or Linux, which make all the hardware of acomputer available and at the same time ensure that the users can install all other desired
applications and use them for work or fun.

Machine Code, Assembly Language and Assemblers
As mentioned earlier, hardware can directly execute only a series of bit patterns called machinecode. The CPU reads a bit pattern from memory in units of a word (8 to 64 bits) and executes thecorrelating instruction. Individual instructions are quite simple, for example, “copy the contentsof memory location A to memory location B,” “multiply the contents of memory location C by thecontents of memory location D,” or “read the data that has arrived at the device at address X.” In
the era of 8-bit CPUs, some people could memorize all the bit patterns used in machine code andwrite programs directly. Nowadays, the number of instruction patterns has increased by an orderof magnitude, and trying to remember all of these patterns is impractical.
Machine code is a sequence of bit patterns, or 0s and 1s, which is not at all intuitive to humans. To
make programming more intuitive, assembly language was created, in which the instructions
were given names and could be specified by strings. In assembly language, instructions that
correspond one-to-one to the machine code are written one at a time. Instructions might look like:

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move[B], [A]copy the contents of memory A to memory B

multi

R1, [C], [D]multiply the contents of memory C by the contents of memory D

input

R1, [X]

read the data that has arrived at the device at address X

One instruction in assembly language corresponds to one instruction in machine code, whichcorresponds to the exact instruction that the hardware can understand and perform. Advantagesof assembly language over machine language include:
Improved readability and maintainability
Assembly language is much easier to read and write than machine code. This makes it easierfor programmers to understand, debug, and maintain their code.
Address computation automation
Machine code programming can also use the concept of variables and functions, but everything
must be expressed in terms of memory addresses. Assembly language also assigns names tomemory addresses, which makes it easier to express the logic of a program.
Because assembly language has access to all of the hardware’s functionality, it is commonly usedin the following situations:
Architecture dependent part of the operating system
Using dedicated instructions that are specific to one CPU architecture, for access toinitialization and security features, can be done only in assembly language.
Developing low-level system components
Assembly language is used to develop system components that need to interact directly withthe computer’s hardware, such as device drivers, firmware, and the basic input/output system(BIOS). In particular, high-speed devices that require pushing hardware performance to its
limits often need drivers and firmware programmed in assembly language.
Programming microcontrollers
Assembly language is also used to program microcontrollers, which are small, low-powered
computers used in a wide range of embedded systems from toys to industrial control. Somemicrocontrollers have memory capacities of just several hundred bytes, and are commonly
programmed in assembly language.
Assembly language code is converted to machine code before being executed by an application
called an assembler. The assembler is the oldest programming tool and has brought a number ofadvantages that were unthinkable in machine code programming. To confuse matters, sometimes
people refer to assembly language as assembler.

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Machine code and assembly language differ from one hardware processor to another. They arecalled “low-level languages” because they operate directly on hardware. However, the concepts ofcomputation and input/output are the same across all processors. If the common concepts can be
expressed in a way that is easier for humans to understand, programming efficiency can bedramatically improved. This is where “high-level languages” come in.

Compiled Languages
Compiled languages are programming languages that are translated either into machine code or
into an intermediate format called bytecode. Bytecode is executed on the target computer by aruntime virtual machine. The virtual machine translates the bytecode into the proper machinecode for each computer. Bytecode allows programs to be platform-agnostic and to run on any
system with a compatible virtual machine.
The translation of the source code written in a high-level programming language into machinecode or bytecode is done by a compiler. Examples of compiled languages that produce machinecode directly include C and C++. Languages that produce bytecode include Java and C#.
The choice between machine code and bytecode depends on the requirements of the project, suchas performance, platform agnosticism, and ease of development.

Interpreted Languages
Interpreted languages are programming languages that are executed by an interpreter, rather thanbeing compiled into machine code. The interpreter reads the source code and executes thestatements contained in it. An interpreter is able to directly process the source code, withouttransforming it into another file format. Thus, unlike a compiler, which translates the entire
program into machine code before executing it, an interpreter reads each line of code andexecutes it immediately, allowing the programmer to see the results of each line as they are
executed.
Interpreted languages are commonly used for scripting, which refers to short programs that
automate tasks, for command-line interfaces, and for batch and job control. Scripts written ininterpreted languages can be easily modified and executed without the need for recompilation,
making them well suited for tasks that require rapid prototyping or flexible and rapid iteration.
With this convenience come some potential drawbacks. For instance, an interpreted programruns more slowly than its equivalent compiled program, and the source code is accessible toanyone in possession of the script.
Examples of interpreted languages include Python, Ruby, and JavaScript. Python is widely used inscientific computing, data analysis, and machine learning, while Ruby is often used in web

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development and for creating automation scripts. JavaScript is a client-side scripting language
embedded in web browsers to create dynamic and interactive web pages.

Data-Oriented Languages
Data-oriented languages are programming languages that are optimized for processing andmanipulating large amounts of data. They are designed to efficiently handle large sets ofstructured or unstructured data and provide a set of tools for working with databases, data
structures, and algorithms for data processing and analysis.
Data-oriented languages are used in a variety of applications, including data science, big data
analytics, machine learning, and database programming. They are well suited for tasks thatinvolve processing and analyzing large amounts of data, such as data cleaning andtransformation, data visualization, and statistical modeling.
Examples of data-oriented languages include SQL (short for Structured Query Language), R, andMATLAB. SQL is a standard language used for managing relational databases and is widely usedin business and industry. R is a programming language and environment for statistical computing
and graphics and is widely used in data science and machine learning. MATLAB is a numericalcomputing environment and programming language used in a wide range of applications,
including signal processing, image processing, and computational finance.

Programming Paradigms
Besides the specifics of programming languages, programming paradigms determine theparticular solution approach. We can think of a paradigm as a basic strategy with which weapproach a task, depending on the specific requirements and conditions.
A comparable example is the construction of a house: Whether masons erect the walls brick bybrick or ready-cast concrete components are assembled on site is a fundamental decision that
depends on requirements and circumstances. What features do you want the house to have?
Where is it located? Is it connected to other houses?
In a similar way, paradigms set the direction of programming: whether and in what way, forexample, a software project is broken into smaller, separate parts. Each programming language issuited best to some particular paradigm. Therefore, the choice of paradigm is closely related to the
choice of programming language.
The following paradigms are common in programming:

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Object-oriented programming (OOP)OOP is based on the concept of objects, which are instances of classes that encapsulate data andbehavior. For instance, a language might offer a rectangle as a class to help the programmer
display a box on the screen.
OOP focuses on the object-level manipulation of data. OOP makes it easier to write code that ismaintainable, reusable, and extensible, and is widely used in desktop software, video games,
and web applications. Examples of object-oriented programming languages include Java, C#,
and Python.
Procedural programming
Procedural programming performs tasks through procedures, or blocks of code that can be
executed in a specific order. This makes it easy to write structured code that is easy to follow,
but can lead to code that is less flexible and harder to maintain as the size and complexity ofthe project grows. Examples of procedural programming languages include C, Pascal, andFortran.
Other approaches to software development are in use today, for which some languages are better
suited than others. Additionally, drag-and-drop interfaces allow non-programmers to write
programs, and many online services have recently started to generate code through artificial
intelligence when given plain-language instructions.
In conclusion, each programming paradigm has its own strengths and weaknesses, and the choiceof paradigm often depends on the needs of the project, the experience and preferences of thedeveloper, and the constraints of the platform and development environment. Understanding thedifferent types of paradigms can help you choose the right paradigm for your needs, and can also
help you write better and more efficient code.

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Guided Exercises
1. What is the purpose of functions?

2. What is the advantage of bytecode over a machine code file?

3. What is the advantage of a machine code file over bytecode?

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Explorational Exercises
1. What are some disadvantages of dividing a program into a large number of processes or tasks?

2. You have found several open source packages, offered in different versions, that provide
features you need for your program. What are some criteria for choosing a package?

3. In addition to OOP and procedural development paradigms, what other software development
approaches exist and what is a programming language which best supports each approach?

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Summary
In this lesson you have learned what software is and how it is developed with the help ofprogramming languages. The numerous programming languages differ not only in their syntax,
but also, for example, in their management of hardware resources or handling of data structures.
Programming languages also differ in how the source code, readable by humans, is converted byan interpreter or compiler into the final machine code to be processed by the computer.
Programming paradigms determine the strategy of software projects and thus also the choice ofsuitable programming languages, depending on the requirements and the size of the respective
project.

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Answers to Guided Exercises
1. What is the purpose of functions?
Functions encapsulate certain common activities, such as outputting a string. By making afunction, you can allow your program and other programs to perform the function
conveniently and repeatedly without having to write their own code for it.
2. What is the advantage of bytecode over a machine code file?
The bytecode file can run on many different computers, where a virtual machine turns thecode into machine code. For instance, JavaScript runs in many browsers on many types ofcomputers.
3. What is the advantage of a machine code file over bytecode?
Machine code runs as fast as possible. Bytecode runs more slowly because the virtual machinemust turn it into machine code while running the bytecode.

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Answers to Explorational Exercises
1. What are some disadvantages of dividing a program into a large number of processes or tasks?
When a program is divided into processes, they must communicate with each other. If theywork on a lot of data in common, the processes could expend a lot of overhead in dataexchange and in protecting data from multiple, simultaneous changes (race conditions).
Processes also incur overhead when they start up and terminate. The more processes you have,the more complex the program and its interactions become, so errors can be harder to find.
The functional paradigm tends to make it easier to divide programs into many processes,
because of immutability. Immutable data does not suffer from race conditions.
2. You have found several open source packages, offered in different versions, that provide
features you need for your program. What are some criteria for choosing a package?
Check bug reports and security advisories for the packages, because some are very buggy andeven unsafe. Sometimes the latest version is not the best, because a security flaw might havebeen introduced into it.
Peruse the forum where developers talk about the package, to see that it is actively maintained.
Your program will probably be in use for a long time, and you want the package to be available
and robust over time as well.
Try different packages to check their performance, as well as their correctness.
Most packages depend on functions found in other packages (dependencies), so a weakness in
one of the dependencies can affect your program.
3. In addition to OOP and procedural development paradigms, name some other softwaredevelopment approaches and a programming language that best supports each approach.
In addition to OOP and procedural development paradigms, other types include the following.
Functional programming emphasizes the use of functions and mathematical concepts, such as
lambdas and closures, to write code that is based on the evaluation of expressions rather thanthe execution of statements. Functional programming treats functions as first-classcitizens — so that they can be manipulated by the program — and emphasizes immutability, or
working with variables that cannot change after being initially set. This makes it easier toreason about and test code, as well as to write concurrent and parallel applications. Examplesof functional programming languages include Erlang, Haskell, Lisp, and Scheme.

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Imperative languages focus on the statements required to control the flow of the program’stransitions from and to various states.
Declarative languages describe what actions to take and the logic behind the instructions. The
order in which the instructions are carried out isn’t specified. These instructions, function calls,
and other statements can be reordered and optimized by compilers so long as they preserve
the underlying logic.
Natural programming is a programming paradigm that uses natural language or other humanfriendly representations to describe the desired behavior of a program. The idea is to makeprogramming accessible to people who may not have formal training in computer science.
Examples of natural programming languages include Scratch and Alice.

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051.2 Software Architecture
Reference to LPI objectives
Open Source Essentials version 1.0, Exam 050, Objective 051.2
Weight2
Key knowledge areas• Understanding the concepts of client and server computing• Understanding the concepts of thin and fat clients• Understanding the concepts of monoliths and microservices and their main differences• Understanding the concepts of Application Programming Interfaces (APIs)• Understanding the concept of software components and their integration or separation(services, modules, APIs)
Partial list of the used files, terms and utilities• Clients and servers• Thin clients and fat clients• Web applications• Single-page applications• Monolithic architectures• Microservice architectures• Application Programming Interfaces (APIs)• RESTful APIs

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Lesson 1
Certificate:Open Source Essentials

Version:

1.0

Topic:

051 Software Fundamentals

Objective:

051.2 Software Architecture

Lesson:1 of 1Introduction
The internet is ubiquitous in our modern world, as are mobile and web-based applications. These
tools are used seamlessly by a large portion of the world’s population and power everything frominstant messaging to more complex activities like purchasing mining equipment for large
companies.
Behind all these seemingly simple interfaces and online services is an architecture — anarrangement of cooperating pieces of software — that we often take for granted. You need toknow a bit about this architecture to understand how all the pieces of the internet fit together andhow software can deliver real value to its users.
In this lesson, we will look at some of the software architectures behind web applications, which
are server-based software systems, and how they are used within systems that almost everyone isfamiliar with.

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Servers and Clients
When you use online systems, it is highly likely that at some point you have encountered amessage like the one in Sample screen shown while a response is underway.

Figure 1. Sample screen shown while a response is underway

Let’s step back a little bit and look at the context in which you’re seeing this message. Say you aretrying to gain access to your banking account through your bank website. When you try to get
onto the banking website on your laptop, you use a type of software (i.e., application) called a web
browser, such as Google Chrome or Firefox. In this case, the browser on your computer sends arequest to another computer hosting the website. This particular kind of computer is called aserver. It is specially designed to run 24/7, always serving new requests coming in from all parts of
the world.
So a server is a computer, just like the one you use to work with, play video games, and do
programming assignments. However, there is one main difference: A server normally uses all its
resources for the software application running on it. In this example, the software is a web
application, a computer program that runs on the server.
In Sample screen shown while a response is underway, the server has received a request from abrowser, and the application running on the server is processing the resulting operation. This
operating could be querying a database to fetch a user’s details in the bank, or communicatingwith another server to verify a special discount on the user’s next loan.

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In this example, we call the browser running on your machine the client application, or simply
put, the client. The client interacts with the remote server.
The network communication between client and server might take place inside an enterprisenetwork, or across the worldwide network we call the internet. A common characteristic of clientserver interaction is that a server can establish multiple relationships with multiple clients. Think
about the previous example: the website of a bank hosted on a server can attend thousands ofrequests per minute from multiple locations, each with a user trying to access their personal bankaccount.
Not all scenarios are structured like a browser interacting with a server that does almost all theprocessing. In some cases, the client can be the primary instance for processing; this concept iscalled a fat client (or thick client), where the client stores and processes the majority of the tasks
instead of relying on the server’s resources. In our banking example, in contrast, the browser is athin client that relies on the server to compute and return information through the network.
An example of a fat client is a video game desktop application, where the bulk of the data storage
and processing is done locally, using the computer’s GPU, RAM, CPU, and disk space to process theinformation. Such an application rarely relies on an external server, especially if the game isbeing played offline.
Both approaches have pros and cons: For a thick client, network instability is less of an issuecompared with a thin client that relies on a remote server, but software updates can be harder toapply and the fat client requires more computer resources. For a thin client, the lower costs could
be a great advantage. For either kind of client, providing personal data to a third-party application
can be an issue.

Web Applications
A web application is software that runs on a server, processes user interactions, and is contacted
by either fat or thin clients through a computer network. Not all websites are considered web
applications: Simple static web pages without interactivity are not considered web applications
because the server doesn’t run an application to process actions requested by the client.
A lot of web applications can be divided into two groups: the single page application (SPA) and themulti-page application (MPA). An SPA has only one web page, where all data exchange and loading
occur without the need for redirecting the user to another web page inside the application. An
MPA, in contrast with the SPA, has multiple web pages. A data change might either refresh thesame web page that originated the action or redirect the user to another web page.
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transactions on the internet banking website. Imagine that a transaction happens after the web
page is loaded. If the bank web application is an SPA, the new transaction will be displayed
automatically on the same web page, without redirecting the user to a new page. If the user
checks their loans, the new information is also displayed on the same page, avoiding the need toredirect the user to a new web page. Altering the page without redirecting the user makes thenavigation smooth.
For an MPA, when the user requests the loan web page, the server must redirect the user to a newlocation, which means another web page.
A famous example of an SPA web application is Google Mail (Gmail). It doesn’t redirect the user tocompletely new page when, for example, the user wants to display the the spam folder; theapplication merely refreshes the specific part of the display that shows all spam messages, andstays on the same web page.
On the other hand, a famous MPA application is Amazon.com, the ecommerce giant, where each
item is located on a distinct web page.
One advantage of an MPA over an SPA is that web analytics are much easier to gather andmeasure. This is crucial to help the developers optimize internet search results.
Usually, a web application is divided into two separate parts: frontend and backend. The frontend
is the view layer, where the user interacts with a browser using the page elements by clicking,selecting, or typing. This is where the data from the server is received, formatted, and displayed tothe user through the browser.
The backend is generally the larger part of a web application. It comprises the business logic,
communication handlers, the majority of the data processing, and the data storage. Data storage
employs a separate database management system connected to the backend.
The frontend and backend communicate with each other. Data requests are forwarded by thefrontend to the backend, and the data returned by the backend is received, formatted, anddisplayed by the frontend to the user.
In our simple example of fetching the latest transaction in a user’s bank account, the action isinterpreted by the frontend of the application, which is running in the browser on the user’s
desktop. This request is then sent through the internet to the backend of the application, which
validates whether the user is allowed to perform the action, fetches the data, and returns the listof transactions back to the frontend loaded in the browser. The browser then formats anddisplays the data to the user.

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Application Programming Interface (API)No software is useful without communicating with internal and external components. So how can
the client communicate with the web application? How can the frontend send data to thebackend?
Software applications communicate with each other via an application programming interface(API), running over basic internet communication protocols. Protocols are standards and rules
developed to ensure that two or more applications exchange commands and data.
The main benefit of an API is to decouple different parts of application while allowing them tocooperate in processing data. APIs also centralize the data flow in pre-defined channels, acting
like a gateway that ensures that everyone uses the same way for coming and going. In web
applications, APIs are vital for the application’s functionality, as they allow user interaction, thedelivery of processed information, requests for data storage, and many other tasks. An API can beused by the client to request actions that will be executed on the server, for example.
Let’s go back to the banking web application example. To log into an account through a web
application, the user generally types data such as username and password into certain text fields
and clicks a “Login” button. The browser grabs this information and calls a backend API. The web
application running on the remote server receives the user data, validates the user, verifies theright of the user to gain access, and finally sends a response back to the browser. In order for theuser to communicate with the server, it is mandatory for both client and server to send data backand forth. That is what APIs enable.
Notice that the bank’s web application does not expose other sensitive information; it shows theuser only the fields that are allowed and necessary for a desired interaction. The rest is hiddenfrom the user.
Communication between APIs can be based on very different designs and protocols. The hypertext
transfer protocol (HTTP) is by far the most frequently used protocol in web applications. Hypertext
is text with links to other texts, the concept underlying the links in HTML web pages. Hyperlinks
thus form the basis for constructing web pages and displaying them in browsers.
HTTP was designed for client-server applications, where the resources are requested from aserver and then returned to the client over the network using a predefined structure specified by
the HTTP protocol.
For a structured web application, software engineers design the application with separate parts or
modules. This separation of responsibility allows clearly defined tasks and responsibilities,
leading to faster development and better maintenance.

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Let’s take, as an example, an application with two internal modules: one that implements thebusiness logic, and the other relying on a third-party integration. This third party is an external
company that provides its API for some specific purpose — weather forecasting, say. If theweather server is down, it is impossible to get weather details, and if this data is crucial to thefinal processed output, the user might experience some temporary headaches if there is noalternative source for the data.
Now imagine that this third-party provider is replaced and the new one has a different way ofhandling the same API. The separation of modules means that developers of only one module
have to update it. The business logic in the other module doesn’t have to be touched at all, or atleast calls for minimal updates.
The need for clear process structures also influences the design of the APIs in order to make themeasier to use. The representational state transfer (REST) concept is an architectural style with a setof guidelines for designing and implementing access to data in an application.
There are six REST principles. For the sake of simplicity, we are going to explain three that are
most relevant to this lesson:
Client-server decoupling
The client should know only the resource URI, through which communication with the server
occurs. This principle allows greater flexibility. For example, when the backend side of theapplication is refactored, or there is a major architectural change to a backend database, thefrontend does not need to be updated in conjunction. It simply continues to send the same
HTTP requests to the backend.
Statelessness
Each new request is independent from the previous ones. It is no coincidence that the HTTP
protocol is widely used for applications that follow REST principles, since HTTP has noknowledge of previous HTTP requests; for each new request, all the necessary informationmust be sent in order to correctly process the request. For example, a web application that
implements this principle has no knowledge whether the client is logged in (authenticated). So
for each HTTP request, the client must send an authentication token. The server can use thistoken to verify whether the request should be blocked or processed.
One of the main advantages of this principle is easier scaling, because the server can process
millions of requests without checking user details.
Layered architecture
The application is composed of multiple layers, and each layer can have its own logic andpurpose, such as security or data acquisition. The client may never know how many layers

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exists, or whether they are communicating directly with a specific layer inside the application.
APIs following the REST principles are called RESTful, and in the modern web, the REST design isfollowed by many web applications. Although a RESTful API does not need to implement theseprinciples using the HTTP protocol, it is almost universally used in the REST model given its
robustness, simplicity, and ubiquitousness in the world wide web environment.

Architecture Types
Dozens of architectural styles and standards exist that attempt to organize the structures of web
applications, Like almost everything in the computer world, there is no “winner,” only a set ofpros and cons for each model. An important paradigm is the so-called microservice architecture,that was created as an alternative to the older monolithic architecture.
The microservice architecture is a software model composed of multiple interdependent services
that together form the final application. This architecture aims to decentralize the codebase:Multiple layers of software are split into multiple smaller applications for better maintenance(Microservice architecture).

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Figure 2. Microservice architecture

In contrast, a monolithic architecture contains all services and resources of the application in one
application (Monolithic architecture).

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Figure 3. Monolithic architecture

The images show that the microservice model is decentralized and the application relies on
multiple services, each with its own database, codebase, and even server resources. As the nameimplies, each microservice should be smaller than its monolithic counterpart, which takes
responsibility for all services.
The monolithic application encapsulates all its resources into one single unit. All the businesslogic, data, and codebase are centralized in one huge block, which is why it’s called a “monolith.”
Users hardly notice whether a web application is running as a monolithic or microservice model;
the choice should be transparent. Our banking application, for example, could be a monolith
where all the business logic regarding payments, transactions, loans, etc. is located in the samecodebase running on one or more servers. On the other hand, if the banking appliction uses a
microservice style, it probably has a microservice dedicated to processing payments and anothermicroservice just for issuing loans. The latter microservice calls yet another microservice toanalyze the probability that the applicant will default on the payment. The application could have

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thousands of smaller services.
The monolithic approach requires more maintenance overhead when the application grows
larger, especially with multiple teams coding in the same codebase. Given the centralized software
resources, it is highly likely for one team to change something that breaks the another team’s partof the application. This could be a real headache for larger teams, especially when there is a great
number of teams.
Microservices are much more flexible in that regard, because each service is managed by only one
team. One team can, of course, manage more than one service. The code changes are easily done
and competing resources are not a real issue. Since each service is interconnected, any point of
failure could have a negative impact on the entire application. Furthermore, since there are
multiple database instances, servers, and external APIs communicating with each other, theresilience of the whole application is only as good as its weakest microservice.
One advantage of the monolithic approach is having one centralized data source, which makes it
easier to avoid data duplication. The approach also reduces the consumption of cloud resources,
because one larger server needs fewer computer resources than multiple decentralized servers. A
microservice application of roughly the same size puts a greater burden on the cloud.

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Guided Exercises
1. What are the main differences between a fat and a thin client?

2. Is it correct to assume that every website is a web application?

3. What is the REST model?

4. What is the preferred model for developing large and modern web applications with multiple
development teams? Why?

5. What is the most commonly used protocol to exchange data between web applications?

6. Name two disadvantages of multi-page applications compared to single-page applications.

7. Describe one advantage of a monolithic system over a microservice system, and one advantage
the microservice system has compared to a monolithic one.

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Explorational Exercises
1. In 2021 the NASA Perseverance Rover landed on Mars, with one of its goals to determine
whether life ever existed on Mars. Although the Rover could be controlled by distance here on
Earth, it also can control itself in most situations. Why is it a good idea to project a rover likethat as a fat client?

2. Consider a modern, self-driving, personal car that connects to an external server to exchange
data. Should it be a fat or a thin client?

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SummaryThis lesson explained the core concepts of software architecture for web applications. The lesson
explained how they are commonly structured and organized, and the main differences between
the monolithic and microservice models. We covered the concepts of servers and clients, and thebasics of web application communication between clients and other software programs.

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Answers to Guided Exercises
1. What are the main differences between a fat and a thin client?
A fat client does not require a constant connection to a remote server that gives back criticalinformation to the running client. The thin client relies heavily on the information processedby an external source. Another difference is that a fat client is responsible for the bulk of thedata processing, thus requiring more computing resources than its thin counterpart.
2. Is it correct to assume that every website is a web application?
No. There are websites that are not software applications. A web application interacts with theuser, who might input data and use web functionalities in real time. Simple websites such as anadvertisement for a social event, which functions like a web banner, are not web applications.
These non-interactive web sites are easier to maintain and require tiny computing resources tohost and deliver the web pages. A web application requires much more computing resources,more robust servers, and functionalities that handle users, such as restricted access andpermanent data storage.
3. What is the REST model?
The REST model is a software architecture model providing applications with a development
guide for better usability, clarity, and maintainability. One of the principles outlined in the setof REST guidelines is the layered architecture, used primarily for cohesion and to lower the
dependency of the various APIs' internal components.
4. What is the preferred model for developing large and modern web applications with multiple
development teams? Why?
The microservice software model provides a flexible framework in which teams collaborate on
the same software application, providing easier concurrency for two or more teams
maintaining a large web application. Because the framework is decentralized, each team canupdate a specific business domain without having to update other components.
5. What is the most commonly used protocol to exchange data between web applications?
HTTP is the most used protocol for exchanging data and commands between servers andclients.
6. Name two disadvantages of multi-page applications compared to single-page applications.
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actions, instead of updating only the changed elements. Performance suffers from this design.
Another disadvantage of an MPA is clunkier user interactivity, where each page load creates aloss in user friendliness. In contrast, the visual effect could be continuous in an SPA.
7. Describe one advantage of a monolithic system over a microservice system, and one advantage
the microservice system has compared to a monolithic one.
A monolithic system can make data administration easier because the data is located in one big
database, instead of being scattered in multiple databases. A microservice application, on theother hand, can improve code development and maintenance; multiple teams can work on
different business logic without blocking the progress of other teams.

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Answers to Explorational Exercises
1. In 2021, the NASA Perseverance Rover landed on Mars. One of its goals was to determine
whether life ever existed on Mars. Although the Rover can be controlled over a long distance byan application on Earth, it also can control itself in most situations. Why is it a good idea todesign a rover like that as a fat client?
The time a communication signal takes to be sent from Earth and received on Mars can varydepending on the positions of those planets, but it can take up to twenty minutes. Thus,
command and control of a distant rover in motion is impossible, especially taking unexpected
situations into account. Ideally, the rover should command itself in most situations. That isachieved using artificial intelligence (AI) training (machine learning), so that the rover
becomes more independent from manual commands. To make that possible and to rely less on
distant signals, the rover was projected to have its own resources and the majority of thecomputing processes ran locally, matching the definition of a fat client.
2. Consider a modern, self-driving, personal car that connects to an external server to exchange
data. Should it be a fat or a thin client?
An autonomous vehicle could delegate the heavy data processing to an external and reliable
server, but this would be susceptible to offline periods when critical data processing isrequired. Therefore, it is imperative for the autonomous vehicle to process the majority oftasks — and this requires it to be a fat client with multiple redundancy.

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051.3 On-Premises and Cloud Computing
Reference to LPI objectives
Open Source Essentials version 1.0, Exam 050, Objective 051.3
Weight1
Key knowledge areas• Understanding the concepts of on-premise and cloud computing• Understanding common cloud operation models• Understanding common types of cloud services• Understanding the major benefits and risks of cloud computing and on-premise IT
infrastructure
Partial list of the used files, terms and utilities• Cloud computing• On-premises IT infrastructure• Data center• Public, private and hybrid cloud• Infrastructure as a Service (IaaS), Platform as a Service (PaaS), Software as a Service (SaaS)• Cost models• Security• Data ownership• Service availability

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Lesson 1
Certificate:Open Source Essentials

Version:

1.0

Topic:

051 Software Fundamentals

Objective:

051.3 On-Premises and Cloud Computing

Lesson:1 of 1Introduction
Everyone is talking about the cloud nowadays. Businesses are evaluating services from a range ofvendors — including major companies such as Amazon.com and Microsoft — to see what the cloud
can offer.
But the idea of cloud computing goes back only to the late 2000 decade. And the term is a vague
one — so vague that many people, including the Free Software Foundation, discourage the use of
the term.
However, the idea of cloud computing embodies some specific useful concepts, and is a crucial
trend in modern computing. This lesson looks at what the cloud is and, at a high level, how it
works both technically and financially. We’ll look at benefits and risks of the cloud. Along the way,
we’ll see why this topic is related to open source.

On-Premises and Cloud Computing
If you work or study in an organization that has more than a couple computer systems, it almost
certainly has a data center: a separate room to hold the organization’s servers, usually locked and38|

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air-conditioned. An on-premises (or on-premise) data center is simply one that the organization
maintains for its own use.
There are several alternatives to running a data center on-premises. For decades before the trend
we call “cloud computing,” businesses would set up data centers that hosted computers on behalfof clients. Thus, you might license five servers from the business, and give the business various
specifications for CPU, memory, and storage, and then upload your software to the servers. Thisbusiness model is remote hosting.
Remote hosting offers many advantages. The organization can effectively outsource theadministrative expertise of buying and setting up servers to the remote hosting business, which
could get bulk purchases. In other words, you avoid the responsibility of having an on-premises IT
infrastructure. The remote hosting business ensures physical security, also freeing the client fromthat worry. Finally, setting up a new server on a remote hosting business is much faster thanbuying, shipping, and setting up the server on-premises.
An organization can also maintain an on-premises data center while licensing more servers in the
remote environment to recover from disasters or provide extra compute power during periods ofheavy use.
Note that remote computing assumes the presence of a fast and reliable network. We’ll explore
this issue along with other benefits and weaknesses in another section.
All the advantages of remote hosting apply also to cloud computing. Cloud computing istechnically different because no particular physical computer is devoted to your organization.
Instead the cloud vendor runs multiple systems for multiple clients on each physical system, using
an extra layer of software known as virtual machines.
Thus, a cloud service runs a data center like any other organization, but serves otherorganizations instead of (or in addition to) itself. The data center stores thousands of physicalcomputers. On each physical computer it runs an operating system (usually called a hypervisor)
that supports multiple virtual machines. Each virtual machine can be spawned and deleted
quickly. Each virtual machine supports one operating system run by a client (Cloud computing).

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Figure 4. Cloud computing

Where does free software and open source come in? When a business is running huge numbers ofcomputers and deploying operating systems on the fly, it’s important not to get bogged down
dealing with licenses. Although there are licensing models for proprietary operating systems in
the cloud, they are more complicated than simply running an open source virtual machine andoperating system. Open source is usually cost-free, too.
The beginning of cloud computing is usually traced to Amazon.com’s launch of Amazon Web
Services (AWS) in 2006. There are now dozens of cloud companies, including offerings from such
big vendors as Microsoft, Google, Alibaba, and IBM. AWS is still the largest offering. The vendors
compete fiercely on developing new features and services, because they are all strong on cost andreliability.
The advantages of cloud computing build on those of remote computing. Costs are lower because
one physical system can run many servers for many clients, and can be kept busy constantly. A
client that needs more computing power quickly for a spike in usage can spawn new systems inseconds. The systems can be managed automatically through an application programming
interface (API). Again, we’ll take a closer look at benefits and risks later.

Common Cloud Operation Models
Before detailing operation models, it’s worth noting that many companies have adopted cloudmodels that totally change their way of programming and offering services. Instead of updatingeach application once or twice a year, the companies allow rapid updates. They can do thisbecause the cloud allows them to shut down virtual machines and start up new ones almost

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instantly with the new version of the application. The organization can also scale up and down
quickly, so they like to break applications into many modular parts, sometimes calledmicroservices.
But in this section we’ll focus on everyday cloud models.
The cost model for the cloud is very different from on-premises costs. On-premises data centersrequire the one-time purchase of a server, along with routine costs for power, air conditioning,
and administration. These disappear when you license systems from a cloud vendor. Instead, you
are charged for what you use. Cloud vendors divide your computer usage into time periods andcharge you for each period. They also charge by the amount of data you store on their systems.
So far, we’ve been talking about vendors who offer compute power to customers; this is called the
public cloud. But there can also be a private cloud. Some large organizations run their own onpremises data centers like a cloud. They provide services only to their own departments or
subdivisions, but they treat each of their departments like a client of a cloud vendor. The data
center keeps track of how much compute time, data, etc. is used by each department and charge it
for that usage.
Many organizations use multiple cloud services for various reasons, such as to protect against
vendor failures, keep data in a certain geographic region, or take advantage of special featuresoffered by a particular vendor. In addition, it’s common to maintain both an on-premises data
center and servers in the cloud, a practice called hybrid computing.
A client who signs up for a cloud service can choose which geographic regions to run in. For
instance, Amazon curently offers regions in the US West, US East, several regions in Europe, andmore regions in every part of the world. Normally, you’d choose the region closest to you. But
many organizations want to operate in multiple regions because they are international in scope.
The organizations sometimes need to keep data in a particular place to adhere to Europe’s
General Data Protection Regulation (GDPR), or China’s Personal Information Protection Law(PIPL).
Each region normally is further subdivided into zones or availability zones. Running in multiple
zones is recommended in case a disaster causes one zone to go down.
Although the cloud is notable for sharing physical computers among multiple clients, some
vendors can devote a single computer to a particular client who is worried about security.
Because no other organization is using the computer, the client feels a bit safer running their
sensitive services and uploading their data to the cloud. This option brings cloud computing closer
to old-fashioned remote hosting.

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Common Types of Cloud Services
At different levels, cloud computing looks very different and is aimed at different types of users.
Infrastructure as a Service (IaaS) is the category that system administrators usually deal with. IaaS
provides just hardware and the software that supports virtual machines. It’s up to systemadministrators of the client to load an operating system and their desired applications onto thevirtual machine. The system administrator handles nearly everything the same way as on an onpremises data center.
Platform as a Service (PaaS) is a more recent invention, used mostly by programmers. Here, theprogrammer doesn’t worry about the operating system and doesn’t have to load the libraries thatthe program uses. All of that is provided by the cloud vendor. The programmer just uploads
functions that run on the platform. A related concept is serverless computing.
Software as a Service (SaaS) is an application running on a cloud system. Every time you log into asocial media site, order an item from an online store, visit a web page to enter your hours into a
job tracking system, or enter a form on a government site, you are using SaaS. The bulk of theapplication is running on the remote system, and the only part of the application running on yourcomputer is the web page displayed by your browser.
Database as a Service (DaaS) is often added to the preceding categories. A data service, Amazon’s
S3, was actually the first cloud offering. A DaaS offering can simply be an instance of a popular
database server such as MySQL, Oracle, or MongoDB running in the cloud. Big cloud vendors alsooffer propriety databases that run only in their cloud offerings. In any case, you read and write
the database as if you had it on your systems.
Other variations on those basic categories are offered by some companies, such as Security as aService.

Major Benefits and Risks of Cloud Computing and On-Premises
IT Infrastructure
Before examining cloud computing in detail, let’s try an analogy. Running an on-premises data
center is like buying a house. If the basement floods or the boiler stops working, you need to findsomeone to fix it. In contrast, remote hosting and cloud computing are like renting an apartment:
The landlord is responsible for fixing the boiler. Furthermore, in the cloud you can quickly add
and remove data loads, just as you can change apartments more quickly than you can change
which house you own.
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like the numerous services that cloud providers offer, such as databases and analytics.
Now we can look at the benefits and risks of using the cloud, instead of or in addition to your own
data center.
Flexibility is probably the most compelling reason to move to the cloud. If you’re a retailer who
needs to run more servers near Christmas, or a tax preparation accountant doing most of yourbusiness at tax season, you’ll want the cloud in order to spin up new servers at a moment’s noticeand then delete their virtual machines later.
Costs can be lower in the cloud for several reasons. You are sharing a physical server with manyother applications, so the computers are used more efficiently. Because cloud vendors are large,
they can achieve economies of scale in purchases, administration, cooling, and otherinfrastructure requirements. Finally, the clients are freed from many administrative
tasks—although system administration is by no means going away. Clients still need systemadministrators to create and upload their software (known as instances in the cloud), to authorize
users, and other tasks related to business operations. System administrators have to learn thevendor’s API and the rules for using the service, a training cost you should factor into your plans.
On the other hand, you have to be careful how much use you make of the cloud. It can be hard to
keep track of how much computer power you’re using when you can quickly spin servers up,
especially if you automate your scaling. You might find an unpleasantly large bill at the end of theperiod.
Is the cloud more carbon-efficient than running our own computers? Research finds that cloudvendors can run their systems much more efficiently than you or I can. But we have tocommunicate with those systems over a network, which requires a lot of electrity to power all the
networking equipment. So unfortunately the cloud increases our carbon footprint.
Service availability is sometimes better with the cloud. Certainly, if you depend on your own onpremises data center, you are vulnerable to all kinds of problems ranging from natural disasters
to malicious internal saboteurs. But data centers in the cloud also go down. So you should takeadvantage of the different availability zones and spread out your risk. There are tools that allow
you to switch your services from a failed zone to a working one.
If you use the services offered by the cloud vendor, such as a database in the cloud, you arevulnerable to bugs in that service. Of course, you can also suffer from bugs in the software you
load into your system.
A greater risk in using vendors' services is lock-in. You can usually find an automated conversion
tool to move your data out of the vendor’s system and into a new one, but the tool might not do acomplete job.

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Security can be better in the cloud because the vendor’s staff are probably more expert than yoursecurity staff. On the other hand, cloud vendors are big and well-known, furnishing obvious
targets for attack. Also, adding an extra piece of software -— the hypervisor that controls thevirtual machines -— introduces a new potential hazard. Researchers have found vulnerabilities inhypervisors.
Although the client remains the legal owner of its data, storing the data in the cloud theoreticallyleaves it more vulnerable. Usually, the client encrypts the data to protect it in case of a break-in.
Privacy regulations, such as the previously mentioned GDPR, require data to be stored in a data
center in a region considered to be safe.
Ultimately, most security attacks start at a high level, such as sending email with malware to anunsuspecting employee. It doesn’t matter whether you’re running on-premises or in the cloud. But
a malicious intruder who takes over an employee’s account will not get much farther unless they
can take advantage of vulnerabilities in your servers; again it’s not clear whether running in thecloud makes much difference because most vulnerabilities are found in the software rather thanthe cloud service.
Finally, consider your bandwidth and networking costs. Your customers, and probably your staff,
are communicating with servers that might be hundreds of miles away. If the network connecting
is unreliable or slow, the performance of cloud servers will be worse than your on-premises data
center. But nowadays, everybody is connecting with remote workers, SaaS services, and othersystems that are geographically removed. Your network performance will affect nearly
everything you do, whether or not you’re in the cloud.

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Guided Exercises
1. Why is a physical computer in a cloud center used more efficiently than a computer in a
traditional on-premises data center?

2. What is a hybrid cloud?

3. What type of cloud computing most often requires work on the part of a system administrator
at the client side?

4. How should you protect your service from going down if you use a cloud vendor?

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Explorational Exercises
1. Compare the different kinds of costs you experience when running your servers in a cloud tothe costs of running them on-premises.

2. You operate out of the Middle East, but have many customers in Europe and the Far East.
Describe where you would place your services in a cloud offering.

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SummaryThis lesson outlined how cloud computing works and the trade-offs of using the cloud versus
running systems in your own data center, on-premises. You learned different business and costmodels, including the differences between public, private, and hybrid clouds. You also learned thedifferent major types of cloud offerings and what each is used for.

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Answers to Guided Exercises
1. Why is a physical computer in a cloud center used more efficiently than a computer in a
traditional on-premises data center?
In the cloud, each computer can run multiple instances of operating systems, and even run
instances uploaded by different clients. Therefore, the computer is more often in use.
2. What is a hybrid cloud?
A hybrid cloud uses both data centers at a cloud vendor and one or more on-premises data
centers.
3. What type of cloud computing most often requires work on the part of a system administrator
at the client side?
Infrastructure as a Service (IaaS) requires the client to perform system administration for tasks
such as creating and uploading instances of the operating system and applications.
4. How should you protect your service from going down if you use a cloud vendor?
Choose several zones in each region where you run your service, because it’s highly unlikelythat many zones will fail simultaneously.

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Answers to Explorational Exercises
1. Compare the different kinds of costs you experience when running your servers in a cloud tothe costs of running them on-premises.
In a cloud, you pay for your CPU use and data storage for each period measured by the vendor.
But you don’t pay any hardware costs. On-premises, you have the fixed cost of the hardware,
along with other equipment such as air conditioning, plus recurring costs such as power andphysical maintenance.
2. You operate out of the Middle East, but have many customers in Europe and the Far East.
Describe where you would place your services in a cloud offering.
Use a Middle Eastern region for your own offices and Middle Eastern clients. A region in
Europe is important in order to comply with the General Data Protection Regulation (GDPR).
You might need a region in China to comply with China’s Personal Information Protection Law(PIPL). In any case, having Far Eastern and European regions is valuable for better
performance when interacting with customers in those places.
Within each region, choose several zones to protect against the failure of a single zone.

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Topic 052: Open Source Software Licenses

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052.1 Concepts of Open Source Software Licenses
Reference to LPI objectives
Open Source Essentials version 1.0, Exam 050, Objective 052.1
Weight3
Key knowledge areas• Understanding the definitions of open source software and free software• Awareness of other kinds of monetarily-free software• Awareness of important events in the history of open source• Understanding what a license is and what rights licenses commonly manage• Understanding how existing software can be used to create derivative works• Understanding license compatibilities and incompatibilities• Understanding dual licensing and conditional licensing• Understanding consequences of license violations• Understanding the principles of copyright law and patent law and how they are affected byopen source software licenses
Partial list of the used files, terms and utilities• Free Software Foundation (FSF) free software definition• Open Source Initiative (OSI) open source software definition• Licenses• Contracts• Public domain software
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Open Source Essentials (Version 1.0) | Topic 052: Open Source Software Licenses• Freeware• Shareware• License stewards• Permissions to use, modify and distribute code and software• Derivative works and code reuse• Closed source / proprietary software• Paid distribution• Modified and unmodified software distribution• Hosting software as a paid service• License compatibility• Dual and multi licensing• Conditional licensing• Software patents• Explicit and implicit patent license grants

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Lesson 1
Certificate:Open Source Essentials

Version:

1.0

Topic:

052 Open Source Software Licenses

Objective:

052.1 Concepts of Open Source Software
Licenses

Lesson:1 of 1Introduction
Any software developer appreciates when a problem has been efficiently solved before. If thesolution is available online, the understandable reflex is to try it out: to copy or link the existingsource code into one’s own code base, test it, and leave it there if it works — and then to forget
about it.
But some caution is in order. More often than not, software source code available on the internet
is covered by a free and open source (FOSS) license. This chapter will go into some basic concepts
of FOSS from a legal standpoint and why it is a good idea to not take FOSS source code for granted,
but rather to closely observe the licensing conditions.
As a basis for understanding your legal obligations in software, understand that a license governs
almost all software. A license is a kind of contract. All software, including web sites, should be
distributed with a written version of its license (often called “terms and conditions”). Some
programs and web sites make you check a box saying that you have read their terms andconditions (and you should, although most people never do). In any case, you implicitly accept thelicense by using the software.

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Definitions of Open Source Software and Free Software
Free and open source software has been around for quite some time, and the terms are often seen
together. However, there is some discrepancy between what some declare to be “free software”
and the formal meaning of free software, as well as open source software. Spoiler: “Open source”
does not just mean that anyone can look at the source code — that would be “source available”
software. Free and open source software is much more than that.
Free and open source software is contrasted with other kinds that are considered proprietary or
closed source because they don’t offer all the freedoms discussed in this lesson.
Perhaps the most cited definition of free software is:
Think of “free speech,” not “free beer.”— Richard Stallman, Selling Free Software

We’ll unpack the fertile brew in that statement during the following sections.

Free as in Speech: True Freedom for Users
On the one hand, developers can decide to simply forego the rewards and difficulties of selling
their software, and just give it away without compensation. In English this software is “free” in thesense that no one has to pay for it, but free only like beer that is given away. This no-cost
distribution says nothing about further licensing conditions, and leaves the user with the
obligation to always take a closer look: They might not have been granted the necessary rights tochange or further distribute the software, for example.
On the other hand, developers can opt to make their software “free software” in Stallman’s sense.
This term (which he coined in the 1980s) refers to the user’s essential freedoms summarized asfollows:
1. To run the software
2. To study it
3. To give it to others (redistribute it)
4. To redistribute copies of the modified versions“Free software” in this definition is championed by the Free Software Foundation (FSF) which
introduced the term copyleft (which has no legal meaning, but presents a philosophicalconsideration) to characterize the license on free software.

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Open Source Software
Out of the free software movement, open source advocates arose in the late 1990s as a way tomake free software easier to understand and more popular among people outside the movement.
A nonprofit foundation, the Open Source Initiative (OSI), was founded in 1998, and Linus Torvalds,
initial author of the Linux kernel, gave his support to the concept. The Open Source Initiative
formalized the Open Source Definition to include the following criteria:
1. Free redistribution: One is free to decide how to redistribute the program, whether cost-free orfor sale, so long as no royalty or license fee is demanded. This freedom includes incorporating
the program into another program.
2. Source code availability, be it online or provided along with the software.
3. Allowing the creation and distribution of derived works and modifications.
4. Integrity of the author’s source code: Modifications can be restricted if recipients are allowed tomodify the program through patches at build time and to distribute these patches along withthe source code. The distribution of software built from modified source code may not be
restricted.
5. No discrimination against persons or groups: For instance, a license with permission for use of
the software by “teachers only” would not satisfy the Open Source Definition.
6. No discriminations against fields of endeavour: For instance, do not restrict commercial use.
7. Distribution of license: Everyone who receives the program has the same, original license.
8. License must not be specific to a product.
9. License must not restrict other software: For instance, other software bundled with thissoftware could have a different license.
10. License must be technology-neutral.

Freedom vs Open Source
The Free Software Foundation did not endorse the term “open source,” insisting that it hides the
key goal of freedom. Thus, while advocates of free software and open source software seem to be
pursuing and advocating for the same concept, the movements have separate motivations. Statedin a simplified form, free software advocates emphasize the rights of developers and users,
whereas open source advocates prioritize the software’s widespread use and success.
Pretty much all free software qualifies as open source, while there are many licenses that areconsidered to be open source (as approved by OSI) but are not free according to the FSF.

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Because the differences between free and open source concern goals and motivations more thanthe content of the licenses, and since both terms remain in frequent use, many advocates refer toboth definitions together using the phrases free and open source software (FOSS) or free/libre andopen source software (FLOSS). The term “libre” refers to freedom in many Romance languages.

Other Kinds of Monetarily Free Software
In addition to the broad categories of FOSS and proprietary software, a range of other distribution
strategies exist. Some of these strategies are:SharewareThis term generally refers to proprietary software that is for sale, but can be used for free withlimited functionality until the user decides to buy the full version.
FreewareThis term describes software that is distributed free of cost and without limitation on use, but
not necessarily in comformance with a formal definition of the free software. Freeware inmany cases is proprietary and the source code is often not released at all.
Source available software
Sometimes the developers of proprietary software make their source code available (tofacilitate better bug reports, for instance), but impose acquisition of a proprietary license as acondition on the use of the source code in other projects. This kind of availability with strict
limitations should not be confused with actual open source software.
Shared source softwareThis term was introduced by Microsoft in 2001, when the company decided to make some of
their software source code available online for research and testing. Don’t confuse this narrow
definition with shareware or source available software.
Public-domain softwareThis is software on which the authors have waived all copyrights. This definition does not
apply in all jurisdictions (especially with those where the author is granted rights of “droit
d’auteur” or “author’s rights,” as in France or Germany). Licenses such as the “Unlicense” havebeen introduced, which are meant to have the same effect. Moreover, software may also enter
the public domain when the duration of copyright has expired.

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Principles of Copyright Law and How They Are Affected by Open
Source Software Licenses
First and foremost: If there is no license information available for a certain source code file orproject, you cannot assume that the file or project lacks copyright protection. Indeed, the contraryis the case, at least since most nations worldwide signed the Berne Convention since 1887.
In this treaty, the signatory nations agree that a literary or artistic work is protected by copyright
as soon as it exists (or in other words, as soon as it is “fixed” into a medium). That means that an
author does not have to register or apply for copyright. They still can do so in some countries, andregistration might be necessary for infringement actions in some jurisdictions including the US.
Also, the signatories agree to respect the copyright of any author of another signatory country,
which, as of November 2022, amounted to 181 of the 195 countries in the world.
However, not everything ever created is copyright protected. In order to qualify as a work
protected by copyright, the creation needs to satisfy some basic criteria: For example, facts andideas cannot be protected by copyright, but a text explaining an idea may be protected if itreaches a certain degree of originality. The measure of originality differs around the world, but inmany cases, the barrier for protection is very low. Many jurisdictions are currently considering
how much artificial intelligence can be used to create a work deserving of originality and hence
copyright.
Depending on the jurisdiction, computer programs are protected by copyright as literary works:That is, copyright does not apply to the idea or algorithm but to its implementation in source code.
Copyright gives the author the exclusive rights (among others) to copy, modify, sublicense,
distribute, and publish the work. Reception of the work is free, so one does not need a license toread a book or to listen to a song on the radio, as long as doing so does not require making apermanent copy.
Because the author’s rights come into being without the need for registration, anyone who wants
to copy, modify, sublicense, distribute, or publish the work of another author has to get
permission first. This is where licenses come into play, as contracts between the author of a workand a person who wants to exercise some of the exclusive rights of the author.
FOSS licenses are offered to anyone without a fee. Anyone can create their own license and try to
get it approved by the OSI or FSF. But using an existing FOSS license is highly recommended
because of their general acceptance and the familiarity that knowledgeable software users havewith the contents of the license and its obligations. In fact, only a handful of the many licenses
approved by the FSF or OSI are in common use.

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Principles of Patent Law
In contrast to copyright, which does not protect ideas, patents protect inventions (ideas) without
the need for the idea to be fixed (yet) in a machine or process. A further difference is thatinventors must apply for patents explicitly and register them with the patent office of the country
where protection is sought.
Without diving too deeply into patent law and its requirements, we’ll just point out a very central
issue: Patent protection requires (among other criteria) an idea with a certain technical aspect.
Historically, the ideas for a new meal recipe or a new board game do not qualify for patent
protection, whereas the ideas for a new cooking machine or a game console might qualify.
In the context of computer programming, the question arises whether software could be subject topatent protection. This depends on both the legal jurisdiction and the particular application: For
example, in Germany, computer programs as such are generally excluded from patent protection.
However, if programs are combined with a physical object — e.g., when software controls an
automated braking system in a car — patent protection can be sought for the application including
the physical element of the brake and not the software as such, and might therefore qualify.
In other jurisdictions, such as the US, patents may be granted for computer programs as such,depending on case law developments.
The concept of patent protection should be kept in mind in FOSS licensing. Some licenses (such as
the GPLv3) allow patents on the FOSS software by explicitly granting permission for the software’suse. But some licenses do not even mention patents (such as the BSD-3-Clause license) and yetother licenses explicitly exclude them (such as the Creative Commons licenses). However, undercertain circumstances, patent grants may be implied by the license or may be read into thelicense.
NOTE

The different FOSS licenses are covered in subsequent lessons.

Especially when dealing with embedded software, such as software in audio devices, special
attention should be paid to patents connected with the software, e.g. by conducting patent checks
on authors of the software.

Licensing Contracts
As mentioned before, licenses are contracts between the author of a work and someone whowants to excercise some of the exclusive rights of the author. Some of the more extensive FOSS
licenses, such as the GNU General Public Licenses version 2 and version 3, include provisions forcontract termination. FOSS licenses always include rights grants regarding the central freedoms.

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Usually, the following rights are stated or can be read into the license text:…the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
the Software…
— MIT license

License stewards are persons or, in many cases, organizations such as the FSF, who manage
versions of the licenses. For example, section 9 of GPLv2 declares the FSF to be the license
steward:
The Free Software Foundation may publish revised and/or new versions of the General
Public License from time to time. Such new versions will be similar in spirit to the present
version, but may differ in detail to address new problems or concerns.
— GNU General Public License version 2

Some license stewards also publish frequently asked questions (FAQs) to help answer questions
regarding the licenses. These can be useful as a conversation starter between licensee andlicensor.

Distribution
Distribution of software (in binary or source code form, in particular) is a central aspect of most
FOSS licenses, since mere use of FOSS software usually does not trigger any licensing obligations:
Activities other than copying, distribution and modification are not covered by this License;
they are outside its scope. The act of running the Program is not restricted…
— GNU General Public License version 2

Most licensing obligations arise only with distribution, i.e., passing on a modified or unmodified
copy, be it on a tangible medium such as a CD or via download. In some cases, licensing conditions
are also triggered if software is running on a server (i.e., without ever distributing the sourcecode) while the user interacts with the software.
Distribution of executable software might require the delivery of the source code, license text, andcopyright notices as well, depending on the FOSS license type. Some licenses require modification
notices to be put in the source code if modified code is being distributed.
Distribution could also trigger copyleft effects; i.e., upon distribution of GPLv3 licensed softwarethat has been modified, the source code of the entire modified software may have to be released
under the GPLv3.

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While FOSS may be sold, usually no licensing fees may be imposed. This means, for instance, thatsomeone can sell software under the GPLv3 license as just a binary, but since the source code isavailable (or has to be offered), people interested in the software can always opt to obtain thesources (perhaps from somebody else, for free) and to build the software from the sources.

Derivative Works
When one set of developers incorporate code into their own project from someone else’s project,
the result might be a derivate or derived work. The details vary from one project to another andfrom one license to another, and because the details require some sophistication with softwaredevelopment techniques, we’ll just say that the developers have to make sure they areincorporating the code in a way that conforms to the license.
The most important issue regarding derivative works is that, for some licenses such as the GPL, aderivative work must be released under the same license. Such licenses are called reciprocal.
The immediate practical significance of a reciprocal requirement is that, if you use GPL’d code inyour own project in a way that makes yours a derivation, you have to reveal your source code andlet others build products on it. This licensing requirement is highly desired by some developers
who want to encourage more people to use free licenses. However, the license reduces the appealof the GPL for some developers who might potentially use free code.
Many other free and open source licenses do not impose that requirement. These tend to be called
permissive licenses.

Consequences of License Violations
If, at the time of distribution, licensing conditions are not met (e.g., if GPLv3 licensed software
distributed as a binary is not accompanied by an offer of source code), the licensing contract isviolated. The consequences of licensing violations depend on the license. Violation of the GPLv3
license, for example, may lead to termination of the license. Any further actions that require
permission by the author, e.g. distribution of the software, then constitute copyright violations.
If a company includes GPLv3 licensed software in a product and violates the license, a claim may
be filed requiring the company to recall their products. Intentional copyright violations can evenlead to criminal charges.
Some licenses have specific clauses allowing the licensee to fix the violation within 30 days of
notification. If the person distributing the software manages to comply with the license within thisperiod, the license is reinstated.

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License Compatibility and Incompatibility
Large software projects often include software under different licenses, each license specifying its
individual requirements. Such projects can come up against hurdles using software that requires
its license to be used on derivative works. This is because the licensing terms of such copyleftlicenses may differ, rendering them incompatible. Publishing or distributing a software projectthat integrates components under different copyleft licenses might not be possible without
violating one of the licenses.
Some copyleft licenses explicitly list compatible licenses making it easier to use a copyleft-licensed
component under another copyleft license.
Most permissive licenses are compatible with other licenses. For instance, MIT-licensed
components may be used in a GPLv3 licensed project without risking licensing violations.
However, a GPLv3 licensed component may not in every case be used in a MIT licensed project
without violating the terms of the GPLv3. Compatibility might therefore not always work both
ways.
Before a software project is put into the market, developers and their legal advisors should
conduct a thorough license compatibility check, to avoid running into licensing violations. Open
source compliance management should be integrated into the early stages of a softwaredevelopment process to avoid delays in software distribution caused for example by license
incompatibility issues. Search the source code thoroughly for applicable licenses (e.g., by using
software scan tools) and check whether all licensing conditions are met.

Dual Licensing and Multiple Licenses
Some software may be available under several licenses. For example, a licensor may choose todual license their project under both a copyleft license such as the GPLv3 and a proprietary
license. The proprietary license might be required, for instance, if the potential licensee
incorporates the code into their own proprietary product. Each developer determines whether
they can adhere to the GPLv3 conditions or must obtain the proprietary license, and most likely
entail a licensing fee.
As pointed out earlier, some software may include components under various licenses withdiffering licensing conditions. Although most licenses do not often cause incompatibility, different
licenses may come with different requirements for different parts of the software.

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Guided Exercises
1. What does the acronym FOSS stand for?

2. Which of the following explicitly belong to the user’s essential freedoms for free software?
Run software
Study software
Copy software
Change software
Publish software
Redistribute software
3. Is source code found on the internet with no licensing information free for modification anddistribution by anyone? Please explain.

4. Can software be patented?
Yes
No
It depends
5. What is a license steward?
The same as a licensor
Someone who may propose future versions ofa license
Someone who may terminate a license
Someone who manages software of airplanes
6. Does license compatibility always work both ways?

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Yes, if two licenses are compatible, it does notmatter whether A is included in B or B is
included in A.
No, in some cases license A may be included ina project under license B, but B may not beallowed to be distributed under license A.
No, license compatibility is always
unidirectional.

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Explorational Exercises
1. Are the GPLv2 and the LGPLv2.1 license compatible? Please give a short explanation.

2. Can software be published under Open Content licenses (such as CC-BY)?
Yes, CC licenses can be applied to any
copyrightable work.
No, software may only be protected bypatents.
No, CC licenses do not apply to software.
3. Why is distribution important in the context of FOSS licensing?

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SummaryThis lesson provides an introduction to the basic concepts of free and open source software aswell as the underlying concepts of copyright and patents. It explains some of the foundations andhistory of both free software and open source software and helps distinguish both of those fromproprietary licensing concepts. The Open Source Definition by the OSI helps categorize licenses as
open source licenses.
While dozens of FOSS licenses already exist, anyone is free to introduce additional licenses.
The concept of licensing is not to be underestimated: Licenses provide permissions to deal with
software in ways otherwise reserved exclusively to the author. Breaches of licenses can result in
legal disputes. Legal advice regarding license compliance should therefore be sought before
software is distributed or incorporated into other project code.

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Answers to Guided Exercises
1. What does the acronym FOSS stand for?
Free and Open Source Software
2. Which of the following explicitly belong to the user’s essential freedoms for free software?
Run software

X

Study software

X

Copy software
Change software

X

Publish software
Redistribute softwareX

3. Is source code found on the internet with no licensing information free for modification anddistribution by anyone? Please explain.
No. Source code, if it reaches the threshold of originality, is by default copyright protected as aliterary work. Since modification and distribution constitute exclusive rights of the author, no
one but the author may do so or give permission to do so.
4. Can software be patented?
Yes
No
It depends

X

5. What is a license steward?
The same as a licensor
Someone who may propose future versions of X
a license
Someone who may terminate a license
Someone who manages software of airplanes
6. Does license compatibility always work both ways?

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Yes, if two licenses are compatible, it does notmatter whether A is included in B or B
included in A.
No, in some cases license A may be included in X
a project under license B, but B may not beallowed to be distributed under license A.
No, license compatibility is always
unidirectional.

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Answers to Explorational Exercises
1. Are the GPLv2 and the LGPLv2.1 license compatible? Please give a short explanation.
If software A is licensed under the GPLv2 and software B is licensed under the LGPLv2.1, it ispossible to use B in A, since LGPLv2.1 allows for use under the conditions of the GPLv2 license.
However, A cannot be used in B under the terms of the LGPLv2.1. If A is being used in B, theentire software has to be licensed under the GPLv2, which is possible, because LGPLv2.1 allows
for the software’s use under the GPLv2.0.
2. Can software be published under Open Content licenses (such as CC-BY)?
Yes, CC licenses can be applied to any
copyrightable work.

X

No, software may only be protected bypatents.
No, CC licenses do not apply to software.
3. Why is distribution important in the context of FOSS licensing?
Many FOSS license obligations are triggered upon distribution of the software. If software isnever distributed, but only changed and used in a closed system (such as a division of acompany), it may be possible to use the software without adhering to the licensing obligations.

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052.2 Copyleft Software Licenses
Reference to LPI objectives
Open Source Essentials version 1.0, Exam 050, Objective 052.2
Weight3
Key knowledge areas• Understanding the concept of copyleft software licenses• Understanding the rights granted by copyleft software licenses• Understanding the obligations created by copyleft software licenses• Understanding the main properties of common copyleft software licenses• Understanding the compatibility of copyleft software licenses with other software licenses• Awareness of the terms “reciprocal license” and “restrictive license”
Partial list of the used files, terms and utilities• Copyleft• Distributing• Conveying• Tivoization• GNU General Public License, version 2.0 (GPLv2)• GNU General Public License, version 3.0 (GPLv3)• GNU Lesser General Public License, Version 2 (LGPLv2)• GNU Lesser General Public License, Version 3 (LGPLv3)

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Open Source Essentials (Version 1.0) | Topic 052: Open Source Software Licenses• GNU Affero General Public License, Version 3 (AGPLv3)• Eclipse Public License (EPL), version 1.0• Eclipse Public License (EPL), version 2.0• Mozilla Public Licence (MPL)70|

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Lesson 1
Certificate:Open Source Essentials

Version:

1.0

Topic:

052 Open Source Software Licenses

Objective:

052.2 Copyleft Software Licenses

Lesson:1 of 1Introduction
The importance of licenses for both the use and the development of software has already been
described. It is therefore not surprising that free software has also been characterized by new
approaches to licensing from the outset: Conditions for the unrestricted use or collaborative
development of software must be legally defined in order to be protected and enforced.
Aware that copyright law, which is firmly anchored in almost all legal systems worldwide, could
not be questioned or replaced, software developers took an approach as early as the 1980s that
respects copyright regulations but supplements them with new regulations that emphasize theprinciple of “freedom”: copyleft.

Copyleft and the GNU General Public License (GPL)Richard Stallman, then a developer at the renowned MIT, founded the GNU Project in 1983 todevelop what he considered to be a “free” operating system. It soon became clear that the codedeveloped by the project had to be legally protected so that it could not simply be taken over bycommercial providers and thus become “non-free.”Version: 2024-07-26|

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Stallman therefore founded the non-profit Free Software Foundation (FSF) in 1985, whichsummarizes its mission on its website as follows: “The Free Software Foundation is working tosecure freedom for computer users by promoting the development and use of free (as in freedom)
software and documentation…”
A key instrument for this mission is a license that respects applicable law (especially copyrightlaw) on the one hand and implements its own ideas of freedom in a legally clean manner on theother. The result was the first version of the GNU General Public License (GPLv1) in 1989. Thislicense and numerous articles — such as “What is Free Software?”, written by Stallman in
1992 — make clear the motivations and values of free software developers, who now also seethemselves as a “movement.”
The programmatic core is still formed by the “four essential freedoms” formulated by Stallman in
the aforementioned article, the numbering of which begins with 0:• The freedom to run the program as you wish, for any purpose (freedom 0).
• The freedom to study how the program works, and change it so it does your computing as
you wish (freedom 1). Access to the source code is a precondition for this.
• The freedom to redistribute copies so you can help others (freedom 2).
• The freedom to distribute copies of your modified versions to others (freedom 3). By doing
this you can give the whole community a chance to benefit from your changes. Access tothe source code is a precondition for this.
— Richard Stallman, What is Free Software?

Unlike licenses for commercial products, which place restrictions on use in the foreground, free
software is about maximum freedom for users and developers.
The preamble of the GNU GPLv1 summarizes this as follows:
Specifically, the General Public License is designed to make sure that you have the freedom
to give away or sell copies of free software, that you receive source code or can get it if you
want it, that you can change the software or use pieces of it in new free programs; and thatyou know you can do these things.
— GNU General Public License, version 1

This means that everyone has the right to use, distribute, and modify software under the GPL
without restriction (which is possible because the source code is accessible, i.e. “open”) and inturn to distribute the modifications. It is even possible to charge money for passing on thesoftware:72|

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Actually, we encourage people who redistribute free software to charge as much as they wish
or can. If a license does not permit users to make copies and sell them, it is a nonfree
license….Free programs are sometimes distributed gratis, and sometimes for a substantial
price. Often the same program is available in both ways from different places. The programis free regardless of the price, because users have freedom in using it.
— Free Software Foundation, Selling Free Software

But if the freedoms are so far-reaching, to what extent is software protected under this license, forexample from being incorporated into proprietary products?
This is the role of the previously mentioned copyleft principle, which the GPL already applies inversion 1 even if the term does not yet appear explicitly:
You may not copy, modify, sublicense, distribute or transfer the Program except as expressly
provided under this General Public License.
— GNU General Public License version 1

This means that all these freedoms are linked to the condition that users preserve these freedoms
in everything they do with the software.
Copyleft therefore not only guarantees freedoms, but also requires all users to grant these
freedoms to others. This is achieved by stipulating that software under a copyleft license (such as
the early GPLv1) may be modified and redistributed only if the modifications are published under
the same conditions, i.e. under the same license.
The ideal of free software, namely the collective use and further development of software,
therefore takes precedence over the personal needs that individuals might have in relation to thesoftware. The principle of reciprocity is crucial: Those who use freedoms must also grant them.
Copyleft licenses are therefore often referred to as reciprocal.
This completely new approach to a software license already proved to be legally sound andpracticable in version 1 of the GPL, so the GPL has undergone only two major revisions in thealmost 40 years during which the modern IT market has developed.

GPLv2 and GPLv3
In 1991, the Free Software Foundation presented version 2 of the GNU General Public License(GPLv2), which established itself as the most popular license for free software projects over many
years. For example, the core of the Linux operating system is still licensed under GPLv2 today.
Compared to version 1, version 2 is primarily concerned with more precise definitions to avoid

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ambiguities. For example, version 2 explains in much greater detail what is meant by “sourcecode.”
Also of interest is the new Section 7, which sets the principle of freedom and thus the validity of
the license as absolute and does not allow any compromises — for example, the integration of lessfree parts into the software:
If you cannot distribute so as to satisfy simultaneously your obligations under this License
and any other pertinent obligations, then as a consequence you may not distribute theProgram at all. For example, if a patent license would not permit royalty-free redistributionof the Program by all those who receive copies directly or indirectly through you, then the
only way you could satisfy both it and this License would be to refrain entirely from
distribution of the Program.
— GNU General Public License version 2

It was not until 16 years later, in 2007, that the FSF published a new version of the GPL in order totake account of technical innovations — such as the provision of software services via theinternet — as well as issues of compatibility with other FOSS licenses. However, the license
remains stable in terms of its core statements and merely adds details for further clarification.
Let’s take a closer look at some of these additions.
While the GPLv2 still generally refers to the provision of software as distribution, GPLv3 specifies
this process with two new terms: propagation and conveying. The main reason for this is that theterm “distribution” is defined in numerous copyright laws worldwide. To avoid ambiguity or
conflict, the GPLv3 chooses these new terms and defines them as follows:
To “propagate” a work means to do anything with it that, without permission, would makeyou directly or secondarily liable for infringement under applicable copyright law, except
executing it on a computer or modifying a private copy. Propagation includes copying,
distribution (with or without modification), making available to the public, and in somecountries other activities as well.
To “convey” a work means any kind of propagation that enables other parties to make or
receive copies. Mere interaction with a user through a computer network, with no transfer ofa copy, is not conveying.
— GNU General Public License version 3

With the significantly growing number of commercial software products whose distribution isrestricted by manufacturers through technical measures such as registration codes or hardware
components (so-called dongles), there were a number of international legal initiatives in the late
1990s to criminalize the circumvention of these measures. This so-called digital rights
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management (DRM), also derogatorily referred to by opponents as digital restrictions management,
is a thorn in the side of the FSF, as the measures fundamentally contradict the demand for the free
distribution of software.
In response, version 3 of the GPL contains a passage stating that software under the GPL may not
be modified with reference to legal DRM requirements. This also means that software licensed
under GPLv3 may use DRM, but that others are also permitted to circumvent such measures.
The term tivoization is also frequently used in this context. The word appeared explicitly in thefirst drafts of GPLv3 but was not included in the final version. The term goes back to the company
TiVo, which used GPLv2-licensed software in its digital video recorder, but at the same time
technically prevented modified software from being installed and used on the device. In the FSF’s
opinion, this contradicted the principles of the GPL, and after some discussion, the GPLv3 takes
this into account with a paragraph on so-called user products. It generally stipulates that productsthat use GPLv3-licensed software must also provide information on how this software can be
modified.
A further addition concerns patents, which the FSF fundamentally rejects on software withreference to their obstruction of freedom and innovation. This is already stated in the preamble toGPLv3:
Finally, every program is threatened constantly by software patents. States should not allow
patents to restrict development and use of software on general-purpose computers, but inthose that do, we wish to avoid the special danger that patents applied to a free program
could make it effectively proprietary. To prevent this, the GPL assures that patents cannot be
used to render the program non-free.
— GNU General Public License version 3

The license text also contains several passages that allow the inclusion of code under a patent bymeans of a “non-exclusive, worldwide, royalty-free patent license” from the licensor in order toprotect users of such code from disputes between patent holders and licensees.

The GNU Affero General Public License (AGPL)
With the increasing availability and speed of the internet, more and more services are emerging
in which the software is merely installed on the servers of the vendor — the Application Service
Provider (ASP) — and whose customers interact with the services via the internet. The trend has
gained the name Software as a Service (SaaS).
In such cases, the GPLv2 did not provide any clarity as to whether and how the source code
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loophole, known as the ASP loophole, by explicitly referring in section 13 to another license issued
by the FSF in 2007: the GNU Affero General Public License version 3 (GNU AGPLv3). The name goesback to the company Affero, which developed and published the first two versions of this license.
This AGPLv3 basically corresponds to the GPLv3, but explicitly regulates the ASP problem in thesection “remote network interaction.” Furthermore, both licenses explicitly state that they can be
combined with each other without restriction.
In summary, the GNU AGPL is a complementary supplement to the GPL. The AGPL extends thescope of the GPL by applying copyleft to software that is no longer used in local installations, but
exclusively in the form of services transmitted via networks.

Compatibility of Copyleft Licenses
The development of free software thrives on building on the work of others, i.e. integrating,modifying, and sharing the source code of others. If all parts of a modified or newly compiled
software are under the same copyleft license, for example the GPLv3, this is possible without any
legal problems. The license simply requires that the result is distributed under the same license.
Things become more complicated when software consists of parts that are licensed under
different licenses. Several factors need to be taken into account here.

Combined and Derivative Works
Free software is sometimes created under very different conditions. Changes range from simple
error corrections to complex projects with millions of lines of code. Regardless of the scope, abasic distinction is made between two types of works when it comes to licensing: derivative andcombined.
Let’s assume, for example, that software project A is missing a certain functionality. Instead ofdeveloping this functionality from scratch, it makes sense to combine code from another project B,
which offers exactly this functionality, with A. The software from B would not even have to bechanged for this, but could simply be added to A. It is therefore a combined work. If both A and B
are under the same copyleft license, there are no problems for the combined work.
If A and B are under different copyleft licenses, caution is required: Is the combination of A and B
already a separate work? And, if so, under which license can or must it be licensed? Or can aconflict be avoided by ensuring that both parts A and B remain separate with their respective
licenses and do not constitute a new work?
It becomes even more difficult with derivative works, i.e. when project A can make use of B’s

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functionality only by incorporating code from B directly into the code of A. This integration
creates a new, derivative work whose parts can no longer be separated.
Copyleft comes into play for a derivative work. If, for example, A is under a copyleft license suchas the GPLv3, the new, derivative work must also be under the GPLv3 in accordance with theprinciple of reciprocity. But what if B is under a different license? Is it a copyleft license, and is itcompatible with the GPLv3? Or, if it is a different type of license, can B also be published under adifferent license, i.e. relicensed? Or are the licenses of A and B even categorically mutually
exclusive?
The aim in this lesson is not to list the possible combinations and possible solutions. The
important thing is to illustrate the complexity of the problem resulting from the combination ofvery different issues.
Technically, the first thing to clarify is how the different parts of the software (in our example A
and B) work together: Can they be separated from each other or are there processes whose
execution can no longer be clearly assigned to one part or the other?
From a legal point of view, questions arise about the relationship between the licenses of A and B.
Are they compatible with each other, or only in parts or only in one direction? Is relicensing an
option?
We can only hint at the complexity of these questions here, not resolve them. Such decisions callfor sound legal knowledge. Thus, licensing decisions for new works, but especially for combinedand derivative works, should be made early, carefully, and always after detailed legal advice.

Weaker Copyleft
The copyleft has proven to be extremely robust over the past decades, especially in the form of the
GPL in versions 2 and 3. However, special technical requirements have prompted the FSF to reactby adapting its licenses. The GNU Affero General Public License is one such example. We discuss
other examples in the following subsections.

The GNU Lesser General Public License (LGPL)
A method frequently used in software development is the use of small modules for standard tasks,
such as opening or saving files. These modules — or collections of such modules — are referred toas software libraries. They are usually not independently executable applications, but routinesthat the actual application integrates as required. The integration process is known as linking,whereby a distinction is made between two methods.
With static libraries, the actual application (via auxiliary programs and intermediate steps) firmly
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integrates the code of the modules into the executable file of the application. With dynamic
libraries, on the other hand, the application integrates a module only when required at runtime
and loads it into the working memory.
This raises a question with regard to copyleft and licensing: What are the licensing implications oflinking? For example, does this form of taking over code require an application that uses a library
under the GPL to adopt the GPL itself? And does this apply to both static and dynamic linking?
The linking process is so ubiquitous in software development, and the issues associated withreciprocal copyleft so extensive, that the FSF looked early on for a licensing solution that
permitted linking through the GNU Lesser General Public License (LGPL). The LGPL is updated at
the same time as each new version of the GPL. The name of the license in version 1 was the GNU
Library General Public License, which revealed the original problem that led to the license’s
creation. In versions 2 and 3, “Library” replaced by “Lesser” to indicate what is actually at stake,namely a pragmatic weakening of the copyleft principle.
A library licensed under the LGPL can therefore be used by software without this software itself
automatically being subject to the copyleft. Software projects under so-called permissive licenses(covered in another lesson), in particular, benefit from this compromise, as it creates legal
protection for the combination of approaches that are not per se compatible under licensing law.
Any changes to LGPL-licensed software are still subject to the copyleft, i.e. they must also be under
the LGPL.
However, the LGPL-licensed library must be interchangeable, to allow the user of the software to
replace the library with a modified version. Appropriate conditions must be created for this, i.e.
information must be provided on how such a replacement can be made.

Other Copyleft Licenses
Other FOSS projects and organizations also look for the best legal framework for their needs, andhence develop their own licenses. One example is the Mozilla Foundation, founded in 1998 andtoday best known for the two projects it supports: the Firefox internet browser and theThunderbird email client.
Version 1 of the Mozilla Public License (MPL) was published in 1998, and the current (as of 2024)
version 2.0 in 2012.
Like the LGPL, the MPL is often referred to as a “weak copyleft” license. In fact, it seeks to strike abalance between the strict requirements of the copyleft and the possibilities for integration withcommercial products. It achieves this, among other things, through a principle known as file-level
copyleft: If you make a change to a file that belongs to software under the MPL, you can integrate

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this file into proprietary software as long as the modified file itself is remains under the MPL andis therefore accessible.
Another example of a weak copyleft license is the Eclipse Public License (EPL) from the Eclipse
Foundation. The current version 2.0 from 2017 is very similar to the MPL and is often referred toas the most “business-friendly” copyleft license. However, the various copyleft licenses — andthere are others besides the ones mentioned here — often arose due to historical developments
rather than clear legal differences.

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Guided Exercises
1. What does the abbreviation GPL stand for?

2. Why are copyleft licenses also referred to as reciprocal?

3. Which FSF copyleft license is suitable for software libraries?

4. Which English terms replace the term “distribution” in GPLv3 and why?

5. Which of the following copyleft licenses were issued by the Free Software Foundation?
GPL version 3
AGPL version 1
LGPL version 2
MPL 2.0
EPL version 2

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Explorational Exercises
1. Which of the following are copyleft licenses?
GPL version 2
3-clause BSD License
LGPL version 3
CC BY-ND
EPL version 2
2. Can one typically create a derivative work combining parts of two software projects that areunder different strong copyleft licenses? Give reasons!

3. Which of the following licenses have a strong copyleft and which have a weak copyleft?
Common Development and Distribution
License (CDDL) 1.1
GNU AGPLv3
Microsoft Reciprocal License (MS-RL)
IBM Public License (IPL) 1.0
Sleepycat License
4. Describe some compatibility issues that could arise when combining software under a weak
copyleft license with software under a non-copyleft license.

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SummaryThis lesson deals with the characteristics of software licenses that follow the principle of copyleft.
Developed in the 1980s by the Free Software Foundation, the GNU General Public License (GPL) is
currently the most popular license with a strong copyright. Despite several revisions up to thecurrent version 3, its basic requirements have remained virtually unchanged: The freedoms
granted by the license to use, redistribute, and modify the software without restriction must bepreserved at all times. This means that the modified software may be distributed only under thesame conditions (i.e., the same license).
Technical innovations as well as the desire for legal leeway when collaborating with otherprojects have prompted the FSF to develop supplementary or alternative licenses. The GNU Lesser
General Public License (LGPL), for example, takes into account the static or dynamic linking ofsoftware libraries frequently used in software development. The GNU Affero General Public
License (AGPL) responds to the technical trend toward using software in the form of services via
the network (especially the internet), i.e. not in local installations.
In addition to the FSF, other projects such as the Mozilla Foundation and the Eclipse Foundation
have developed copyleft licenses. These also seek a compromise between securing the freedoms
granted by the license and a simpler relationship to software under other licenses by means of a
weaker copyleft.
In principle, license compatibility is an important issue with copyleft licenses, because theprinciple of free, collaborative software development must be reconciled with the legal conditions
determined by the respective license. In any form of combination of software under different
licenses, the legal conditions must be examined carefully in each individual case.

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Answers to Guided Exercises
1. What does the abbreviation GPL stand for?
General Public License
2. Why are copyleft licenses also referred to as reciprocal?
The principle of copyleft requires that freedoms granted by a license must also be granted toothers without restriction. For example, if you make a change to software under the GPL, you
are obliged to make these changes available to others under the same conditions, in accordancewith this reciprocity.
3. Which FSF copyleft license is suitable for software libraries?
GNU Lesser General Public License (GNU LGPL)
4. Which English terms replace the term “distribution” in GPLv3 and why?
The terms “convey” and “propagate” replace “distribution.” The background to this is that theterm “distribution” is firmly anchored in international copyright law. To avoid conflicts or
misunderstandings, the GPL in version 3 does not use this term.
5. Which of the following copyleft licenses were issued by the Free Software Foundation?
GPL version 3

X

AGPL version 1
LGPL version 2

X

MPL 2.0
EPL version 2

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Answers to Explorational Exercises
1. Which of the following are copyleft licenses?
GPL version 2X

3-clause BSD License
LGPL version 3

X

CC BY-ND
EPL version 2

X

2. Can one typically create a derivative work combining parts of two software projects that areunder different strong copyleft licenses? Give reasons!
No. Licenses with a strong copyleft generally require that modified versions are under thesame license. This also excludes relicensing. The combination of licenses, when both follow
these principles, therefore represents an irresolvable contradiction.
3. Which of the following licenses have a strong copyleft and which have a weak copyleft?
Common Development and Distribution
License (CDDL) 1.1

weak

GNU AGPLv3

strongMicrosoft Reciprocal License (MS-RL)

weak

IBM Public License (IPL) 1.0

weak

Sleepycat Licensestrong

4. Describe some compatibility issues that could arise when combining software under a weak
copyleft license with software under a non-copyleft license.
While a strong copyleft requires the modified software to be distributed under the same
license, the conditions are “relaxed” in the case of a weak copyleft. Nevertheless, any
combination with other licenses raises fundamental questions of compatibility. Important
aspects need to be considered when answering these questions: Are the original parts of thetwo software projects clearly separate in the new work and, if necessary, can they still belicensed differently? At what level does the connection between the two original software
projects actually take place? Is source code directly adopted or is it “only” dynamically linked
against the other software (library)? Does one of the two licenses generally allow relicensing?
All questions of this kind can be answered only after a precise analysis of the respective
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licenses and with specialist legal expertise.

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052.3 Permissive Software Licenses
Reference to LPI objectives
Open Source Essentials version 1.0, Exam 050, Objective 052.3
Weight3
Key knowledge areas• Understanding the concept of permissive software licenses• Understanding the rights granted by permissive software licenses• Understanding the obligations created by permissive software licenses• Understanding the main properties of common permissive software licenses• Understanding the compatibility of permissive software licenses with other licenses
Partial list of the used files, terms and utilities• 2-Clause BSD License• 3-Clause BSD License• MIT License• Apache License, version 2.0

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Lesson 1
Certificate:Open Source Essentials

Version:

1.0

Topic:

052 Open Source Software Licenses

Objective:

052.3 Permissive Software Licenses

Lesson:1 of 1Introduction
Permissive licenses are currently the most widely used open-source licenses, in contrast to
restrictive licenses such as the GNU General Public License (GPL). Permissive software licenses
tend to be simple and flexible, and provide a wide range of freedom to their authors — perhaps
the widest freedom available among open source licenses.
This type of license grants broad freedom to software developers regarding the use, modification,and redistribution of the software, so long as they acknowledge the original author. For example,
someone can usually distribute a derivative work under a closed-source license, so long as thework includes attribution for the author of the work from which the new one was derived.
The principle behind this logic is to allow the maximum possible dissemination of the software.
Permissive licenses claim to benefit individuals and the public by facilitating commercial use of
the software, while preserving the rights to the original author through attribution.
It is no coincidence that the first and most important permissive software licenses were developedin the academic field, such as the BSD-like licenses of the University of Berkeley in California or
the MIT/X11 License of the Massachusetts Institute of Technology. These are known as academic

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open source licenses. Their influence within the industry was such that they laid the groundworkfor similar permissive software licenses conceived outside of academic contexts, such as the
Apache License from the Apache Software Foundation.

Rights and Obligations of Permissive Software Licenses
In general, the most popular permissive software licenses grant the licensee the unlimited rightto:
Use the software
Software covered by a permissive software license can be used by anyone (from individual
users, to commercial companies, to public authorities) and for any purpose, whether personalor professional.
Modify the software
The software can be improved, adapted, or even integrated as a component (e.g., a library) into
other software.
Redistribute the software
If the software is modified, taking the form of a derivative work, it can be redistributed under
different licenses, including proprietary ones.
The only obligation in permissive software licenses usually is that of attribution: The licensee isrequired to indicate the name of the original author of the software in the derivative work andinclude a copy of the license text in any redistribution of the software.

Features of the Most Important Permissive Software Licenses
This section explains the differences between the MIT/X11 license, the most common BSD licenses,
and the Apache 2.0 license, all of which are in wide use nowadays.

MIT/X11 License
The MIT/X11 license (text: https://opensource.org/license/mit), also known as the X11 license, is
one of the academic licenses mentioned earlier. The license takes its name from the X Window
System software developed by the Massachusetts Institute of Technology back in 1987. This license
is one of the oldest and most popular permissive software licenses, partly because of its simple,
clear language.
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The sole obligation of the licensee is to include the copyright notice and the license text in thesource code of the software or of its derivative works.
The MIT/X11 license is considered to be compatible with all the most important copyleft licenses,
both weak and strong. In particular, the MIT/X11 license is compatible with the• GNU General Public License (GPL), versions 2.0 and 3.0• GNU Lesser General Public License (LGPL), versions 2.0 and 3.0• Mozilla Public License (MPL)
That means that derivative works of software originally licensed under the MIT/X11 license can beredistributed under one of the above-mentioned licenses or be included in projects released
under one of the above-mentioned licenses.

2-Clause BSD License
The 2-Clause BSD License (text: https://opensource.org/license/bsd-2-clause) derives from theoriginal BSD license, created in 1980 by the University of Berkeley in California as the license for
BSD, its Unix-like operating system.
The license is well known for its simplicity and, as its name indicates, consists of just two shortclauses. It is substantially identical to the MIT/X11 license. Like the MIT/X11 license, this one
requires attribution in the software. Additionally, the 2-Clause BSD License requires the licensee
to include the license text in the documentation and other materials provided when redistributing
the code.
To summarize, the 2-Clause BSD license grants the rights to:• Use, modify, and distribute the software• Commercialize the software, with or without modification• Release derivative works under a different license, even as closed-source software
The licensee has the obligation to:• Include the copyright notice and the license text in the source code and binary of the software
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Open Source Essentials (Version 1.0) | Topic 052: Open Source Software Licenses• Include the copyright notice and the license text in documentation or other materials provided
with the software
The 2-Clause BSD license is considered to be compatible with all major copyleft licenses, both
weak and strong. In particular, the 2-Clause BSD license is compatible with:• GNU General Public License (GPL), versions 2.0 and 3.0• GNU Lesser General Public License (LGPL), versions 2.0 and 3.0• Mozilla Public License (MPL)
Therefore, derivative works of software originally licensed under the 2-Clause BSD license can beredistributed under one of the above-mentioned licenses or be included in projects released
under one of the above-mentioned licenses.

3-Clause BSD License
The 3-Clause BSD license (text: https://opensource.org/license/bsd-3-clause) is yet another variantof the original BSD license, consisting of just three clauses. The main feature distinguishing thislicense from the sister 2-Clause BSD license is the “non-endorsement clause,” which aims toprevent the name of the original author from being exploited to distribute or sell derivative
works.
The 3-Clause BSD license grants the licensee the rights to:• Use, modify, and distribute the software• Commercialize the software, with or without modifications• Release derivative works under a different license, even as closed-source software
The licensee has the obligation to:• Include the copyright notice and the license text in the source code and binary of the software
or of its derivative works• Include the copyright notice and the license text in documentation or other materials provided
with the software• Refrain from citing the name of the copyright holder or contributors to endorse or promote
products derived from this software, without specific prior written permission
In order to explain the latter obligation — the “non-endorsement clause” — let’s think of a
scenario in which a company or individual creates a derivative work starting from software
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promote the new work by indicating that it is a derivative of software by a well-known developer,
in order to benefit from their prestige.
As with its sister license, the 3-Clause BSD license is considered to be compatible with all the mostimportant copyleft licenses, both weak and strong. In particular, the 3-Clause BSD license iscompatible with:• GNU General Public License (GPL), version 2.0 and 3.0• GNU Lesser General Public License (LGPL), version 2 and 3• Mozilla Public License (MPL)
Therefore, derivative works of software originally licensed under the 3-Clause BSD license can beredistributed under one of the above-mentioned licenses or be included in projects released
under one of the above-mentioned licenses.

Apache 2.0 License
The first Apache license was developed by the Apache Software Foundation, a nonprofit
organization established in 1999, to distribute its software and make it easy to include in otherprojects. The mission was to guarantee collaborative software development, embracing the opensource philosophy with a business-friendly perspective.
The Apache 2.0 license (text: https://www.apache.org/licenses/LICENSE-2.0), probably the mostwidespread among the permissive software licenses, differs from the licenses discussed
previously in a few relevant aspects. The main aspect concerns the attribution of patent rights toeach licensee, including a clause related to the termination of the patent license, so as to limit andprevent any claims for damages for patent infringement.
Two other obligations are significant. The licensee must release, under the same Apache 2.0
license, any parts or components of the software not modified by the licensee. Furthermore, thelicensee must place prominent notices in any modified files stating that the licensee changed thosefiles.
The Free Software Foundation, which promotes restrictive licenses, recommends Apache 2.0 as
the best of the permissive software licenses for distributing small amounts of software andlibraries.
The Apache 2.0 license grants the licensee:• The right to use, modify and distribute the software• the right to commercialize the software, with or without modifications

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Open Source Essentials (Version 1.0) | Topic 052: Open Source Software Licenses• The right to release derivative works under a different license, even as closed-source software• A patent license to use, sell, import, and otherwise transfer the software covered by a patent• A patent license to use, sell, import, and otherwise transfer the software which might otherwise
infringe a contributor’s patent claim
The licensee has the obligation to:• Place prominent notices in any modified files stating that the files have been modified• Release all unmodified parts of the original software under the Apache 2.0 license• Include the copyright notice and the license text in the source code of the software and its
derivative works• Include the copyright notice and the license text in documentation and other materials
provided with the software
The Apache 2.0 license is considered to be compatible with only some of the most important
copyleft licenses. In particular, the Apache 2.0 license is compatible with:• GNU General Public License (GPL), version 3.0 but not 2.0• GNU Lesser General Public License (LGPL), version 3.0 but not 2.0• Mozilla Public License (MPL), version 2.0 but not version 1.1
That means that derivative works of software originally licensed under the Apache 2.0 license canbe redistributed under one of the above-mentioned compatible licenses or be included in projects
released under one of the above-mentioned compatible licenses.
The limited compatibility between the Apache 2.0 license and other open source licenses is
primarily due to the presence of clauses related to the grant of a patent license to the licensee.

Permissive Software Licenses in Relation to Other Open Source
Licenses
Now that we have an overview of the common and essential features of permissive software
licenses, we can move on to examine how they differ from the public domain software and from
copyleft licenses.

Comparison to Public Domain Software
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software. In other words, by definition, works in the public domain have no license.
The next distinction lies in the obligations that permissive licenses impose on the licensee. In fact,
the user of a public domain release has no obligations whatsoever. However, anyone who uses,
modifies, or redistributes software under a permissive software license must comply with theattribution obligation explained earlier: a requirement to include the name of the original author
and a copy of the license text in the software.
The consequence of the attribution obligation is that no derivative work originating from software
under a permissive software license can be released as public domain, because this would violate(or at least circumvent) the original author’s right to receive attribution.

Comparison to Copyleft
The distinction between permissive software licenses and restrictive, copyleft licenses is more
complex, especially considering the differences between various copyleft licenses. As seen inprevious lessons, one major difference separates strong copyleft licenses (including GNU General
Public License (GPL), version 2.0 and 3.0) from weak copyleft licenses (including GNU Lesser
General Public License (LGPL), version 2.0 and 3.0, and the Mozilla Public License).
The major difference between restrictive licenses and permissive licenses lies in the copyleft
principle, which is core to restrictive licenses. In conformance with this principle, the licensee
who modifies software under copyleft license, and then distributes it, must necessarily
release — totally or partially — the derivative work with the same license as the original software.
Failure to comply with this obligation results in copyright infringement, with its attendant legal
consequences.
On the contrary, permissive software licenses do not impose such an obligation. Those who use orplan to release software under this type of licenses can freely decide the license for theirderivative work, including proprietary licenses.
Strong Copyleft
The difference between permissive software licenses and strong copyleft licenses are moremarked than with weak copyleft licenses.
The essential difference is that strong copyleft licenses require derivative works to be released
under the same license as the original software. This also applies if the copyleft-licensed softwareis integrated into another project: The entire derivative work must be released under the samestrong copyleft license.

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Weak Copyleft
Unlike strong copyleft licenses, weak ones have only a partial requirement to release a derivative
work under the same license. To be more specific, the licensee who redistributes software
released under a weak copyleft license must apply the same license to the portion of their work
derived from the original one. For example, a library based on a library licensed under the LGPL
must also be licensed under the LGPL.
The weak copyleft licenses were conceived precisely to bring their features closer to those of thepermissive software licenses. They are nevertheless distinguished from permissive software
licenses in that the latter do not impose, under any circumstances, an obligation to maintain thesame license on a derivative or integrated work.

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Guided Exercises
1. What are the two obligations generally imposed by permissive software licenses?

2. Which of the following licenses is not a permissive software license?
Apache 2.0 license
LGPL license
MIT/X11 license
3-Clause BSD
3. What distinguishes a permissive software license from a copyleft license?
Software released under a copyleft license
cannot be distributed, whereas softare under
permissive software license can.
The works derived from software under acopyleft license cannot be released under aproprietary license, whereas software under apermissive software license can.
Copyleft licenses are legally recognized only in
the United States of America, whereas
permissive software licenses are globally
recognized.
4. Which permissive software license grants a patent license to use, sell, import, and otherwisetransfer the software covered by a patent?
Apache 2.0 license
2-Clause BSD license
MIT/X11 license
3-Clause BSD license
5. When software is released under the MIT/X11 license, can you distribute it under a proprietary
license and sell a derivative work based on the software?

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Explorational Exercises
1. You are modifying software distributed under the Apache 2.0 license and redistributing thederivative work under a proprietary license. What steps should you follow to be compliant
with the Apache 2.0 license obligations?

2. Name at least three examples of popular projects released under permissive software licenses.

3. Why can’t you distribute, under a LGPL 2.0 license, software that includes components thatwere originally released under the MIT/X11 license, the Apache 2.0 license, and the 2-Clause
BSD license? What different weak copyleft license can be used to release the software?

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Summary
In this lesson you have learned: * What permissive software licenses are, the rights they grant,
and the obligations they provide * The differences between permissive software licenses andother open source licenses * Features of the most popular permissive software licenses *Compatibility of permissive software licenses with other open-source licenses

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Answers to Guided Exercises
1. What are the two obligations generally imposed by permissive software licenses?
The obligation to indicate the name of the original author of the software and to include a copyof the text of the license in the derived work.
2. Which of the following licenses is not a permissive software license?
Apache 2.0 license
LGPL license

X

MIT/X11 license
3-Clause BSD
3. What distinguishes a permissive software license from a copyleft license?
Software released under a copyleft license
cannot be distributed, whereas softare under
permissive software license can.
The works derived from software under aXcopyleft license cannot be released under aproprietary license, whereas software under apermissive software license can.
Copyleft licenses are legally recognized only in
the United States of America, whereas
permissive software licenses are globally
recognized.
4. Which permissive software license grants a patent license to use, sell, import, and otherwisetransfer the software covered by a patent?
Apache 2.0 licenseX

2-Clause BSD license
MIT/X11 license
3-Clause BSD license
5. When software is released under the MIT/X11 license, can you distribute it under a proprietary
license and sell a derivative work based on the software?
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Yes.

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Answers to Explorational Exercises
1. You are modifying software distributed under the Apache 2.0 license and redistributing thederivative work under a proprietary license. What steps should you follow to be compliant
with the Apache 2.0 license obligations?
You should:◦ Insert into each modified file a notice attesting that the files have been modified.
◦ Release all unmodified parts of the original software under the Apache 2.0 license.
◦ Include the copyright notice and the license text in the source code of the software or of its
derivative works.
◦ Include the copyright notice and the license text in documentation and other materials
provided with the distribution of the software.
2. Name at least three examples of popular projects released under permissive software licenses.
◦ Angular web framework — MIT/X11 license◦ Ruby on Rails — MIT/X11 license◦ Apache HTTP Server — Apache 2.0 license◦ Kubernetes — Apache 2.0 license
3. Why can’t you distribute, under a LGPL 2.0 license, software that includes components thatwere originally released under the MIT/X11 license, the Apache 2.0 license, and the 2-Clause
BSD license? What different weak copyleft license can be used to release the software?
Even though the MIT/X11 license and 2-Clause BSD license are compatible with the LGPL 2.0
license, the Apache 2.0 license is not. Software that includes components released under
MIT/X11 license, Apache 2.0 license, and 2-Clause BSD license can be released under LGPL 3.0
license, because it is compatible with all those permissive software licenses.

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053.1 Concepts of Open Content Licenses
Reference to LPI objectives
Open Source Essentials version 1.0, Exam 050, Objective 053.1
Weight2
Key knowledge areas• Understanding types of open content• Understanding what constitutes content that is subject to copyright• Understanding derivative works of copyrighted materials• Understanding the need for open content licenses• Awareness of trademarks
Partial list of the used files, terms and utilities• Documentation• Images• Artwork• Maps• Music• Videos• Hardware designs and specifications• Databases• Data streams

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Lesson 1
Certificate:Open Source Essentials

Version:

1.0

Topic:

053 Open Content Licenses

Objective:

053.1 Concepts of Open Content Licenses

Lesson:1 of 1Introduction
Think about this hypothetical situation: Frank is a writer who wants to make some of his stories
available to anyone on the internet, but under certain conditions. He wants his work to be free ofcost. He wants anyone to be able to use the stories without asking for permission, but he doesn’twant his work to be used commercially. Finally, he wants people to credit him properly if thestories are used for any purpose. He would like to do this without involving himself incomplicated legal processes. We’ll see later why a writer might want to do these things.
Emma is a filmmaker who teaches some students how to produce short films. Among other things,
the students need a story to create their works. Emma knows Frank’s stories and thinks they are
perfect for her class.
What can Frank do to allow Emma to use his stories? This situation and many more can be solved
by using an open content licensing model. Nowadays, millions of copyright-protected works can bereused by anybody without explicit consent from the copyright holder or the payment of a licensefee, thanks to their distribution under open content licenses. Resources such as Wikipedia, Flickr,
OpenStreetMap, Unsplash, and Jamendo are some examples of the many platforms that use thislicense model.

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According to a very broad definition, open content refers to any work (including, for example,
movies, music, images, texts, databases, data sets, documentation, maps, and hardware designs)
whose free use and redistribution is permitted under copyright law. This also includes originallyprotected works whose term of protection has expired and which are therefore in the publicdomain. A somewhat narrower definition presupposes that a work has been explicitly placed
under an open content license by its author, which allows use and distribution of the workwithout any payment or permission. The open content model is therefore not in opposition tocopyright law, but complements it.

Copyright Fundamentals
Because open content licenses are based on copyright, you need to learn some aspects of copyright
law in order to understand why the licenses are needed and what they allow.
Copyright is a part of a legal category known as intellectual property. Copyright protects original
works by granting its creators exclusive legal rights to control certain uses of their works by otherpeople and corporations. Generally, this means that no one else can copy, distribute, publicly
perform, adapt, or do almost anything else other than view or read the work without thepermission of the copyright holder.
The fundamentals we will examine in this section include what is copyrightable, along with who
controls the rights and can grant permission to reuse a copyrighted work as Emma wants to do in
our example.
As explicitly stated by the World Intellectual Property Organization:
Copyright protects two types of rights. Economic rights allow right owners to derive financial
reward from the use of their works by others. Moral rights allow authors and creators to takecertain actions to preserve and protect their link with their work. The author or creator may
be the owner of the economic rights or those rights may be transferred to one or more
copyright owners. Many countries do not allow the transfer of moral rights. Copyright only
protects the expression of facts or ideas. It does not allow the copyright holder to own orcontrol the idea exclusively. For example, an illustration can be copyrighted but not the ideathat originated it.
— World Intellectual Property Organisation, Understanding Copyright and Related Rights

Economic rights protected by copyright last a long time, generally decades after the creator dies.
Moral rights never expire.
Copyright grants rights to creative works, such as literary and artistic creations that must meet acertain standard of originality. The work must be a creation of its creator and not copied from

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another work. (There are ongoing debates about how much artificial intelligence can go into awork and still have it be considered original.)
Copyright protects only the expression of facts or ideas. It does not allow the copyright holder toown or control the idea exclusively. For example, an illustration can be copyrighted, but not theidea that originated it.
Copyright is automatic when a work is created and fixed in some tangible form, for example, adigital artwork or a song. This means that the rights are granted to the creator without evenformally registering the work.
The people who promote open content licensing want to promote a free culture and thedevelopment of a digital commons. They have found the copyright system too restrictive and rigid
for both users and creators. By creating easy-to-use standard licenses, the open content advocatessimplify the use and distribution of works protected by copyright.

What Can Be Copyrighted?
Copyright laws vary from country to country. However, there are international agreements tostandardize copyright laws. Original literary and artistic works can be copyrighted: for example,
works in art, music, photography, film, television, literature, and programming. The particular
rules to decide what is copyrightable, and how original a work is, vary depending on the region.
Sometimes these categories can be very general and apply to works that have both creative andstrictly functional elements: For example, a short film is considered artistic work. However,portions of it can be uncopyrightable if they do not meet the standard of originality.

Derivative Works
Let’s continue with the hypothetical situation from the beginning of the lesson: Frank ultimately
decided to publish his stories under an open content license so they can be used under the terms
he chose. Since the stories came under that license, Emma used them in her class and decided toshow some of her students' short films during a film festival. In this case, the content created by
the students can be considered derivative works.
A derivative work or adaptation is a work based on existing works, such as a translation, musicalarrangement, dramatization, fictionalization, motion picture version, sound recording, art
reproduction, or any other form in which the original work is transformed or adapted. The
derivative work becomes a second, separate work independent in form from the first. The
transformation, modification, or adaptation of the work must be substantial in order to beoriginal and thus protected by copyright.

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Common Open Content Licenses Features
Every open content license asserts the copyright of the author and affirms that without a licensefrom the author, any person using the work would be in violation of copyright. Therefore, suchlicenses work within the global copyright system instead of trying to overturn it.
Open content licenses also ensure that appropriate credits should be given to the author of thework. If recipients of the work distribute it to a third party, they should ensure that the original
author is acknowledged and credited. Also, when recipients modify the work, the derivative work
should clearly mention the author of the original and mention where the original can be found.
Unlike most copyright licenses, which impose restrictive conditions on uses of the work, open
content licenses enable users to have certain freedoms by granting them rights. Some of theserights are common to virtually all open content licenses, such as the right to copy the work andthe right to distribute the work. Depending on the license, the user may also have the right tomodify the work, create derivative works, perform the work, display the work, and distribute thederivative works.
Open content licenses can control derivative works. These licenses normally include the right tocreate a derivative work and distribute it in any media. If a person licenses a painting under anopen content license, the right to base another picture on it can be granted as well. Thesepermissions are granted on the condition that others may use the derivative work freely, just likethe original work.
Therefore, an open content license normally ensures that derivative works are licensed under theterms and conditions of the same open content license. But this obligation is not applicable when
the work is included in a compilation. For example, if a person makes an album of songs, one ofwhich is licensed under an open content license, not all the songs have to be licensed under thesame terms.
Another important aspect of open content licenses is the control of commercial use of a work.
People can license their works under an open content license while restricting the rights tononcommercial purposes. Alternatively, people may also grant all rights, including the right to use
the work commercially.
Open content licenses don’t stop people from making money from their work. If a work is under anoncommercial license, a publisher or other commercial entity may publish the work by making
an agreement with the copyright holders before doing so. In other words, even after releasing apiece of work on a noncommercial basis, authors may sell the copyright to a for-profit entity,
provided that there is no exclusion placed upon continuing, noncommercial usage.

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Importance of Open Content Licenses
What are some of the benefits of an open content model, and why would people use an open
content license to distribute their creative work rather than relying on the traditional copyrightmodel?
Open content licenses allow works to circulate more widely than if they were restricted bydefault. Therefore, new artists could benefit from these licenses, as they can become more
popular and recognized by more people. By relinquishing certain controls (and possibly therevenues that go along with them) content creators can be invited to more shows, obtain moresponsorships, make more collaborations, etc.
Open content licenses can be practical in the internet age, because creators can publish theirworks without relying on another person or institution. For example, a photographer who wants
to exhibit their photos could publish them on a personal website. This way, they can establish
themselves and be known to a wider public without signing up an agency or gallery to do so.
By choosing the right license, rights holders can maximize distribution and maintain control of
the commercialization of their works. If people want to use a work commercially, the content
creator can preserve the right to grant or withhold permission. Even if others are prohibited fromcommercial use, rights holders may still use their work commercially.
Besides the possibility of a much broader distribution of a work, open content licenses also
increase legal certainty for users and significantly decrease legal transaction costs.
People may also use funding models that do not depend on using a noncommercial license. For
example, many artists and creators use crowdfunding to fund their work before releasing it undera permissive license. Others use a model where the basic content is free, but extras such as
printed versions or special access to a members-only website are for paying customers only.
Open content licenses allow people to distribute their works to anybody and on any media andformat such as websites, photocopies, CDs, or books, without restrictions.
Open content licenses automatically establish a license between authors and users. Without an
open content license, the sharing of works via another online source would require an individual
contractual agreement between authors and users.

Trademarks and Copyrights
Trademarks, like copyright, are a type of intellectual property. But the law that protects a
trademark is different from that protecting copyright. Trademarks protect brands, related words
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particular goods and services from others. Any special element used to promote and distinguishbusinesses and the services or products sold from others can be a trademark.
The holder of a trademark is generally allowed to prevent others from using these trademarked
items if the public will be confused. Trademark law helps producers of goods and services protect
their reputation, and protects the public by giving them a simple way to differentiate between
similar products and services.
Trademarks can be registered officially or be automatically protected under common law. Thismeans that a trademark exists as soon as it is being used, but a common-law trademark does notoffer the same legal protection as a registered trademark. That’s why many companies register
their trademarks.
Copyright and trademarks can coexist. For example, Wikipedia is a registered trademark, and its
logo is also protected under copyright law as an original artwork or creation.

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Guided Exercises
1. Can open content licenses be used to avoid copyright?

2. What is considered open content?

3. What is a derivative work?

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Explorational Exercises
1. What would you do if you want to publish a work and allow people to use it for any purposesas long as they redistribute the work under the same rights and conditions?

2. Can you distribute commercial derivative works based on works published under an open
content license?

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Summary
In this lesson, you learned:• Fundamentals of copyright law• What can be considered copyrightable content• What a derivate work or adaptation is• Common features shared by open content licenses• Types of open content• Importance and benefits of the open content licensing model• Copyright and trademarks as intellectual property types

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Answers to Guided Exercises
1. Can open content licenses be used to avoid copyright?
Open content licenses cannot be used to avoid copyright. Open content licenses are a type of
copyright license that grant some rights under certain conditions, while maintaining theexclusive rights of the copyright holder.
2. What is considered open content?
Open content can be any copyrightable work published under an open content license. This
content can be movies, music, images, texts, databases, documentation, maps, and hardware
designs, and other creations. These types of licenses grant rights such as use, redistribution,
making derivative works, and commercial or noncommercial use without any special
permission.
3. What is a derivative work?
A derivative work, also called an adaptation, is a work based on an existing work in which theoriginal work is transformed or adapted. Translations, musical arrangements, dramatizations,motion picture versions, sound recordings, and art reproductions are examples of derivative
works.

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Answers to Explorational Exercises
1. What would you do if you want to publish a work and allow people to use it for any purposesas long as they redistribute the work under the same rights and conditions?
You can make the work available under a copyleft-type license. This way, all derivate works ofthe original must be open as well, requiring them to be published under the same or any othercompatible license.
2. Can you distribute commercial derivative works based on works published under an open
content license?
It depends on the license under which the original work is available. If the license states thatyou can use derivative works for any purpose, even commercially, then you can.

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053.2 Creative Commons Licenses
Reference to LPI objectives
Open Source Essentials version 1.0, Exam 050, Objective 053.2
Weight2
Key knowledge areas• Understanding the concept of Creative Commons licenses• Understand the Creative Commons license types and their combinations• Understanding the rights granted by Creative Commons licenses• Understanding the obligations created by Creative Commons licenses
Partial list of the used files, terms and utilities• Public Domain Dedication (CC0)• Creative Commons Attribution (CC BY)• Creative Commons Attribution-ShareAlike (CC BY-SA)• Creative Commons Attribution-NonCommercial (CC BY-NC)• Creative Commons Attribution-NonCommercial-ShareAlike (CC BY-NC-SA)• Creative Commons Attribution-NoDerivatives (CC BY-ND)• Creative Commons Attribution-NonCommercial-NoDerivatives (CC BY-NC-ND)

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Lesson 1
Certificate:Open Source Essentials

Version:

1.0

Topic:

053 Open Content Licenses

Objective:

053.2 Creative Commons Licenses

Lesson:1 of 1Introduction
The success of free software since the 1990s, along with the simultaneous triumph of the internet,
have awakened a desire in other sectors for similar conditions to support the development anddistribution of creative works, i.e. works that are fundamentally subject to copyright. Thesedesires reflect a variety of interests.
Creative artists want to determine for themselves the conditions under which their works can beused by others. At the same time, however, they also have an interest in using the work of others
for themselves, as creative processes have always done, for example by quoting, editing, or
adapting. For the recipients of the works, questions arise as to the possibilities for use, forexample whether and in what form a work may be reproduced or passed on.
In addition to clarifying such practical questions, regulations must be made in such a way thatthey are in line with applicable legal norms — primarily copyright law — which is made moredifficult by the diverse ways copyright law is regulated internationally.
Last but not least, the rules should be easy to understand and simple to apply, in order to speed up
creative processes and give creators and recipients legal certainty.

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Origin and Goals of Creative Commons
The early licenses in the area of free software, above all the GNU General Public License, had done
pioneering work, as they had succeeded in providing a reliable legal framework for thecompletely new processes surrounding the collaborative development of software.
In 2001, a group led by law professor Lawrence Lessig from Stanford Law School founded a nonprofit organization called Creative Commons (CC), inspired by free software. The organization’s
goal is summarized on the project website as follows:
Creative Commons is a global nonprofit organization that enables sharing and reuse ofcreativity and knowledge through the provision of free legal tools.
— Creative Commons, Website (FAQ)

With the term “commons,” referring to a form of communal economic activity already
documented in the Middle Ages, the organization emphasizes a historically verifiable, deeply
human need for collective action that is oriented toward the common good. Their self-imposed
task is therefore to create a modern legal framework for creative work. Creative Commonstransfers the demands and solutions of the free software movement to other creative fields suchas literature, the performing arts (painting, graphics, photography, video, etc.), and music, but also
documentation and scientific work — roughly speaking, all works that are subject to copyright.
Similar to the Free Software Foundation, Creative Commons also chooses to implement its goals
through licenses: compilations of standardized, legally binding specifications that creators
explicitly assign to their works, usually before they “release” works to the public, i.e. publish
them.
The “all rights reserved” principle enshrined in US copyright law is perceived as too restrictive inview of the constantly growing technical possibilities available to creative processes. Creatorsthemselves are often unclear as to how far they are allowed to build on the work of others
without exceeding the limits of copyright law and, in the worst case, making themselves liable toprosecution. Creative Commons contrasts this heavy-handed regime with the principle of “somerights reserved”: The creators name those rights that they reserve — and thus waive all others.
The combination of just four simple basic conditions (modules) results in a total of six licenses
from which authors can select and assign the appropriate one for their work.

The Creative Commons License Modules
The four modules just mentioned correspond to four simple basic decisions that an author makeswith regard to the use and distribution of a work. Each module can be represented by two-letter

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abbreviation and a symbol. The respective definition is very short and understandable even forlegal laypersons, which contributes greatly to the popularity of CC licenses. In individual cases,
however, the clauses can lead to unresolved questions or gray areas.

Attribution (BY)
You must give appropriate credit, provide a link to the license, and indicate if changes were
made. You may do so in any reasonable manner, but not in any way that suggests thelicensor endorses you or your use.
— Creative Commons, Attribution

The English word “by” indicates that the authors must be named, i.e. the work must be clearly
attributed to the authors if it is used, reproduced, or passed on in any form. The BY module is the
only one that is mandatory in all CC licenses. In other words, there is no work under the six
standard CC licenses that can escape attribution.
This simple requirement can cause practical problems in collaborative projects developed overthe internet. For example, in works derived from the online encyclopedia Wikipedia, it is quite
questionable how “attribution” is to be “appropriately” carried out with thousands ofcontributors.

NonCommercial (NC)You may not use the material for commercial purposes.
— Creative Commons, NonCommercial

The intention of the NonCommercial module seems clear at first glance: It is intended to prevent a
freely available work from being appropriated by others for commercial purposes. This often
concerns works that have been developed with public funds, for example at universities. These
are meant to be “protected” from commercialization in order to ensure their quality and longterm free availability.
In fact, the NC module often causes uncertainty in practice, as it is by no means clear in individual
cases when a use is actually commercial. Teachers who use materials under a CC license with an
NC module, for example, are already in a legal grey area if they teach at a private school or a
private university that students have to pay to attend.
Many critics of the NC module also reject the argument that free materials become “non-free”
through commercial use, because the works are still also available free of charge.

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NoDerivs (ND)
If you remix, transform, or build upon the material, you may not distribute the modified
material.
— Creative Commons, NoDerivs

Derivatives (short: Derivs), meaning derivative works, have already been mentioned in otherlessons. In the context of Creative Commons, the term also refers to the creation of new works on
the basis of existing works covered by copyright; these can be learning materials that a teacher
adapts for his lessons, for example, or the translation of a novel into another language. NoDerivs
categorically excludes the distribution of modifications or adaptations of this kind: The work may
be passed on only in the form published by the author.

Share Alike (SA)If you remix, transform, or build upon the material, you must distribute your contributions
under the same license as the original.
— Creative Commons, ShareAlikeThe ShareAlike module indicates that a work may be shared only under the same conditions as
those of the assigned license. SA is regarded as the counterpart to the copyleft principle in the free
software licenses, which ensures that the freedoms granted by the license also apply unchanged toderived works.
The SA module is particularly interesting in combination with other modules because the SA
requirement also updates other defined conditions, as we will see as we discuss the various
licenses.

The Creative Commons Core Licenses
The combinations of the modules just presented result in a total of six licenses. There are only six
because not all possible combinations of the four modules make sense: For example, therequirements to share even modified works under the same conditions (ShareAlike) and theprohibition of adaptations (NoDerivs) are mutually exclusive. Consequently, there is no licensethat contains both modules. Since the attribution of the author is also a component of all licenses,
the result is the so-called core licenses we’ll discuss next.
The list of these licenses can also be imagined as a scale from “many freedoms” to “few freedoms,”
since an author answers questions about the possibilities of use or their restrictions in relation to
the work step by step and thus finally receives the desired license.

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Creative Commons Attribution (CC BY)
The attribution of the author has already been mentioned as a mandatory component of all
licenses, and so the first license, CC Attribution, includes only this module. A work is thus released
for any form of use, modification, and distribution as long as the attribution requirement is met.

Figure 5. CC BY Icon

For example, if an author has published a poem under CC BY, a publisher could include it in acollection of poems without consulting the author and without any financial obligations anddistribute it through bookstores, for example, as long as this poem is clearly marked as theauthor’s work.

Creative Commons Attribution-ShareAlike (CC BY-SA)
CC Attribution-ShareAlike_ corresponds to CC BY, but supplements it with the requirements ofShareAlike, i.e. the distribution of modified versions of the work under the same conditions.

Figure 6. CC BY-SA Icon

For example, if a singer places her song under the CC BY-SA license, another band can cover or
adapt this work, provided that they in turn publish their version of the song under under CC BYSA or another license that is compatible with it.

Creative Commons Attribution-NonCommercial (CC BY-NC)
The CC Attribution-NonCommercial is the first license in the series that links the use of a work to aprohibition by excluding distribution and adaptation for commercial purposes.

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Figure 7. CC BY-NC Icon

In our example, a band would be allowed to adapt the singer’s song, but not to use this adaptationcommercially, for example not to sell it on their own records or play it at concerts for which theyreceive a fee. However, the band would be allowed to additionally prohibit adaptations of theirversion, i.e. to publish the adaptation under the CC BY-NC-ND license.

Creative Commnons Attribution-NonCommercial-ShareAlike (CC BY-NC-SA)
In the case of CC Attribution-NonCommercial-ShareAlike, the prohibition of commercial use islinked to distribution under the same conditions. To stay with our example: Although the band isallowed to cover the singer’s song, it is not allowed to add ND to the cover version because thearrangement must be distributed under the same conditions.

Figure 8. CC BY-NC-SA Icon

Creative Commons Attribution-NoDerivs (CC BY-ND)
Like NonCommercial, CC Attribution-NoDerivs is also based on a prohibition — in this case, theprohibition to modify or adapt a work. The band in our example would therefore not be allowed
to distribute a cover version of the singer’s song.

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Figure 9. CC BY-ND Icon

The use of CC licenses with ND clauses (i.e. CC BY-ND license and the CC BY-NC-ND licensepresented next) is viewed with scepticism, particularly in the scientific field, because they canhinder the exchange of knowledge necessary for scientific progress. Even on the Creative
Commons website, licenses with an ND module are described as incompatible with the principleof open access that is popular in science. As an example of the overly restrictive tendency of ND, it
is cited that even translations of scientific articles are regarded as derivative works and are
therefore prohibited.

Creative Commons Attribution-NonCommercial-NoDerivs (CC BY-NC-ND)
The most restrictive of the CC licenses, CC Attribution-NonCommercial-NoDerivs, combines theprohibition of commercial use with that of the distribution of derived works. In positive terms,
this means that a work may be reproduced and distributed only in the form published by theauthor and may be used only for non-commercial purposes.

Figure 10. CC_BY-NC-ND_Icon

The singer in our example thus prevents a band from covering her song (ND), but at the same timerisks her song being excluded from on any platform that generates revenue from customers or
advertising.

Creative Commons Zero (CC0) and the Public Domain MarkIt has already been mentioned that copyright law is regulated very differently in different
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copyright. By doing so, they transfer their work to the so-called public domain, i.e. to general andunrestricted use.
In most European countries, however, in addition to the pure rights of use, copyright also includes
personal rights, which are generally not transferable and therefore cannot be waived by theauthor. If an author wishes to release a work to the public, they waive all rights of use, but remain
the author.
In addition, there are works whose use is not subject to any restrictions per se. These include, forexample, works whose legal term of protection has expired (such as a novel 70 years after theauthor’s death), or works that were never protected in principle (such as legal texts).
Creative Commons provides two so-called public domain tools to identify works that are available
to the general public without restriction.
Creative Commons Zero (CC0) attaches virtually zero conditions to the reproduction, distribution,and modification of a work. The obligatory attribution of the author in all CC licenses is also
omitted. The license allows rights holders to mark their works as public domain in as many legal
systems as possible.

Figure 11. CC0 Icon

Let’s take a learning document developed for teaching purposes as an example. The author or
authors can use the CC0 label to ensure that this material can be used by anyone without any
restrictions: It can be copied in whole or in part, distributed free of charge or for a fee, andintegrated in whole or in part into other documents. The original authors do not have to be named
anywhere.
To identify works that are not subject to copyright restrictions, Creative Commons recommends
the Public Domain Mark:The Public Domain Mark operates as a tag or a label, allowing institutions like those as wellas others with such knowledge to communicate that a work is no longer restricted bycopyright and can be freely used by others.
— Creative Commons, Public Domain Mark

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Figure 12. Public Domain Mark Icon

Selecting Licenses and Marking Works
It has already been mentioned that Creative Commons aims to be as simple as possible for bothlicensors (content creators) and licensees (recipients of the works). In concrete terms, theorganization offers a great deal of assistance from the selection of the appropriate license to thelabeling of the work and its use.
The CC License Chooser on the organization’s website leads step by step to the recommendation of
the appropriate license by posing simple questions that an author answers in relation to thedesired use of their work (CC License Chooser).

Figure 13. CC License Chooser

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If the proposed license corresponds to the author’s intentions, they can mark their work
accordingly. The License Chooser provides HTML code, for example, which the author can add
directly to a website displaying the work (HTML code with link to the license).

Figure 14. HTML code with link to the license

The result is then a standardized notice with the link to the corresponding license (License noticewith link to the license).

Figure 15. License notice with link to the license

The license-specific icons, in which the included modules are directly visible, have already been
introduced. They have established themselves as “eye-catchers” identifying free content on theinternet.

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International and Ported Licenses
From the outset, Creative Commons has focused on the development of licenses that are as
general as possible, i.e. valid worldwide, which it identifies accordingly with the addition of“international” (formerly also “unported”). On the other hand, there are variants that take into
account the peculiarities of a regional or national legal system and are referred to as “ported.” Forexample, in addition to the CC BY-SA 3.0 Unported license, there is also a special version forGermany under the name CC BY-SA 3.0 Germany.
With the currently valid version 4.0 of the CC licenses, Creative Commons is striving for further
standardization and has (so far) completely dispensed with ported versions. In version 4.0, the“international” license: is expressly recommended:
We recommend that you use a version 4.0 international license. This is the most up-to-dateversion of our licenses, drafted after broad consultation with our global network of affiliates,
and it has been written to be internationally valid. There are currently no ports of 4.0, and it
is planned that few, if any, will be created.
— Creative Commons, FAQ

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Guided Exercises
1. Which module of the Creative Commons license system is part of all six Creative Commonslicenses?

2. Which module of the Creative Commons license system requires the distribution of a work
under the same conditions?

3. How does CC0 differ from the six CC core licenses?

4. What is the difference between “international” and “ported” licenses?

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Explorational Exercises
1. Is it possible to place a photograph of a work that is in the public domain under a CC license?

2. Can an author publish his novel, in which he incorporates a Shakespearean sonnet in its
entirety, under a CC license?

3. A user publishes a photo of herself on her website under a CC license. Can she prevent the
distribution of this image by invoking her personal rights?

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SummaryFounded in 2001, the Creative Commons organization aims to support the sharing and use ofcreative works, i.e. works subject to copyright, with the help of free legal tools. The focus is onfour modules (Attribution, NonCommercial, NoDerivs and ShareAlike), which are combined in six
so-called core licenses and can be selected by authors for their works.

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Answers to Guided Exercises
1. Which module of the Creative Commons license system is part of all six Creative Commonslicenses?
The “Attribution” module, abbreviated “BY.”
2. Which module of the Creative Commons license system requires the distribution of a work
under the same conditions?
The “Share Alike” module, abbreviated to “SA.”3. How does CC0 differ from the six CC core licenses?
With CCO, an author does not secure certain rights — as with the other CC licenses — but
waives all rights to the work within the scope of the possibilities of the respective jurisdiction.
This principle of “no rights reserved” corresponds to the designation of the work as publicdomain.
4. What is the difference between “international” and “ported” licenses?
Until version 3.0, Creative Commons offered variants of its licenses that took into account the
specifics of a regional or national jurisdiction. Since 4.0, CC has dispensed with these so-called“ported” versions and recommends the globally valid “international” version of the respective
license.

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Answers to Explorational Exercises
1. Is it possible to place a photograph of a work that is in the public domain under a CC license?
This depends on whether the photograph fulfills criteria according to which it is itself protectedby copyright. In other words, the photograph itself must be recognizable as a creative work andworthy of protection, for example through perspective, background, filters, etc. If this is thecase, it can be placed under a CC license and the conditions of the CC license then apply.
However, the original part, i.e. the actual motif, remains in the public domain.
2. Can an author publish his novel, in which he incorporates a Shakespearean sonnet in its
entirety, under a CC license?
Yes, but only the author’s own creative parts of the novel are subject to the CC license chosen
by the author. The sonnet, which is in the public domain, remains in the public domain.
3. A user publishes a photo of herself on her website under a CC license. Can she prevent the
distribution of this image by invoking her personal rights?
By publishing a photo under a CC license, an owner generally agrees to its distribution. A limit
is reached when the use of the photo violates the personal rights of the owner, for example
when the image is grossly distorted or used for advertising or in a political context without theowner’s consent. The personal rights of the owner are not affected by the regulation of therights of use by the CC license, so that in such cases she can take legal action against the use ofher photo.

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053.3 Other Open Content Licenses
Reference to LPI objectives
Open Source Essentials version 1.0, Exam 050, Objective 053.3
Weight1
Key knowledge areas• Understanding licensing for documentation• Understanding licensing for data sets and databases• Understanding the rights granted by open content licenses• Understanding the obligations created by open content licenses
Partial list of the used files, terms and utilities• GNU Free Documentation License, version 1.3 (GFDL)• Open Data Commons Open Database License (ODbL)• Community Data License Agreement – Permissive, version 1.0 (CDLA)• Community Data License Agreement – Sharing, version 1.0 (CDLA)• Open Access132|

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Lesson 1
Certificate:Open Source Essentials

Version:

1.0

Topic:

053 Open Content Licenses

Objective:

053.3 Other Open Content Licenses

Lesson:1 of 1Introduction
Previous lessons have already introduced the concept of open content, focusing on Creative
Commons licenses. In addition to Creative Commons licenses, however, there are other open
content licenses, some of which relate to specific content and are also regularly used for “byproducts” (such as documentation) of open source projects.

Licenses for (Software) Documentation
Large software repositories regularly contain documentation or manuals for the software in
addition to the code. Documentation usually contains various copyrightable elements, such as
explanatory texts, illustrative graphics, or code examples. Open source licenses that apply to thecontents of a repository are generally also applicable to such texts if no other information isavailable; for example, GPLv3.0 applies to “any copyrightable work” and is not limited to code.
However, documentation is often subject to different license conditions. This can make sense forvarious reasons, because documentation is produced and used differently from code. The license
conditions of a strict copyleft license for computer programs may, for instance, prevent the
adoption of individual parts of the documentation for other programs. It is also unclear what is

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meant when the “source code” is to be provided for GPLv3.0-licensed documentation. In addition,
it used to be common practice to distribute printed versions of documentation or manuals for
programs. This circumstance can be better taken into account by specific documentation licenses(for example, if some license obligations are linked to a certain number of distributed copies).
Creative Commons licenses are often used for documentation, but there are also special copyleftlicenses for documentation, such as the Free Documentation License (FDL), which explains its
purpose in its preamble:
The purpose of this License is to make a manual, textbook, or other functional and useful
document “free” in the sense of freedom: to assure everyone the effective freedom to copy
and redistribute it, with or without modifying it, either commercially or noncommercially.
Secondarily, this License preserves for the author and publisher a way to get credit for theirwork, while not being considered responsible for modifications made by others.
This License is a kind of “copyleft,” which means that derivative works of the document mustthemselves be free in the same sense. It complements the GNU General Public License, which
is a copyleft license designed for free software.
We have designed this License in order to use it for manuals for free software, because free
software needs free documentation: a free program should come with manuals providing thesame freedoms that the software does. But this License is not limited to software manuals; it
can be used for any textual work, regardless of subject matter or whether it is published as a
printed book. We recommend this License principally for works whose purpose isinstruction or reference.
— Free Documentation License, Preamble

The license is very specific to documentation; for example, it also addresses printed versions. In
particular, a copyleft documentation license explicitly does not affect the code with which it isdelivered. Although it would also be possible to distribute documentation under GPLv3.0 together
with MIT-licensed code: Since in this case there would be two independent works, the GPLv3.0 of
the documentation would not result in the code having to be licensed under GPLv3.0. But a
dedicated license for documentation provides more clarity in this regard.

Licenses for Databases
There are also special licenses for databases. Among other things, these licenses take into accountthe use of a database as a resource for a program and the special features of copyright protection
for databases.

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What the Term “Database” Applies to
In copyright law, a distinction is made in some legal systems (including in Europe) between
database works that, like other copyright-protected works (images, texts, etc.), enjoy protection on
the basis of personal intellectual creation (selection and arrangement of elements), and databases
for whose production (procurement, verification, presentation) a substantial investment was
required (database right).
In both cases, the object of protection is a collection of independent elements (such as distinct
works or items of data) that are systematically or methodically arranged and individuallyaccessible electronically or by other means. The copyrightability of the elements themselves is notimportant, so they can also be mere numerical values.
A collection of data can therefore be protected by copyright as a database work or under databaseright (in the EU). For a database work to be protected, the arrangement and selection of theelements must express a personal intellectual creation. This is unlikely to be the case for datacollections that are used as the basis for software — but these can be protected under databaseright. To earn this right, a substantial investment must have been made in the collection andarrangement of the elements. This investment can also consist of time and human resources.
Various licenses are now available for databases and data collections that better cover the use ofdata than “classic” open source software licenses. Let’s take a look at the distinction using an
example.
As part of an academic research project, all of an author’s poems are to be collected and published
on a website, where they are sorted alphabetically by title and can be accessed individually.
However, the project requires that the relevant copyrights for the distribution and reproductionof the poems are obtained from the author. License fees are paid for this.
The license fees may constitute a “substantial investment.” Since the poems are individually
retrievable and arranged systematically (according to the alphabet), the database serving thepoems is protectable under database right. However, the elements (poems) were not specificallyselected (the selection was done on the basis of completeness) and the arrangement is notcreative, but purely systematic. There is therefore no personal intellectual creation in relation to
the database, so that the database does not qualify as a database work.
If, on the other hand, the poems had been arranged and selected according to certain
criteria — for example to document certain motifs in the author’s work in the context of thecreative period — a personal intellectual creation could exist, and then this collection of poems
would be protectable as a database work.
However, the two categories are treated differently under copyright law, in particular with regard

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to the term of protection: databases under the database right are protected only 15 years after
production/publication, as opposed to 70 years after the death of the author for database works.
Delimitation for Data
The data contained (in our example, the poems) must always be considered separately from thedatabase as a whole, because they may (but need not) be eligible for protection in their own rightand may therefore be subject to different license conditions. For example, the collection of poems
may be subject to the Open Database License (see below), while the individual poems may besubject to a Creative Commons license or a proprietary license.
Delimitation for Database Management System (DBMS)
In addition, the software for managing the data, the so-called database management system(DBMS), which is not considered part of the database under copyright law, but as a means ofaccessing the data, must be considered separately under copyright law. Such applications — suchas MySQL, PostgreSQL, MariaDB, and others — are to be considered separately as computer
programs and are protectable as such.
Datasets for Training Machine Learning Models
Various collections of data can be downloaded from websites such as huggingface.co or
kaggle.com, for example to train machine learning models. Such collections, also known asdatasets, are usually subject to database right, provided a “substantial investment” has been madein their production (which is usually not readily apparent from the outside).
The term “dataset” is somewhat vague because it can refer to a line in a database — i.e., an entry
or a definable element — but also to collections of data or datasets.

Open Database License (ODbL)
These distinctions are also visible in the Open Database License (ODbL), a widely used license in
the database sector. The ODbL was developed by Open Data Commons, a project of the Open
Knowledge Foundation. The license makes a clear distinction in its preamble between protectionof the database and protection of the individual contents of the database. The license refers only
to the former, while the contents can also be licensed elsewhere independently of this.
Of course, it is still possible to choose the same license for the database and the content, e.g., tocompile a collection of works licensed under CC-BY-4.0 in a database that is in turn licensed under
CC-BY-4.0.
The best license for the database depends on the objectives of the database producer. To stay with

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our example of the poetry collection: If the poetry database is to be modified at will and may also
be distributed under other license conditions, the ODbL would not be the right choice. This isbecause the ODbL contains a copyleft for databases, which means that a database derived from an
ODbL-licensed database (e.g. a database that adopts all elements and the arrangement of theelements of the original database and adds others) may be redistributed only under the same
conditions. In this case, a Creative Commons license with editing rights (e.g. CC-BY) is a better
choice.
The ODbL also makes it clear that it in no way applies to computer programs that manage thedatabase (i.e., a DBMS): “This License does not apply to computer programs used in the making or
operation of the Database.”
However, the license stipulates that a work created from the contents of the database andavailable for public use (a so-called produced work) must at least indicate which database (notDBMS) was used for it and that the the database itself may be used under the conditions of the
ODbL. An example of such a produced work is a street map created from the coordinates collectedin the database.
If one of the known (software-specific) copyleft licenses such as GPLv3.0 were used for a database,it can be assumed that a computer program that uses the database (e.g. for a store system) could
be distributed only under the terms of GPLv3.0. The license of a DBMS, on the other hand, is likely
to be independent of the license of the database because the DBMS is not considered a “derived
work” of the database; it merely enables access and editing and is therefore an independent work.

Community Data License Agreements (CDLA)
The Community Data License Agreements (CDLA), a project of the Linux Foundation, also focuseson the licensing of data (as distinct from software). Training data collections for machine learning
systems can also be the subject of CDLAs.
Our communities wanted to develop data license agreements that could enable sharing ofdata similar to what we have with open source software. The result is a large scalecollaboration on licenses for sharing data under a legal framework which we call the
Community Data License Agreement (CDLA).
These licenses establish the framework for collaborative sharing of data that we have seen
proven to work in open source software communities.
— CDLA website (cdla.dev)

The CDLA is therefore based on a framework that takes into account different levels of licensing
issues, especially when data is compiled from multiple sources by different contributors. In our

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example, this could be a collection in which different authors contribute their own poems to build
a common poetry database.
CDLA distinguishes between the “inbound license” for data that is added to the collection and the“outbound license” for the use of the data. At a third level, it specifies requirements for theorganization that hosts or holds the data.
To stay with the poetry example: An author who contributes their poem would be guided by the
specifications for “inbound licenses”. The “outbound license” concerns the conditions agreed uponby the editors of the poetry collection as a whole.
Similar to the open source licenses for software, CDLAs are available in the permissive and sharing
categories, which we will briefly introduce. A visit to the aforementioned kaggle.com or
huggingface.co websites will give you an impression of which licenses are used for databases ordatasets: For example, you can use filters to find out which data collections are offered under
CDLA.
Community Data License Agreement — Permissive
Version 2.0 of the permissive CDLA has been available since 2021 and is much more concise andclearly formulated than version 1.0.
Version 1.0 grants rights to use and publish the licensed data, including the publication of socalled “enhanced data,” which also includes edits or additions to the dataset. When passing on or
publishing the data, basic license obligations must be observed; among other things, the license
text must be passed on, changes must be marked, and copyright notices must be retained. The
data can also be passed on under additional or other license conditions.
In version 2.0, the wording “enhanced data” is no longer used; instead, the granting of rights isformulated more precisely:
A Data Recipient may use, modify, and share the Data made available by Data Provider(s)under this agreement if that Data Recipient follows the terms of this agreement.
— Community Data License Agreement - Permissive, version 2.0

The only condition for sharing the data in version 2.0 is the passing on of the license text or a linkto the license text.
Community Data License Agreement — Sharing
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under the same conditions.
The Data (including the Enhanced Data) must be Published under this Agreement inaccordance with this Section 3;— Community Data License Agreement -- Sharing, version 1.0

Open Access
One term that is often used in connection with open content is open access. Although the term is
not defined in the legal sense, the declaration of the Budapest Open Access Initiative (BOAI) makes
the intention behind open access clear. The initiative arose from a conference in Budapest in 2001
and summarizes the international efforts for open access:The literature that should be freely accessible online is that which scholars give to the world
without expectation of payment. Primarily, this category encompasses their peer-reviewed
journal articles, but it also includes any unreviewed preprints that they might wish to put
online for comment or to alert colleagues to important research findings. There are manydegrees and kinds of wider and easier access to this literature. By “open access” to thisliterature, we mean its free availability on the public internet, permitting any users to read,
download, copy, distribute, print, search, or link to the full texts of these articles, crawl themfor indexing, pass them as data to software, or use them for any other lawful purpose,
without financial, legal, or technical barriers other than those inseparable from gaining
access to the internet itself. The only constraint on reproduction and distribution, and theonly role for copyright in this domain, should be to give authors control over the integrity of
their work and the right to be properly acknowledged and cited.
— Declaration of the Budapest Open Access Initiative

Open access therefore refers in particular to free access to scientific literature and other content
on the internet. The open access movement originated in the 1990s with the aim of making
scientific publications available to the general public. Open access therefore does not refer to a
specific license or certain licensing conditions, but rather to a concept of licensing.
When an article is published with open access, the first step is to choose an open content license,such as one of the Creative Commons licenses. However, the choice of a CC license is notmandatory for open access. Over the years, a categorization of different open access strategies hasdeveloped, which also take dual licensing into account — for example, granting a comprehensive
license to a publisher while simultaneously the author offers the content for download on theirown website.
Both the BOAI and the Berlin Declaration that followed two years later are important milestones

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in the open access movement. The preamble to the Berlin Declaration states:
In accordance with the spirit of the Declaration of the Budapest Open Access Initiative, the
ECHO Charter and the Bethesda Statement on Open Access Publishing, we have drafted the
Berlin Declaration to promote the Internet as a functional instrument for a global scientificknowledge base and human reflection and to specify measures which research policy
makers, research institutions, funding agencies, libraries, archives and museums need toconsider.
— Berlin Decalaration 2003

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Guided Exercises
1. Can “classic” open source licenses also be used for documentation and databases?
Yes
No
It depends, there is no clear answer
2. Does it make sense to use separate licenses for documentation? Why?

3. Does it make sense to use separate licenses for databases? Why?

4. Which of the following licenses are suitable for documentation?
CC-BY-4.0
FDL
ODbL
GPL-3.0
BSD-3-Clause
5. What is meant by the term “open access”?

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Explorational Exercises
1. Are there specific licenses for fonts?

2. Briefly explain two open access strategies or models.

3. What is meant by the “open definition”?

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Summary
In addition to the well-known Creative Commons licenses, there are other concepts for licensing
content that are even more specifically tailored to the respective data types: For software
documentation or databases, the FDL or ODbL licenses are available that take into account thecharacteristics of these types of works. This lesson provides an overview of some of these licenses
and also addresses the concept of open access.

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Answers to Guided Exercises
1. Can “classic” open source licenses also be used for documentation and databases?
Yes

X

No
It depends, there is no clear answer
2. Does it make sense to use separate licenses for documentation? Why?
Yes, because they usually contain other content than the program itself. They also regulate how
printouts of the documentation are to be handled, for example.
3. Does it make sense to use separate licenses for databases? Why?
Yes, it can be useful. In particular, a specific database license can achieve a copyleft effect forthe database without the copyleft affecting the surrounding code. In addition, database licenses
address specific provisions that copyright law provides for the protection of databases.
4. Which of the following licenses are suitable for documentation?
CC-BY-4.0

X

FDL

X

ODbL
GPL-3.0
BSD-3-Clause
5. What is meant by the term “open access”?
The term describes free access to scientific literature and other content on the internet.

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Answers to Explorational Exercises
1. Are there specific licenses for fonts?
Yes, there is, for example, the SIL Open Font License (OFL), which contains a copyleft
specifically for fonts, but this has no effect if fonts are used unchanged.
2. Briefly explain two open access strategies or models.
In the “Gold” open access strategy, the publication is made available directly by the publisher
under an open content license, usually (but not exclusively) using Creative Commons licenses.
The “Green” open access model applies when the publisher does not distribute the publication
under open access, but the author is given the opportunity to make the publication available
for download, such as on their website under an open license.
3. What is meant by the “open definition”?
The “open definition” is a common understanding, formulated by the Open Knowledge
Foundation, of the term “open” in “open data,” “open knowledge,” and “open content.” Thedefinition describes in particular the basic freedoms that must be granted if a license is to be“open” in the sense of the definition. These include access, use, editing or modification, andsharing.

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Topic 054: Open Source Business Models

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054.1 Software Development Business Models
Reference to LPI objectives
Open Source Essentials version 1.0, Exam 050, Objective 054.1
Weight2
Key knowledge areas• Understanding goals and reasons to release software or content under an open license• Understanding common business models and revenue streams for organizations developing
open source software and open content• Understanding the implications of using open source software as components in larger
technology products and services• Understanding the impact licenses have on a software development business models• Awareness of cost structures and investments needed for open source softwaredevelopment business models
Partial list of the used files, terms and utilities• Paid development• Open-core and paid add-ons• Freemium• Enterprise and community versions• Self-hosted distribution• Subscriptions• Customer support

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Lesson 1
Certificate:Open Source Essentials

Version:

1.0

Topic:

054 Open Source Business Models

Objective:

054.1 Software Development Business Models

Lesson:1 of 1Introduction
Traditionally, companies that distributed proprietary software (also known as closed source
software) had a relatively straightforward business model: They sold a license to use the software,
either as a one-time fee or on an ongoing basis in a subscription model.
But over the decades, the market for software has changed radically, and customers today expect
to pay a few dollars for an app and receive free updates for life.
As a result, the old-school approach to proprietary software isn’t profitable anymore, and evencompanies that used to build their entire business model around selling software licenses havediversified into vendor integration, support, services, Software-as-a-Service (SaaS),
cloud/container hosting, and hardware products that run software (phones, laptops, servers,
printers, cars, smart watches, etc.).
In contrast, free and open source software licenses give anyone the right to use, study, modify,
and redistribute the software without paying a fee. So, businesses based on open source never had
the option to sell a license to use the software. You shouldn’t expect to simply take the work ofothers from an open source project and make a huge profit giving that publicly available work to148|learning.lpi.org|

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your customers, because they can get the same software for free directly from the project. Instead,companies that provide free and open source software use alternative business models. The mostsuccessful software business models often combine multiple forms of customer value.
This lesson looks at why a company would choose some of these software business models with
open source software, and the trade-offs in these options.

Goals and Reasons to Release Software or Content Under anOpen License
There are many reasons developers choose to build a business on open source code: The software
may meet a need, solve a problem, or provide some features that the developers deliver tocustomers. A company can save time and money by sharing the work on software with otherdevelopers, instead of writing the same software from scratch. Participating in the project is aninvestment that hopefully pays off in usable, stable, reliable, secure, well-maintained software.
Many open source developers hope to get bug fixes from their customers. Some customers taketheir contributions to an even higher level by adding new features, porting the software to a newenvironment, or making other significant improvements. Both bug fixes and higher-level
improvements enhance the original software. If customers contribute them back to the original
developers, the changes might make the code more desirable to other potential customers andencourage its adoption.
But a company can’t expect contributions and attention just by placing its code on a site such as
GitHub or GitLab. It’s one thing to encourage developers to join a project, but more challenging tokeep them enthusiastic about it — so don’t underestimate the amount of work that community
contributions call for. A company needs to put effort into recruiting developers, mentoring them,motivating them, and checking their code for flaws.
Another reason to open the code is to create an industry standard. Sharing code in an open
manner could lead to better interoperability and other benefits. The team that developed the code
has valuable expertise that might allow them to direct the future of the project and get paid forsupporting others who use the code.
Some companies open their code in order to create trust among customers. First of all, customers
know they can continue to use and improve the code if the company fails or decides to enter adifferent market and abandons the code. Second, customers can check the quality and security of
the code for themselves or ask an independent expert to do an audit, which is usually not possible
with closed, proprietary software.
Finally, a company might have adopted a code base that is already open source, planning to build

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a commercial business on it. The license might require the company to distribute the source codeof its changes to any end-user of the program.
In short, some reasons to open a company’s code are:• Building on an existing free software project• Benefiting from customer innovation and contributions• Creating trust among customers• Promoting code as an industry standard

Common Business Models and Revenue Streams
The software industry, over the past several decades, has discovered many business models
appropriate for proprietary as well as open source businesses. This section focuses on the mostpopular ones in current use among open source developers.
One business model, common in both proprietary and open source software, is to charge forsupport. Customers might have trouble installing and configuring the software, fixing bugs as they
are found, adding new features for their exclusive use, and managing their systems. The staff who
developed the software are excellent sources of support. In fact, this staff is probably alreadyoffering free support on forums where the software is discussed.
Thus, in the support model, a customer pays a vendor to install the open source software on thecustomer’s hardware (called a self-hosting distribution) or gets access to the software on thevendor’s hardware (a cloud-based model). Support contracts ensure that customers will get timely
help from the company for their more complex needs. Companies using this model generally offer
retainers, which clients pay for on a regular basis.
Another business model for proprietary software — really a set of overlapping models — is called
freemium, a term popularized in 2009 by author and editor Chris Anderson, and based on a mucholder business model known as razor and blades. In the razor and blades model, customers payvery little for the base product (for example, a razor or a printer), and then pay a premium fornecessary components designed to wear out (blades for the razor, ink cartridges for the printer).
In the freemium model, customers can use a product at a certain level cost-free, and areencouraged to pay for more features if they find the product useful. You probably know online
news sites that offer a certain number of free articles and ask readers to subscribe for full accessto their sites; this is a well-known example of a freemium model. Another example is a gaming
platform that provides the base game for free, but charges money for specific inventory.

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Other proprietary software companies base their freemium model on time: Try out the software
free for three months and then pay in order to continue using it.
Proprietary software companies sometimes use a version of the freemium model known as open
core. In open core, certain basic features (the “core” of the product) are open source, andadditional proprietary features can be licensed.
Often, the open part is fully functional but works best for researchers or individual users, andbecomes hard to manage when many people are sharing it across an enterprise. Therefore, theproprietary features might include convenient web interfaces for administration, tools foraccounting and collaboration, and other things of particular interest to large sites.
Even though open core business models use some open source software, customers are smart
enough to recognise that the whole product is actually proprietary. So, while open core may havethe advantage of building on existing open source project, it fails to provide any other advantagesof open source software. An open core business model doesn’t build trust with customers, inspirethem to contribute to the base software, give customers access to examine the code, build a
network of skilled developers outside the main company, or work as an industry standard. Even
worse, the open core development model has the same costs of developing, without the benefits
that make it worthwhile. Companies who try an open core business model are generally
disappointed in the results, and many later switch to a pure proprietary model.
Companies can also build a web service on top of an open source or proprietary code base, in the
Software as a Service (SaaS) model. Customers pay on a monthly or yearly basis.
Many companies who run SaaS web services or offer mobile apps make money throughadvertising. Some companies also collect data on users through the service or app and sell thisdata to third parties who can use it for advertising. Advertisements can be seen as annoying,
though. Selling data is controversial, and some countries put restrictions on data collection.
Finally, companies might develop and release open source software without trying to derive any
revenue from it at all. This model is available to companies who get revenue from things besides
the software. For instance, automobile companies collaborate to create large bodies of free
software to run in their cars (which nowadays are thoroughly computerized).
Major software companies who derive their revenues from proprietary offerings, such as Google
and Amazon, sometimes release administrative software or other useful tools as open source,
because these open source tools are not central to their core business. The organizations who
release the code under an open license benefit from feedback, bug reports, and featureenhancements provided by the open source community.

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Using Open Source Software in Other Technologies and Services
A lot of companies incorporate open source software into their products or web platforms. Afterall, open source software is free! But that’s not the most important reason (and perhaps not even agood reason) to adopt it. More importantly, a lot of this software is high-quality (although thedevelopment team should vet it carefully before adopting it) and may even be an industry
standard.
Another advantage of open source software is that it will continue to be available if the developers
or the community around it go away.
But free and open source software brings responsibilities. This section will quickly list the main
issues to consider before adopting it.
The first issue applies to any third-party software or tool under consideration for adoption: Will itmeet the users' needs now and as the company evolves? Is the software supported by a strong
community that can offer technical support and continue to develop the software? Does thesoftware suffer from significant security vulnerabilities?
Next, managers must consider the company’s responsibilities if it incorporates an open source
project into its own software. If developers build new code around the open source code, theyshould check what they are required to do by the license from the open source software. Somelicenses require developers to distributed the source code of their own changes to their end-users
under the same free license as the original code base.
Even if a developer isn’t required to distribute their modified source code, and is creating aproprietary product on top of the open source code, the developer might want to contributecertain things back, such as bug fixes and enhancements to the open source code. By contributing
these fixes and enhancements, the contributing developer allows the project to incorporate them
(if the core developers choose to do so) and maintain them. Developers who don’t contributeenhancements back might have to re-apply the fixes and enhancements every time they upgrade
to a new version of the original code.
Because of this dependency, and for other reasons, company staff should consider becoming
active members of the community that develops the code. Developers can learn a lot about thecode by participating, and can help set the direction for future development. Of course, theorganization should pay for the time developers spend in community activities. For a company
that is serious about using free software, it is not cost-free.

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Considerations of Open Source Software from a Customer’s
Perspective
Opening code is very beneficial to customers for several reasons, but implies a different
relationship between the company and its customers. The customers should understand thebenefits as well as the implications of the relationship.
The main benefit to the customer, mentioned earlier in this lesson, is that they can have moretrust in the software. They know that it won’t go away. Many proprietary companies shut down ortake off suddenly in a new direction, abandoning customers with perhaps only a short time tomigrate to a product the customers might not like. Open source software, in contrast, doesn’t
depend on any single organization. If the project matters, other people in the community willcontinue the project when the original developers move away.
Customers can also check the quality and security of open source software. They can determine
how easily they can add features of their own or port it to a new environment.
Because the source code in an open source project is open for all to examine, a wide range ofdevelopers can familiarize themselves with it. On a project that has an active community, many
people provide support on the forum. Often, it’s easy to hire people to support the software or toadminister and use it within the company, because the new employees already know the code.
It’s very reassuring to customers, who depend on code for day-to-day functioning, to know thatthey can fix a bug themselves or hire someone to do so. An obscure bug that affects only a few
customers might take years to be fixed by the core development team, a constant frustration tousers of proprietary software. In addition, when the source code is available, a bug and its
suggested fix might be identified more quickly.
What about the relationship between the company and the customer? The company can choose to
set up a relationship exactly like one offered by a typical proprietary software company,
providing the customer with regular updates and a support contract. The customer never needs tolook at the source code or join the community forums.
But most customers would benefit from the unique opportunities offered by open source projects.
They can allow their own developers to contribute both information and code. Such participation
deepens their staff’s understanding, helps them recruit new staff, and gives them a voice in future
development.

Cost Structures and Investments
Programmers are in high demand, so any software effort is going to be expensive. People who

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know major open source projects are even more in demand, because those code bases are used so
widely.
An open source project offers potential cost savings because different organizations andindividuals can combine their efforts in a common code base. But running such a project
introduces new costs.
If a company opens a project that was developed in-house, the company needs to invest in making
it serve a larger (possibly worldwide) community. Some functions that met the company’s narrowbusiness needs might need to be rethought so they serve other businesses as well.
If the code is poor or awkward, a company probably shouldn’t open it. Potential contributors aswell as potential customers will be repelled by the quality. It behooves developers to fix these
problems anyway, because poorly coded software is brittle: It is hard to update with new features
and tends to develop complex bugs that are hard to fix. These problems are called technical debt,
and the sooner they are fixed, the better it is for all users.
Finally, it’s surprising how often a company has embedded trade secrets, passwords, personalreferences to individuals, or other sensitive information in code. Developers have to invest time instripping out such vulnerabilities. Passwords, API keys, certificates, and cloud access credentials
should never be in code anyway; they should be managed externally through a secure service.
Let’s say that a company has opened its code, and is hoping to benefit from outside contributions.
Some customers will pay developers for maintenance and new features. Others will put their own
developers on the project, but the core development team has to allocate time to support them.
The core development team needs to educate outsiders about the code and the associated coding
standards. This team should also guide outside contributors about what to add and where to sendback comments on their code.
Keep an eye out for outsiders who show talent. These individuals could be valuable recruits to thecore team. They might like to join the team, and they come with considerable knowledge.
When one team of developers is paid, while other people are volunteering their time, thevolunteers might feel exploited or ask why they should help. Each contributor, whether anindividual volunteer or an organization, has to undergo the types of thinking described earlier inthis lesson to decide why they are contributing.
Free code is not cost-free, even if entails no licensing costs. It is simply a different model fordevelopment.

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Guided Exercises
1. How does open source code improve customer trust in the software?

2. Why are companies tempted to try an open core business model, and why does the model failto deliver the benefits of open source software?

3. What is self-hosted distribution?

4. What are typical types of help that developers give to outside contributors to their open source
projects?

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Explorational Exercises
1. You are considering basing a proprietary product on an open source project. What factors
would you consider in order to make the decision?

2. You have built several products, for which you charge a subscription, on top of an open source
project. What will you do if the open source license requires you to contribute all your code
back to the project? Also, you added support for some new communication protocols to theopen source project to support your proprietary needs. If you have a choice, will you ask theopen source project to integrate this protocol support into their core code?

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Summary
In this lesson, you learned the value of opening source code. You reviewed the common businessmodels in use today, and the importance of understanding the impact of the code’s license. You
read about issues to consider when incorporating open source code into your enterprise, and how
open source benefits your customers. You also learned how costs of open source development
differ from those of proprietary software.

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Answers to Guided Exercises
1. How does open source code improve customer trust in the software?
Customers can check the quality and security of the code. They can also trust that they cancontinue using the code if the original developers stop supporting it.
2. Why are companies tempted to try an open core business model, and why does the model failto deliver the benefits of open source software?
At first glance, it seems like open core should offer all the benefits of open source software,
while allowing a company to still use a proprietary business model that sells a license to use thesoftware. In practice, an open core business model fails to deliver the advantages of open
source, while still having all the increased costs of open development.
3. What is self-hosted distribution?
Self-hosted distribution means a version of software that can be run on a customer’s own
equipment.
4. What are typical types of help that developers give to outside contributors to their open source
projects?
Developers on a project typically educate and mentor outside contributors, and check that theircontributions meet the team’s quality and coding standards.

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Answers to Explorational Exercises
1. You are considering basing a proprietary product on an open source project. What factors
would you consider in order to make the decision?
First, decide whether the open source software meets your needs. Check its quality, security
flaws that have been publicly reported, and the health of the community around it. Check thelicense carefully to see whether it requires you to share your modifications to the code.
Determine how much you want to participate in the open source project’s community and how
you’ll define the roles that your developers will play in that community.
2. You have built several products, for which you charge a subscription, on top of an open source
project. What will you do if the open source license requires you to contribute all your code
back to the project? Also, you added support for some new communication protocols to theopen source project to support your proprietary needs. If you have a choice, will you ask theopen source project to integrate this protocol support into their core code?
If the project does not require you to share code changes, you probably won’t do so because
you can charge a subscription more easily for a proprietary product. If you do have to shareyour code, offer a subscription to a self-hosted distribution. Even if you don’t need to shareyour code, you probably want to ask the project to integrate your support for communication
protocols so that you don’t have to re-implement that support each time you install a newrelease of the open source code.

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054.2 Service Provider Business Models
Reference to LPI objectives
Open Source Essentials version 1.0, Exam 050, Objective 054.2
Weight2
Key knowledge areas• Understanding common business models and revenue streams for organizations providing
services related to open source software and open content• Understanding the impact licenses have on a service provider business models• Understanding service level objectives and service level agreements• Understanding the need for security and privacy protection• Awareness of cost structures and investments needed for open source software service
business models
Partial list of the used files, terms and utilities• Hosted services• Clouds• Consulting• Training• Hardware sales• User support• Terms of Service (ToS)• Service Level Objectives (SLO)

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Lesson 1
Certificate:Open Source Essentials

Version:

1.0

Topic:

054 Open Source Business Models

Objective:

054.2 Service Provider Business Models

Lesson:1 of 1Introduction
Service providers are the backbone of any company or organization that operates in any way via
a network. From the Internet Service Provider (ISP), which provides access to the global internet,
to specialized applications such as e-mail or customer management, it is software-based services
that make actual business operations possible.
Open source software is a component of many different service provider business models. For
example, an open source operating system could form the basis of a hosting service business. An
open source orchestration tool could be the backbone of an Infrastructure-as-a-Service (IaaS) or
Platform-as-a-Service (PaaS) business, such as a public cloud provider or container platform. An
open source application could be delivered online as Software-as-a-Service (SaaS). Some service
providers also offer supplementary services related to open source software, such as consulting,training, or customer support.

Revenue Streams
When the service is based entirely or in large part on open source software, we can call it an open
source business model. Because open source software can be downloaded and used without paying

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a fee, open source service business models have developed specific products and services
depending, among other things, on the proportion of free software in the actual product.
If the entire software is under a free license, a business model can consist of hosting, i.e.,
providing the software on a reliable and secure platform. This eliminates the effort and risk ofcustomers operating their own servers. In return, customers pay the service provider fees for use.
The fees may be related to the number of user accounts, the volume of data that is stored ortransferred, or certain time intervals. In some cases, multiple different providers offer paid
services to the same open source software.
This popular business model often involves subscriptions, where customers pay a monthly or
annual fee for access to the service. Access is often combined with additional services orfunctions. Providers may offer multiple tiers of subscriptions, charging a higher rate for morefeatures, more users, more comprehensive services, or a stronger guarantee of reliability. Some
providers may also offer a basic level of the service for free, a variation on the “freemium” model.
Another popular revenue stream for the open source service provider business model has always
been to offer support. Support includes advice, documentation, and training for users who haveproblems using the software. If the customer prefers to host the free software on their own
servers, installation in particular can often be difficult because the user may need to install othersupporting tools and libraries, may not know where to put them to make all the pieces work
together, or may run into problems on their particular hardware and operating system.
Therefore, support and training from a service provider is valuable.
Extra services, such as additional functional or security-related features, can also be developed
and provided on a customer-specific basis. Such features or adaptations of the software to acustomer’s very specific requirements are a sophisticated and lucrative addition to the businessmodel. It is then up to the service provider and the customer to decide whether the additions flow
back into the basic project as free software or become proprietary.
A few open source projects offer a dual-license model. The software is available under a free
software license, which serves many users' needs. But some users want to incorporate thesoftware into a proprietary product, which cannot be done under a reciprocal license. Therefore,a standard copyright-based license is provided for these users. The dual-license model is mosteffective for databases, because many companies would like to offer a feature-rich and efficient
database as part of a proprietary software product.
In an advertising revenue model, customers do not pay for access to the service. Instead, theservice provider displays ads to the customers using the service and charges companies to place
their ads. Open source service providers often avoid using proprietary ad services due to concerns
about user privacy. However, alternative open source ad services do not engage in invasive ad

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tracking.
In a commission-based model, the service provider receives a percentage or fee for managing
transactions through their online service. This model is the basis for most e-commerce sites, travelbooking sites, and payment processors. Many open source projects in this space are generalpurpose platforms intended to be either self-hosted by the service provider or offered as asecondary commission-based service, where the customer-facing website pays a percentage or fee
for a hosted version of the open source platform.
An open content business model involves creating and distributing content under licenses such as
Creative Commons so others can freely use, modify, and share it. Users are encouraged tocontribute to the content, improving it over time. While the content itself is free, revenue can begenerated through complementary products or services such as donations, displaying ads,
offering freemium features, selling related merchandise, or providing consulting, training, or
support services.

Choosing Between Hosted and Self-Hosted Services
Hosted services are ideal for organizations looking for ease of use, lower initial costs, scalability,and professional security management without the need for deep technical expertise. However,these services come with potential downsides in terms of control, customization, data privacy, anddependency on the provider.
Hosted services usually require minimal setup, and the service provider handles maintenance,
updates, and system security. They often make global data centers available, providing better
performance and reliability for international users. Service providers can scale resources up or
down based on demand with minimal effort from the customer. Moreover, hosted services often
have dedicated security teams to manage and respond to threats, and service providers may offer
compliance with various regulatory standards.
On the other hand, hosted services store customers' sensitive data off-premises, which may raise
concerns about data privacy and trust. A shared hosting environments can pose additional
security risks. The service provider’s outages or downtime directly affect the customer’s service
availability. Depending on a single provider can be problematic if the provider changes terms or
discontinues the service.
Self-hosted services are thus suitable for organizations with the necessary technical expertise andresources to manage their infrastructure. However, self-hosting involves higher initial costs,
ongoing maintenance, and scalability challenges. The choice between hosted and self-hosted
services ultimately depends on each customer’s needs, technical capabilities, budget, andpriorities for control, customization, and data privacy.

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Impact of Licenses
Basically, open source software licenses work well with service provider business models because
the customer doesn’t expect to own the software that provides the service. Instead, they’re paying
for access to the service.
On the other hand, the use of open source software in services such as IaaS, SaaS, or PaaS raises
legal issues that are often not clarified. Only a few licenses, notably the GNU Affero General Public
License, explicitly regulate the use of free software “in the case of network server software.”With other popular licenses — both the more restrictive copyleft licenses such as the GNU General
Public License, and permissive licenses such as the BSD licenses — there is room for discretion as
to what can be considered "'copying,`" “conveying,” or “distribution” when the software is usedover the network. Decisions about whether and in what form the source code is to be madeavailable to the application or attribution requirements depend on such definitions. The
connection with proprietary software components or the licensing of self-developed
supplementary components must also be legally clarified. For these reasons, it is crucial in thecontext of service provider business models to clarify licensing issues relating to the use of free
software.
It is good practice for service providers to publicly list all the open source software they use
together with their respective license, even when they aren’t legally required to do so.

Considerations of Security and Privacy Protection
The success of a service provider business model relies heavily on a satisfying customer
experience, especially with open source software, where customers have the freedom to self-hostthe software or choose a competing service provider for the same software. Thus, the maincompetitive advantage of an open source service provider is the customer experience they offer,
which may be more convenient, cost-effective, reliable, secure, or performant than self-hosting.
However, the trade-off is that customers must share data with the service provider, which may
introduce privacy concerns for personal or sensitive data.
For security, customers should ensure that the service provider has a robust process for promptly
applying security patches. It’s worth evaluating how the service manages dependencies on otheropen source projects to ensure all the software is up-to-date and secure. The customer should also
assess the provider’s security policies, including how they handle data encryption, access controls,
and incident response.
The transparency of open source software allows for thorough code review by the community,
which can enhance security by identifying and fixing vulnerabilities. So customers should look for

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reviews or audits of the software by reputable third parties or security experts within thecommunity. These audits should confirm that the provider follows secure coding practices andstandards during the development process, and should consider whether the provider uses CI/CD
pipelines with integrated security checks to catch vulnerabilities early.
For privacy, customers should verify that the service collects and stores only the data necessary
for its operation, minimizing the risk of data exposure. The service should encrypt data both intransit and at rest, using strong encryption. Access control mechanisms should ensure that only
authorized personnel can gain access to sensitive data.
The customer should check that the service gives users control over their data, such as the ability
to delete or export it. The service should comply with relevant privacy regulations, such as theEuropean Union’s General Data Protection Regulation (GDPR) and California’s Consumer Privacy
Act (CCPA), and provide transparency about its data handling practices.
It’s important to check that the provider has clear policies and procedures for responding to data
breaches, including notification requirements. The customer should also review the provider’sprivacy policy to understand how data is collected, used, shared, and protected, and consider any
third parties the provider may share data with and ensure they also adhere to strict privacy
standards.
In general, it’s valuable to look at community feedback and reviews to gauge the reputation andtrustworthiness of the software and the service provider. A robust community or organization
should be actively maintaining and supporting the open source project. The customer shouldverify that the provider has regular data backup procedures and robust disaster recovery plans,and check whether the service uses data redundancy to ensure availability and reliability.
Service providers should be aware that customers will be evaluating their security and privacy
practices, community reputation, compliance with regulations, and transparency in handling
data, and consequently should take steps to follow best practices.

Common Agreements Between Service Provider and Customer
Service providers commonly adopt legal terms and agreements that form the legal andoperational backbone of the relationship between the company and their customers. These
agreements help ensure clear communication, set expectations, define responsibilities, andprovide legal protections for both parties.
The Terms of Service (ToS) for a service, also known as Terms and Conditions (T&C) or Terms ofUse, is a legal agreement between a service provider and the customers or users of that service.
The ToS outlines the rules, responsibilities, and limitations that govern the use of the service. It

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protects both the service provider and the customer by clearly defining what each party can andcannot do while providing or using the service. Some common elements of a ToS agreement are
confirmation that the user agrees to comply with its terms, guidelines on acceptable behavior andprohibited activities, details on who owns the content created or uploaded by users, informationon account creation, security, and termination, arbitration or mediation processes for resolving
conflicts, and limits on the service provider’s liability for damages.
A Privacy Policy is a statement that outlines how the service provider collects, uses, stores, andprotects user data. Some common elements of a privacy policy are the types of data the service
provider collects and their collection methods, how they use the data, conditions under which theservice provider may share data with third parties, and information on user rights regarding theirdata, such as access, correction, and deletion.
A Service Level Agreement (SLA) is a formal, documented agreement between a service provider
and a customer that outlines the expected level of service, including the specific performance
metrics, responsibilities, and expectations. The SLA defines the standards for service delivery,
providing a clear framework for measuring and managing service performance. Some common
elements of an SLA include a detailed description of the services provided, specific targets forservice performance such as uptime and response times, methods for measuring and reporting
performance, consequences for failing to meet performance targets, and procedures for reviewing
and updating the SLA.
A Service Level Objective (SLO) is a key component of a Service Level Agreement that specifies
measurable targets or goals for service performance. These objectives quantify the expected levelof service between a service provider and a customer and are used to ensure that the service
consistently meets the agreed-upon standards. Some common elements of SLOs include specificmetrics the service provider will measure to evaluate the service performance (for example,
uptime, response time, resolution time, and throughput) the desired or expected values for eachperformance metric, the techniques and tools used to measure and monitor the performance
metrics, the specific components or aspects of the service that the SLO covers (for example,
hardware, software, network components, or specific processes), and the consequences orrewards based on whether the service meets or fails to meet the SLOs (for example, financial
penalties, service credits, or performance bonuses).
A Data Processing Agreement (DPA) is a contract between a customer (the data controller) and aservice provider (the data processor) involved in processing personal data. The DPA details the
responsibilities and obligations of both parties to ensure compliance with data protection laws,
such as the GDPR. In some jurisdictions, a DPA between a service provider and a customer ismandatory.

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Cost Structures and Investments
The most significant expenses in a service provider business model are the fixed costs related tohosting the services, such as purchasing server hardware, paying for data center space, electricity
to power and cool the servers, network bandwidth, and salaries for deployment and maintenancestaff. Some service providers may also have variable costs for software licenses or third-party
services. Customers who choose to self-host their services bear these costs directly.
By choosing open source software, service providers and customers can reduce or eliminate
licensing costs compared to proprietary software, because by definition open source software
charges no fee for the software license. Employing open source software to build services can also
save on development time and resources, and community-driven maintenance and updates canlower long-term costs. However, it’s important to consider the total cost of ownership (TCO) of theopen source software, including potential support, maintenance, and integration costs.

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Guided Exercises
1. Name some ways that service providers can earn revenue without charging the users of theservice.

2. What are some reasons that a service provider might offer its software for self-hosting by
customers?

3. Why would a service provider release its software under the GNU Affero GPL license?

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Explorational Exercises
1. What is an Acceptable Use Policy (AUP)?

2. What is an End User License Agreement (EULA)?

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SummaryThis lesson discusses service provider business models that rely on open source software, andvarious revenue streams, including subscription, ad revenue, hourly rate, and commission-basedmodels. It highlights the impact of open source software licenses on service providers,emphasizing their benefits and obligations. The considerations of security, privacy, and reliabilityof services, along with the importance of Terms of Service (ToS), the Service Level Agreements(SLA), and the Data Processing Agreement (DPA) are also addressed.

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Answers to Guided Exercises
1. Name some ways that service providers can earn revenue without charging the users of theservice.
The service can offer ads, for which the advertisers pay. The service can charge a commission
to vendors who offer products or services on the site, such as retail or travel. The service
provider can sell customer data, a practice that many customers would object to and thatshould be explained in the Terms of Service.
2. What are some reasons that a service provider might offer its software for self-hosting by
customers?
Potential customers can try out the software to check its features and reliability before signingup with the service provider. Customers might also find bugs and even propose fixes.
◦ Why would a service provider release its software under the GNU Affero GPL license?
The Affero GPL requires other service providers to release any changes they make to thesoftware under the same license. This provision prevents competitors from taking
advantage of the service provider by adding a few enhancements that they keep proprietary
and then promoting their version of the service as superior to the original.

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Answers to Explorational Exercises
1. What is an Acceptable Use Policy (AUP)?
An Acceptable Use Policy (AUP) is a policy that defines acceptable and unacceptable uses of theservice, to prevent abuse and ensure a secure and reliable environment. Some common
elements of an AUP include a description of specific actions that are not allowed, such as
spamming or hacking, obligations of users to use the service responsibly, actions the service
provider may take in case of violations, such as suspending a user’s account, and procedures
for reporting and addressing violations.
2. What is an End User License Agreement (EULA)?
An End User License Agreement (EULA) is a legal contract between a proprietary software
provider and an end-user (not a company or organization), granting the user the right to use
the software under certain conditions. Some common elements of EULAs include the scope andlimitations of the license (for example, personal use or non-transferable license), prohibited
actions (for example, reverse engineering or redistribution), conditions under which thelicense can be terminated, and ownership and protection of intellectual property rights. Fully
open source services substitute an open source software license in place of a proprietary EULA.

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054.3 Compliance and Risk Mitigation
Reference to LPI objectives
Open Source Essentials version 1.0, Exam 050, Objective 054.3
Weight3
Key knowledge areas• Understanding how to ensure license compliance• Understanding how to maintain information about licenses• Understanding the concept of Open Source Program Offices• Understanding the implications of copyright, patents and trademarks on open source
business models• Awareness of legal risks related to open source business models• Awareness of financial risks related to open source business models
Partial list of the used files, terms and utilities• Software Composition Analysis (SCA)• Software Bill Of Materials (SBOM)• Software Package Data Exchange (SPDX)• OWASP CycloneDX• Open Source Program Offices (OSPO)• Product warranty• Product liability• Export regulations
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Lesson 1
Certificate:Open Source Essentials

Version:

1.0

Topic:

054 Open Source Business Models

Objective:

054.3 Compliance and Risk Mitigation

Lesson:1 of 1Introduction
An old quip in open source says that “Free software doesn’t come for free.” While free and open
source software permit great innovation and creativity, users and developers have to comply witha number of rules. This lesson covers compliance and risk in open source software.
The lesson lists basic steps that developers need to comply with licenses, the risks of using open
source software, and ways of tracking and cataloguing the software the organization is using.
We’ll look at how these tasks can be turned into policies and promoted by an Open Source
Program Office (OSPO).

Requirements for Releasing Software Based on Open Source
Components
If the organization uses software internally, free and open source software licenses impose norequirements. The organization might define its own rules to prevent vulnerabilities, make sureeveryone is using the same components, or for other reasons. But that’s beyond the scope of thislesson. Any requirements that the open source licenses or the organization itself impose on the176|

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use of software should be documented, and the organization should provide training in its
policies.
Even if the organization runs software on its web server and offers services with which people
outside the organization interact, most free and open source software licenses impose norequirements. However, the GNU Affero Public License requires adherence to copyleft
requirements for software running as a service too.
The legal requirements of each major free and open source software license have been fully
explored in other lessons, so this section just offers a list of actions that developers and managers
should take to comply:
Vetting open source components
The organization needs clear policies and education around what open source software to use
and where to include it in products. Such policies cover compliance, as well as other issues
such as ensuring security and participating in the community that develops the software.
Keep the original license in the code
Developers must not strip the license from the component they use. Including the license in thesource code is usually a requirement in the license. In fact, removing the license could beconsidered plagiarism, because the developer makes it look as if they wrote the code. Removing
the license could also lead to serious trouble later, because the organization could violate thelicense when the code is included in its products.
Keep track of licenses
The organization must maintain a catalog showing the license of each file or package used by
the organization, in order to make sure it is complying with the licenses.
Acknowledge the author
Nearly all licenses require that credit be given to the copyright owner (often called the“author”) when discussing and promoting the software. Each license explains what to include
in this notice: Typically, they require a standard copyright notice with the year and the name of
the copyright owner. This notice should appear in any documentation related to the productusing the component, including the advertising and web site for the device or program.
Don’t imply endorsement
Some BSD licenses require the person distributing a product with the components to make sure
not to imply that the copyright owner endorses the product. Even if the requirement is notstated, complying with it is the ethical thing to do.

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Offer the source code for copyleft licenses
If an organization distributes a binary file containing copylefted components, whether as asoftware distribution or on a device, the organization has to offer the public the source code tothose components. If the organization changes the code and redistributes the derivative workin binary form, the source code for the changed (derived) version must be offered to the public
as well. Distribution can be done through any means that make access convenient to the public,
such as posting the code on a web site or offering it on a disk or USB stick.
Don’t include copylefted components in proprietary products
If the organization incorporates copylefted components into a product, under somecircumstances the organization has to release the whole product under the same copyleftlicense. The conditions that trigger this requirement vary from license to license. It’s sometimes
unclear, though, what kind of use triggers the copyleft requirement. So, except for clear
situations such as using an open source library (which should not trigger the copyleft’s
reciprocal requirement), developers should be very careful about their use of copyleftedcomponents unless the organization is prepared to release its product under the same license.
Document code changes
When distributing modified versions of code, clearly indicate the changes that the organization
made.
Grant patent rights
Some free or open source software licenses require a grant for patent use on the software.
Thus, if an organization releases code under such a license, and holds a patent on some process
in the code, the organization can’t charge a fee or exert other controls based on its patent toanyone using or adapting the code.
Respect trademarks
Some open source software is covered by trademarks. Trademarks can cover words andphrases, logos and other images, and many other things. On the one hand, an organizationmust handle the trademark properly for any software it uses: A common violation is to parody,
alter, or simply display a trademark without permission. On the other hand, if the organization
wants to use the trademark, it must comply with the trademark owner’s requirements, whichmight rule out modifications to the software.

Risks of Open Source SoftwareThis lesson is about compliance, so we’ll focus on risks in that area, but cover a few other topics
too.

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License Violation
Free and open source software licenses have to be treated as seriously as other licenses andcontracts. Organizations do enforce them, such as the Software Freedom Conservancy, which acts
on behalf of small copylefted projects that don’t have their own enforcement mechanisms.
These organizations usually approach lawsuits as a last resort. Most violations are unintended,
and are easy to resolve with education. Still, it hurts an organization’s reputation to be seen as
ignorant and insensitive toward the communities on whose software it depends.
And lawsuits have actually been launched when a software user is flagrantly refusing tocooperate, and when the software and the defendant are important enough.
Even if an organization is not punished with a lawsuit, the damage that a license violation does to
its relationship with the community, as well as to its reputation, can be substantial. A project canbe derailed by something as simple as having developers' questions go unanswered on the forums
devoted to the software they’re trying to use.
It can be a disaster for someone to find copylefted software in a proprietary product. To comply
with the license, the developers must either strip out all the copylefted code or free their productunder the copyleft license. Making their software free, with source code available, could have direeffects on business models based on license fees or other ways of monopolizing the value of the
product.

Trust and Reputation
We’ve seen that license violations can be very damaging. Other types of behavior that disrupt
trust and reputation also introduce risks.
Some organizations release software under a free or open source software license, and thenannounce at some point that future versions will be under a proprietary license. This switch canbe tempting, because many open source projects fail to receive financial support from enoughclients.
But such license changes induce anger among both clients and the external developers
contributing to the project. Sometimes, external developers take the free version and continue todevelop it independently, a step known as forking the project. The free version might becomecompetitive with the company’s proprietary version and draw customers away from thecompany.
There are also risks when participating in project forums. A company must learn how to be a good
citizen. Common problems include:

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Open Source Essentials (Version 1.0) | Topic 054: Open Source Business Models• Trying to use a company’s financial or code contributions as leverage to force the project in a
direction that other developers don’t want
• Making too many demands on the community, such as by pressuring it with a lot of feature
requests or even too many questions• Being rude in other ways and violating the project’s code of conduct• Trying to dominate publicity or capitalize inappropriately in other ways on the project’s
success

Unrewarded Investments
Business models are discussed in another lesson; this section just notes the financial risk ofparticipating in open source projects.
Companies might start or join open source projects with the expectation of deriving revenue
through some mechanism such as support contracts, SaaS contracts, data collection, or evendonations and grants. Unfortunately, those who conduct open source projects often find them lesslucrative than hoped for. Of course, any business takes a risk when starting a new project, but it’sparticularly hard to find a reliable source of income for open source.
Open source seems most sustainable when it supports some other form of income, such as the saleof hardware devices, cars, printers, etc.

Forks
As we’ve seen, members of a project sometimes disagree on the project’s roadmap, leadership, orother aspects and create an alternative project on the same code base. Forking can also be done by
an organization to create a specialized version of the software. For instance, Android uses a
specialized version of Linux that Google maintains. (Google also makes a lot of contributions tothe core version of Linux, and they are not always accepted.)
Organizations may create a fork for various reasons. They might submit their changes to the core
project and have them rejected, because other developers don’t want them. In a project with apermissive license, or a project used only within the organization, it might want to keep itschanges secret.
The risk of a fork is that the developers of the forked project are responsible for the maintenanceof the entire product. If important bug fixes or new features are added to the core project, thedevelopers of the forked project must duplicate the changes or forego their benefits. As time
passes and the projects get further apart, keeping apace with changes in the core project becomes
harder and harder.

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Incompatible Licenses
As explained in other lessons, some free and open source software licenses have incompatibleclauses. Such components can’t be used together in a product.
This problem is likely to arise during a merger or acquisition. Each company might have beenusing software with a particular license, and if they want to combine the code in their projects,
they must make sure the licenses are compatible.

Product Liability
Many open source software licenses (and the terms of service for many proprietary software andservices, for that matter) explicitly disavow any liability for the software’s use. Another way to say
this is that the license or terms of service offer no warranty or guarantee.
Software vendors are rarely held responsible for problems with their software, but clients
occasionally sue them or try other forms of punishment. Courts don’t have to recognize the “nowarranty” clauses.
Increasingly, laws and regulations are imposing responsibilities on the creators of software. These
legal restrictions — or at least, proposals for restrictions — are seen particularly now for artificial
intelligence, but sometimes are broader.

Export Regulations
Many countries restrict the export of goods and software. In software, such regulations apply
most often to security products, and specifically to the use of cryptography. The United States used
to have strict controls on any software containing cryptography, but the controls have beenrelaxed on open source projects.
Companies should be aware of the export regulations where they are creating software, in casethese regulations affect the sale and distribution of their products.

Software Bill of Materials: Know What You’re Using
Many products come with a bill of materials, which is just a list of all their components. For
instance, when you buy a consumer product, it might include a sheet of paper listing all the parts,
down to the nuts and bolts. The list might include useful information such as the dimensions of apart, and a part number so you can order a new part.
Open source projects are now including a Software Bill of Materials (SBOM, pronounced “Sbomb”). At the very least, an SBOM lists packages, filenames, licenses, authors or owners, andVersion: 2024-07-26|

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version numbers. Many SBOMs go further and include information about security vulnerabilities.
Projects generate an SBOM for each release using automated tools. Users can scan the SBOM tofind information they need. For instance, extracting licenses helps the organization decide quickly
whether the components are compatible with their own code and whether it’s legally permitted touse the components with their code.
Similarly, extracting version information on each package helps the organization discoverwhether different parts of its product depend on different versions of a particular library. Using
two versions of the library causes bloat at the very least. It also could create confusion and errors,
if a component is built with the wrong version.

Standards for SBOMs
Because computing environments use enormous quantities (sometimes tens of thousands) ofcomponents and make frequent changes, SBOMs must be highly structured so that information
can be extracted automatically and quickly. This section describes two of the most popularformats in the open source world:
Software Package Data Exchange (SPDX)
The format represents each package and all the contents of that package in a tree structure.
The format documents dependencies between files, and other relationships. Pointers to
information, known as “snippets,” can be created and then used throughout the document sothat information needs to be defined in only one place. This format was developed by the LinuxFoundation.
CycloneDXThis is a larger format with more detailed fields, particularly for vulnerability information. The
format was created by the Open Worldwide Application Security Project (OWASP) and ispopular in the military and other organizations with a focus on security. For instance, an entry
for a file could include a name for a security vulnerability, the source of information about thevulnerability, affected targets, and more. This format is also designed for cloud deploymentsthat can include thousands of different systems.
Both SPDX and CycloneDX create hierarchical structures in various formats, including JSON and
XML. Many tools exist for each standard, both to create the formats and to scan created files for
information. Popular version control repository sites let developers create an SBOM in one ofthese formats with the click of a button.

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Software Composition Analysis
Knowing what an organization is using requires an assessment of its software that includes anunderstanding of where it comes from, what vulnerabilities it contains, what licenses it uses, andother factors that help an individual or organization decide whether to use the software. This task
is called Software Composition Analysis (SCA), and many tools exist to perform sophisticated scansof SBOMs and of software itself.
Some tools extract license information, which helps an organization decide whether the software
is safe to include in a product and whether different components have compatible licenses. Sometools even compare code snippets to libraries of common open source projects to find out whether
code was taken from the open source projects without proper attribution.
Running these tools is especially crucial during a merger or acquisition. The acquiring company
might find that the software it wants to acquire is less valuable than they had expected, because it
contains open source components that impose requirements interfering with its intended use in
the new organization.

Formal Policies and Compliance
The processes and techniques described in this lesson should be fashioned by managers with
input from developers, attorneys, and other knowledgeable people. This section describes some ofthe policy decisions that organizations need to make concerning open source software. We’ll end
with a description of an Open Source Program Office (OSPO), which can be an advocate andinformation source for the policies.

Principles Governing the Use and Contribution of Open Source Software
Organizations can benefit greatly from using and contributing to open source software, but theyneed to do so in ways that protect their own interests as well as benefit the open source projects.
Policies should be defined for:• Where to use open source software (operations, internal projects, client-facing products, etc.)• What makes an open source project appropriate for the organization: features, performance,
security, roadmap for future extensions, and community viability• Scans for software composition analysis, and where resulting documentation should be stored• Rewards for developers contributing to open source software, including their participation in
public forums• Guidelines for contributing to projects, including how to be a public representative of the

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company• Documentation requirements, so that developers outside the core team can understand how tocontribute and interact
The OSPO can coordinate the creation of these policies and education to ensure compliance.

Contributor Agreements
Open source projects need to ensure that contributions are legitimate: for instance, that the code
has not been taken from some proprietary product or an open source project with anincompatible license. Many open source projects require developers to provide a document calleda Contributor License Agreement (CLA) to ensure the legitimacy of their contribution.
Developers at an organization who contribute to these projects might ask the organization’s
lawyers to review and approve the CLA. Thus, the lawyers should understand the relevance of theclauses of CLAs and be prepared to vet them.
Numerous criticisms have been aired about CLAs, including their complexity and the loopholes
they leave for projects to use contributed code in ways not desired by the contributors.
Many projects, instead of a CLA, ask a developer to sign a short document called a Developer
Certificate of Origin (DCO), attesting that the developer has a right to contribute the code. The DCO,
which is discussed in another lesson, generally is not submitted to a lawyer for review.
Some projects simply ask contributors to sign the copyright to their code over to the project in a
Copyright Assignment Agreement (CAA). However, many contributors dislike this practice, because
they can’t use the code in some proprietary project of their own and because it grants a lot of
power to the project.

The Open Source Program Office (OSPO)Open source projects combine unusual social, technical, legal, and organizational factors. At thistime, knowledge of these factors has not swept through organizations to the point where all
managers, developers, attorneys, and others understand them deeply. So organizations canbenefit greatly from creating an Open Source Program Office (OSPO) as a central point for
advocacy, policy-making, policy enforcement, and education.
As a kind of all-purpose department, OSPOs can perform many roles, such as:
Promoting open source
OSPOs can disseminate both the concepts behind the open source movement and suggestions

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for using open source throughout their organization. They can remind developers to look foropen source solutions to the problems they’re solving and encourage them to adopt
appropriate software. They can urge managers to grant time to developers to participate inopen source projects, and to recognize that participation when evaluating developers for salaryraises and job promotions.
Policy definition
OSPOs can mobilize managers to create policies and set up repositories for them.
Policy enforcement
OSPOs can remind developers to scan software and SBOMs and to follow corporate rules about
the use of open source. The OSPOs can preserve documentation about the software adopted,
and other aspects of corporate use.
Education
OSPOs can explain to developers how to evaluate and participate in open source projects,
explain to lawyers the details of licenses and other legal considerations, and help the company
understand the organizational and cultural changes that facilitate the use of open source
software.
There are numerous documents and online resources for creating an OSPO. A small organization
can farm out the task to a third party who is expert in that area.

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Guided Exercises
1. Why shouldn’t a developer just take code they like from an open source project and put it into
their own code without preserving the license?

2. What sorts of documents would a developer sign when making a contribution to an open
source project?

3. You find some open source software that would make an excellent basis for your retail site. Can
you overlay your logo over its popular logo to make an eye-catching image for your web site?

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Explorational Exercises
1. What considerations might lead you to make a fork of an open source project for your own use,
despite the drawbacks of forks?

2. When you find some open source software that meets your need, what are some reasons you
might reject it?

3. You’d like to use a copylefted logging tool in your proprietary product. Is there a way to
combine them that doesn’t require you to offer your product under the copyleft license?

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SummaryThis lesson has covered many considerations to take into account before using free and open
source software. It explained how to adhere to licenses, various legal, reputational, and financial
risks, and how to define important policies and enforce them within your organization.

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Answers to Guided Exercises
1. Why shouldn’t a developer just take code they like from an open source project and put it into
their own code without preserving the license?
This is usually a violation of the open source license, and also represents plagiarism andcopyright infringement. Practically speaking, the organization can be forced to comply with thelicense, with consequences ranging from embarrassment and reputational damage to thedestruction of their business model if copylefted code is mixed in with proprietary code.
2. What sorts of documents would a developer sign when making a contribution to an open
source project?
A Contributor License Agreement is a legal document granting rights to the open source
organization to use the code. A Developer Certificate of Origin is a shorter and simpler
document promising that the developer has a right to contribute the code. A CopyrightAssignment Agreement grants all rights to the receiving organization.
3. You find some software that would make an excellent basis for your retail site. Can you overlay
your logo over its popular logo to make an eye-catching image for your web site?
If the project has trademarked its logo, your change would probably violate the trademark.
Even if the logo is not trademarked, your change could be seen as disrespectful as well as
confusing.

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Answers to Explorational Exercises
1. What considerations might lead you to make a fork of an open source project for your own use,
despite the drawbacks of forks?
If you are satisfied with the current state of the code, you might not need to keep up withchanges to the core project. You might want to create a product substantially different from theuses to which the core project is put, and therefore be willing to part ways with the core
project. The code might be valuable enough in your business plan that your team is willing totake on complete responsibility for its development and maintenance.
2. When you find some open source software that meets your need, what are some reasons you
might reject it?
The code might contain too many bugs and security vulnerabilities, the project’s developer
community might not function well, you might not like the direction in which the code isevolving, or the license might not be compatible with other code in your product.
3. You’d like to use a copylefted logging tool in your proprietary product. Is there a way to
combine them that doesn’t require you to offer your product under the copyleft license?
Integrating the code for the tool into your code might trigger the copyleft’s reciprocal
requirement, depending on which license is in effect. The logging tool must be separated fromyour product so that your product is not seen as derivative. For instance, it might be safe to run
the copylefted tool as a separate process and communicate with it through message passing.

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Reference to LPI objectives
Open Source Essentials version 1.0, Exam 050, Objective 055.1
Weight3
Key knowledge areas• Understanding the relevance and goals of project management in software development• Basic understanding of waterfall software development• Basic understanding of agile software development, including Scrum and Kanban• Understanding the concept of DevOps
Partial list of the used files, terms and utilities• Phases in waterfall projects (requirement engineering, business analysis, software design,development, testing, operations)• Roles in waterfall projects (project managers, business analysts, software architects,
developers, testers)• Organization of Scrum projects (sprints and sprint planning, product and sprint backlog,
daily scrums, sprint review and sprint retrospective)• Roles in Scrum projects (product owners, developers, scrum masters)• Organization of Kanban projects (Kanban boards)

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Lesson 1
Certificate:Open Source Essentials

Version:

1.0

Topic:

055 Project Management

Objective:

055.1 Software Development Models

Lesson:1 of 1Introduction
Life is full of projects. A project might be planning a movie night, a trip, or a family event,scheduling the children’s week, or improving your work on a hobby. It does not matter what you
want to carry out: You need to make plans and take actions. We usually create several scenarios,with plan B, plan C, etc. This is no different in the world of software development.

Roles in Software Development
A variety of skills are needed for successful project management, so it’s useful to find different
people to fill well-defined roles. The following sections lay out some of the roles commonly foundon software projects.

Project Manager
Managing a project is a highly complex task. Some situations look easy at first — but it takes careand experience to get them right. The person doing this is the project manager.
Project manager responsibilities include ensuring that the project is finished on time, within

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budget, and with acceptable quality. Even if they don’t write a single line of code, project
managers are the ones who are responsible and accountable for the team’s results. They have toalign with clients about deadlines. They also talk to the people in other roles to make sureeverything is in order.

Business Analyst and Requirement Engineer
There is no place for micromanagement — at least not in a healthy workplace. Business analysts(BA) and requirement engineers (RE), internal or external to the project team, are the right handsof the project managers. They are responsible for creating rich and clear documentation about therequirements. They are also the bridge between the clients and the developers. The clients
communicate through plain language, which the BA/RE ensures will provide clear andunequivocal documentation with which developers can effectively do their work.
Imagine you are being asked to bring a “big cake” to a party. What does “big” mean? Ten slices ortwenty? Maybe it’s the cake for a big wedding and it should be one hundred slices. The BA/RE has
to specify requirements such as quantities exactly, so that the developers will know, say, that an
application is designed for a specific number of users.
We are just at the beginning of defining requirements, but you already can see the importance ofclear communication. Communication is essential for any joint work, but is perhaps even more
important on an open source project, as people with very different backgrounds might work oneach part of the project. Someone may collaborate as a student, someone else as a parent, a person
who is retired or between jobs, etc. Even so, progress has to be smooth in this environment — socommunication can’t hold up progress.

Developers, Architects, and Testers
To implement the requirements, a software project needs developers who are creating the productbased on the documentations and design decisions. Their work is judged by the architect, whousually has the most extensive technical and domain knowledge of anyone on the project. Everydeveloper, especially the senior ones, is responsible for their own code, but big decisions are madeor approved by the architect.
Sometimes people are specifically designated as testers, who are responsible for all kinds oftesting, documenting the results, and creating issue tickets.

Planning and Scheduling
Now that we have discussed basic roles, let’s talk about the phases of a project: planning,scheduling, implementing, maintaining/testing, and delivering. Some phases differ in various

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software development models, but planning and scheduling are general topics we’ll discuss before
diving deeper into different models.
Planning takes place after the BAs/REs provide the list of requirements. Planning consists of one ormore meetings about what the team wants to achieve, how they plan to accomplish it, and how
long it would take. Usually, some risk analysis takes place at these meetings as well.
Planners then have to schedule the work and create milestones. At each milestone, the team knowsthat one big, important part is done. Long-term components or features can take months, soplanners have to factor in vacations, holidays, and — especially during cold seasons — some sicktime off, to ensure an accurate delivery time and to avoid rush and panic approaching thedeadline. Under a good schedule, the developers feel more relaxed and can deliver high-quality
solutions in time, without breakdowns.

Common Tools
Two tools that benefit all models, and project management in general, are a version control system(VCS) and an application lifecycle management (ALM) platform. Version control is discussed in
depth in another lesson, so let’s say a few words about ALMs.
ALM is a comprehensive framework that manages the lifecycle of a software application frominitial development through maintenance and eventual retirement. ALM integrates people,
processes, and tools to enhance collaboration and efficiency, ensuring that all stages of thesoftware lifecycle are well-coordinated and aligned with business goals. This approach helps tomaintain the quality, performance, and reliability of applications throughout their lifespan.
Now that we have a general overview of roles and lifecycle phases, let’s dive into models.

Waterfall Model
This is one of the earliest and most straightforward methodologies in software development. You
can imagine it as a staircase, where each step needs to be finished before moving forward. But themodel goes in only one direction, making it suitable for projects with clear requirements andminimal or no expected changes.
Although the simplicity of this model can be an advantage, the rigid menthodology can be a
drawback when flexibility and adaptibility are necessary. And these days, usually, everythingchanges while you’re working on your project.
As previous sections explained, to start development, a project needs to have the requirements, afinished plan, and a finalized schedule for the work with milestones. In the waterfall model, these

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are the outcome of requirement engineering and business analysis.

Requirement Engineering
In this initial phase, all the project requirements are gathered and documented. This work
involves extensive discussions between the project manager and stakeholders to understand theirneeds and expectations. The outcome is a comprehensive requirements specification documentthat outlines what the system should do.

Business Analysis
Business analysts examine the requirements from a business perspective to ensure they alignwith organizational goals. BAs perform feasibility studies, risk assessments, and cost-benefit
analyses to determine whether the project is viable and worthwhile. The insights gained are used
to refine the project scope and objectives.

Software Design
Software design is the step where the architect creates a detailed design specification for thedevelopers to follow. Given this specification, the team can start to implement therequirements — in other words, start the developement phase, which comes next.

Development
The development phase is where the magic happens — where the code is written. Following the
documentation and the design decisions assiduously, the developers write their parts. Afterdevelopers review their code with other developers or the architect, this phase can be considered
done.

Testing
Development is followed by a phase of testing, managed by the testers. There are different types oftesting, described in another lesson, such as unit testing, integration testing, system testing, andacceptance testing.
The goal of these tests is to bring issues to the surface before release, and to allow the developers
to fix them in time — not after the project is deployed and published and users can be irritated
and frustrated by bugs.

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Operations
After the tests are passed and bugs are fixed, the project can be released — that is, deployed to the
production environment. This phase can contain installation, configuration, and sometimes evenuser training. After the project is ready to use, it is in a maintenance phase, where the team canhandle issues from the users and deliver updates if necessary.

Evaluating the Waterfall Model
What have you noticed while reading about this model? Do you find it efficient? Is something
missing? Let’s see the pros and cons.
The waterfall model benefits from:
Clear structure
The linear process makes it easy to manage, understand, and follow.
Meticulous documentation
Detailed and thorough documentation at each phase helps the team understand what’s needed
during development and future maintenance.
Predictability
Clear, defined milestones help to provide a foreseeable timeline and budget.
Simplier project management
Thanks to its linear and straightforward flow, the model is easy to manage.
The waterfall model suffers from:
Rigidity
The linear inflexibility of the model makes it difficult to implement any changes after therequirements phase is finished.
Late testing
During the development phase, testing is haphazard or missing, which can lead to laterecognition of important issues.
Assumption of perfect requirements
The model requires and assumes that every requirement is correct and clear, which can bevery unrealistic. The model does not make room for checking during development to makesure the requirements are accurate and are understood by developers.

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Lack of feedback
Only in the last phase can a customer say anything about the product. So if something (or a lotof things) do not meet their expectations, the problem turns up only at the very end.

Agile Software Development, Scrum, and Kanban
To explore this set of more modern software development models, let’s start with the word agile:
What does it mean? Agility expresses the ability to react and move quickly, in both the physicaland mental world. The goal is the same in software development.
Agile software development is a methodology that builds on iterative development, flexibility, andcollaboration. It focuses on delivering small improvements while always gathering feedback andimplementing it during development. This approach allows quick reactions, adjustments, andresponses, saving time and ensuring that the project meets users' and clients' expectations.
The agile movement was launched in 2001 by an online Manifesto for Agile Software Developmentthat listed its principles as follows:
We are uncovering better ways of developing software by doing it and helping others do it.
Through this work we have come to value:• Individuals and interactions over processes and tools• Working software over comprehensive documentation• Customer collaboration over contract negotiation• Responding to change over following a plan
That is, while there is value in the items on the right, we value the items on the left more.
— Manifesto for Agile Software Development

Scrum
Scrum is one of most popular frameworks — maybe the most popular — within agile softwaredevelopment. Scrum is built upon the following building blocks:
In a nutshell, Scrum requires a Scrum Master to foster an environment where:
1. A Product Owner orders the work for a complex problem into a Product Backlog.
2. The Scrum Team turns a selection of the work into an Increment of value during a Sprint.

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3. The Scrum Team and its stakeholders inspect the results and adjust for the next Sprint.
4. Repeat— The 2020 Scrum Guide

But who is the scrum master and product owner? What is a product backlog and a sprint? Let’s
dive into the roles and processes.
Sprints and Sprint PlanningA sprint is a development phase typically lasting two to four weeks, during which some previously
agreed tasks and/or features are completed. To get agreement on tasks, sprint planning comes in.
This process is where the team makes decisions about which tasks can be completed during theupcoming sprint.
These choices are based on the priorities set by the product owner (PO), who controls the projectand often provides the funding for it.
Product Backlog and Sprint Backlog
As just explained, the PO manages the list of priorities, which contains all the desired work on the
project. In Scrum, this list is called the product backlog. Each sprint backlog contains the selectedtasks for the current sprint from the product backlog. The sprint backlog contains the elementsthat were chosen by the team during sprint planning.
Daily Scrum or Stand-up
The daily Scrum or stand-up meetings are short, efficient meetings where the teams discuss theirprogress, highlight issues and blockers, and share their plans for the day. A scrum is usually heldat the very beginning of the workday.
Increment
An increment is a goal achieved during a sprint. Each sprint should result in one or moreincrements. The correctness of the task or features achieved by the increment should be verified
by testing.
Sprint Review
The sprint review is a meeting to inspect the sprint’s outcome. These meetings are usually morethan demos — the goal is to get feedback based on the Scrum team’s results. As the aim is to reachthe product goal, the stakeholders give opinions and suggestions about future adaptations. The

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outcome of these meetings can be changes or additions to the product backlog.
Sprint Retrospective
The goal of the sprint retrospective is to enhance quality and effectiveness — and not just in thecurrent product. The retrospective should reveal hidden tensions within the team, any lack of
information that slows down processes, outside dependencies that should be eased to lighten theburden of the team, etc. The team discusses what went well, what problems they faced, and what
solutions were (or were not) found for those issues.
The outcome is a list of problems paired with possible solutions assigned to the responsible
person.
Scrum MasterAll of these meetings are hosted by the Scrum master. Each Scrum team needs one. They are
responsible for facilitating Scrum processes and helping the team keep moving toward the
product goal while issues are encountered during sprints. The Scrum master not only guides
processes, but acts as a coach to ensure effective communication within the team.
Product Owner
The product owner is responsible for maximizing the value of the product created by the Scrum
team. This role may vary across different organizations and teams. Even when delegating tasks,
the product owner remains accountable for the outcomes.
Success requires organizational respect for the product owner’s decisions, which are reflected in
the product backlog and the sprint review’s increment. The product owner is a single person,
representing various stakeholders' needs in the product backlog. Anyone wishing to change thebacklog must persuade the product owner to do so. The product owner defines and prioritizes the
product vision and backlog and ensures the transparency, visibility, and understandability of the
product backlog.
The Scrum master and product owner collaborate to drive project success. Their partnershiphelps the development team deliver high-value features efficiently and effectively.
Developers
The developers implement the requirements following the agreed sprint backlog. They can work
independently, but there are several occasions where they might collaborate: for example, pair
programming or reviewing another developer’s code.

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Evaluating the Scrum Model
Scrum has become favored among software teams, but it too has pros and cons.
The Scrum Model benefits from:
Flexibility
Processes are flexible and iterative, allowing for changes based on feedback.
Customer involvement
Regular feedback from stakeholders ensures alignment with customer needs.
Improved quality
Frequent testing and reviews improve product quality.
Team collaboration
The model emphasizes teamwork and communication through daily stand-ups and regularmeetings.
The Scrum Model suffers from:
Required discipline
Scrum calls for strict adherence to its practices, which can be challenging.
Scope creep
There is a risk that more and more customer requests will be added and hold up the release, if
the product backlog is not managed well.
Role confusion
Standard roles such as Scrum master and product owner can be misunderstood or poorly
implemented.
Resource intensivity
Daily meetings and frequent reviews can be time-consuming.

KanbanKanban is another popular agile framework that emphasizes work visualization, flow
management, and process improvements. One of the big differences between Scrum and Kanban
is that Kanban does not require fixed-length iterations. Thus, it makes continuous delivery more
flexible and can balance different work priorities.

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We’ll look at what teams need for a Kanban project in the following subsections.
Kanban Boards
A Kanban board is a visual tool that tracks the work’s flow through stages. The main and mostimportant columns are “To Do,” “In Progress,” and “Done.” More columns can be added, but thesethree main columns have to be on the board. This visualization helps teams to catch bottlenecks
and see the status of tasks in the blink of an eye.
Work in Progress Limit
A work in progress (WIP) limit helps to avoid multitasking and improves focus. With this limit inplace, there is a point where no more tasks can be added to the “In Progress” column. In this way,
the developers will not be overloaded by tasks and they can focus on the tasks on which they are
currently working.
Team Members
Team members are responsible for completing tasks and establishing a smooth flow through the
Kanban system. They collaborate to prioritize work and highlight and address any kind of issues
that emerge.
Kanban Manager
The Kanban manager oversees the Kanban process, ensuring that the team follows Kanban
principles and practices. This manager facilitates meetings, monitors workflows, and helps
resolve any problem that may arise.
Evaluating the Kanban Model
The core of this model is simple. Let’s look at pros and cons.
The Kanban Model benefits from:
Visual workflow
Kanban boards provide clear visibility of work status and progress.
Flexibility
Lacking fixed iterations, the model supports continuous delivery with substantial adaptability.
Limits on tasks
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focus and efficiency.
Continuous improvement
The model encourages regular evaluation and process improvements.
The Kanban Model suffers from:
Lack of timeframes
Without set deadlines, time management is challenging.
Less structure
The model might lack the structure some teams need to stay organized.
Required discipline
Effective WIP limits and board management require careful attention.
Potential oversimplification
The task descriptions might oversimplify complex projects if not implemented thoughtfully.

DevOpsDevOps is a software development approach that integrates the development (Dev) and operations(Ops) teams to enhance collaboration, efficiency, and the speed of delivery. The primary goal of
DevOps is to shorten the software development lifecycle and provide continuous delivery withhigh software quality. DevOps emphasizes automation, continuous integration and continuous
delivery (CI/CD), and close collaboration between traditionally siloed teams.
Automation is crucial in DevOps for tasks such as code integration, testing, deployment, andinfrastructure management. Automating repetitive tasks reduces errors, speeds up processes, andallows teams to focus on more strategic work.
Continuous monitoring and logging are essential to maintain system health and performance.
DevOps practices include setting up comprehensive monitoring and logging systems to detectissues, analyze trends, and improve system reliability.

Evaluating the DevOps Model
Although DevOps is highly recommended for many types of modern software projects, pros andcons still have to be considered.
The DevOps Model benefits from:

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Speed and efficiency
The model accelerates development and deployment cycles through automation.
Improved collaboration
The model bridges the gap between development and operations teams.
Continuous delivery
The model ensures that software is always in a deployable state, leading to more frequent
releases.
High reliability
Automated testing and monitoring enhance reliability and reduce errors.
The DevOps Model suffers from:
Cultural shift
The model requires a significant cultural change and buy-in across the organization.
Complexity
Managing CI/CD pipelines and automated infrastructure can be complex.
Security risks
Continuous deployment can introduce security vulnerabilities if not managed carefully.
Tool overload
DevOps can be overwhelming due to the multitude of tools and technologies involved.

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Guided Exercises
1. What does agility mean?

2. What is the Scrum definition, according to the Scrum Guide?

3. Why can Scrum perform better than the waterfall model regarding client feedback?

4. What are the positive aspects of DevOps?

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Explorational Exercises
1. Why is the waterfall model not the best to use in a fast-changing environment?

2. What can happen when the role of the Scrum master is poorly implemented?

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Summary
The relevance of project management in software development, especially in open source
projects, lies in its ability to provide structure, enhance communication, define roles, manage
risks, and ensure quality. These elements are crucial for the successful completion of projects andfor fostering a collaborative and productive development environment.
In this lesson, we went through the waterfall model, agile methodologies, and DevOps. Knowledgeof these models is essential to understand project management in software development. There isno golden right way to work — every project is different. In this lesson, you learned the roles,
processes, and pros and cons of various approaches, which can help you in the future tounderstand and perhaps choose the right model for a project.

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Answers to Guided Exercises
1. What does agility mean?
Agility expresses the ability to react and move quickly, in both the physical and mental world.
2. What is the Scrum definition, according to the Scrum Guide?
◦ A Product Owner orders the work for a complex problem into a Product Backlog.
◦ The Scrum Team turns a selection of the work into an Increment of value during a Sprint.
◦ The Scrum Team and its stakeholders inspect the results and adjust for the next Sprint.
◦ Repeat
3. Why can Scrum perform better than the waterfall model regarding client feedback?
Because feedback is collected during development, the final product can better meet client
expectations.
4. What are the positive aspects of DevOps?
Speed and efficiency — Improved collaboration — Continuous delivery — High reliability

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Answers to Explorational Exercises
1. Why is the waterfall model not the best to use in a fast-changing environment?
The waterfall model collects feedback only at the end of development. Thus, any requirementthat was misunderstood by the developers has to be corrected at the very end. If theenvironment changes very quickly, this model should not be used because there is no provision
for feedback in the middle of the development cycle.
2. What can happen when the role of the Scrum master is poorly implemented?
A poorly implemented Scrum master role can hinder the team’s ability to deliver high-quality
products efficiently and can undermine the benefits of adopting Scrum. The team may lackproper guidance on Scrum practices and principles, leading to inconsistent or incorrect
application of the framework.
Without an effective Scrum master to remove obstacles, impediments can slow down progressand reduce team productivity. Miscommunication between team members and stakeholders
can occur, resulting in misunderstandings and misaligned expectations. The team may
experience decreased morale and motivation due to unresolved issues, lack of support, andineffective facilitation of Scrum events. Inefficiencies may arise from poorly conducted
meetings, lack of focus, and ineffective sprint planning and reviews.

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Reference to LPI objectives
Open Source Essentials version 1.0, Exam 050, Objective 055.2
Weight2
Key knowledge areas• Understanding common release types• Understanding software versioning and reasons for major or minor releases• Understanding the lifecycle of a software product, from its planning, development andrelease to its retirement• Understanding the documentation for product versions
Partial list of the used files, terms and utilities• Alpha and beta versions• Release candidates• Feature freeze• Major and minor releases• Semantic versioning• Roadmaps and milestones• Changelogs• Long Term Support (LTS)• End of Life (EOL)• Backward compatibility
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Lesson 1
Certificate:Open Source Essentials

Version:

1.0

Topic:

055 Project Management

Objective:

055.2 Product Management / Release
Management

Lesson:1 of 1Introduction
Most software evolves in many ways over time. In fact, that’s one of the wonderful things about
software: It’s easy to change and requires just a network transfer to update everyone who’s using
the product. So developers add new features, fix bugs and security flaws, port the software to new
hardware, and add interfaces to popular programs and services. As the software changes, newversions or revisions are released.
This lesson covers the logistics for planning and making changes to software, how teams juggle
multiple versions, conventions for naming the versions, and other organizational aspects ofdevelopment that are a subset of the actvities involved in project management. The logistics that
apply specifically to the timing, naming, and control of releases is known as release management.

Characteristics of Releases
Releases vary in terms of stability, backward compatibility, and support. We’ll examine each of
those concepts in the following sections.

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Stable and Unstable Releases
Stability is a key trait users expect from software. The first question many ask, upon hearing of a
new release, is “How stable is it?” In other words, will it work reliably, or will it crash, corrupt
data, or produce incorrect results?
Stability can be measured on a spectrum, and many people are happy to use software even when
there are still some bugs. But development teams tend to keep things simple, and talk in binary
fashion about stable and unstable releases.
Stability refers both to the bugginess of the software and its likelihood to change in ways visible tooutsiders. Developers might consider a release of a software library unstable because they havechanged the functions that programmers call (that is, because programmers might have to rewrite
their software for the next release). Or software might be unstable from a user’s point of view
because developers have removed a feature.
Is there any reason to release an unstable version? Yes: They are valuable for letting users try out
new features early in the project and test for bugs.
Most projects release very early revisions of software for key clients to try out; these are calledalpha releases. No one should use these releases for real work — they are only for testing. In fact,
testers should run alpha releases on computers that aren’t doing any important work, because
bugs in those releases could actually damage data stored on the computer.
When the software is close to being considered stable, the project usually release another test
revision called a beta release. These should still not be used for production work, only for testing.
For both alpha and beta releases, the developers have a process for reporting bugs and tracking
the progress toward fixing bugs.
Some projects include another stage between the beta and stable releases, when developers have
fixed all the bugs they can and think that the product is done. They call the version a releasecandidate and show it to key customers or stakeholders so that these stakeholders can plan how to
use new features.
Finally, some projects put in features that are not quite stable, because important users haverequested them. The developers intend for users to try these features and say whether they like
them, before developers finalize the interfaces and invest the effort to stabilize the features.

Backward Compatibility
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functions that existed in older versions. Compatibility can exist on several levels. For instance, if
the developers maintain backward compatibility for the application programming interface (API),
they promise that old source code can continue to work, but it might have to be recompiled. If
hardware vendors or operating system developers maintain backward compatibility for theapplication binary interface (ABI), they promise that in addition, old executable files can run on
new versions of the hardware.
We’ll look later at the ways projects handle a lack of backward compatibility, when they decidethat the old interface really doesn’t work for the new features or environments they need tosupport.

Support and End of Life (EOL)
Software would ideally get better and better as developers discover and fix its problems. But overtime, features can stop working because of changes in the software’s environment. Also, new bugs
are discovered that were hidden before.
New versions often combine security and bug fixes with new features. You might not want the
new features (in fact, you might prefer some old feature that the developers removed in order tomake way for new ones), but people usually upgrade to the new version to get the security fixes
that will protect them against malicious attacks.
Some people actually keep using old versions of software, refusing to upgrade. This is normallybecause the new version breaks something that was working in their environment. When
companies charge money for upgrades, some customers refuse to upgrade because they don’t
want to pay the extra money, but paying for upgrades is rare in open source.
Developers accommodate the users of old versions, if possible, by fixing bugs in the old versions
without adding the features that break the software. Naturally, the developers can’t do thisforever because it drains time and energy from new work. There will come a time when theyrefuse to fix an old version and tell the users either to upgrade or to make their own fixes.
Fixing bugs and security flaws is called support for the software. This is different from the support
offered by helpdesks and other people who guide users in understanding the software. So far as
release management goes, a supported release is one where the developers promise to fix bugs,
whereas an unsupported release is one where they do not.
Note that the notion of “support” applies mostly to software created by companies or largeorganizations. Smaller open source projects, depending heavily on volunteers, often promise justto do the best they can to fix bugs and put out new versions. They don’t see a need to fix old
versions. Because the code is open source, users who don’t want to upgrade can pay someone tofix an old version.
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When support is in place, developers publish a schedule indicating how long they’ll support eachversion. The date where support ends is called the software’s end of life (EOL). Users can keep theold version up to EOL and expect bugs to be fixed, but after EOL they have to upgrade or taketheir chances.
Major projects, such as the Debian distribution of GNU/Linux, offer long term support (LTS)
versions. That simply means that the developers will keep fixing bugs for a certain number ofyears. Customers who value stability highly might be afraid to install versions of software thathave lots of changes, in case the changes break processes that the customers rely on. Suchcustomers, notably large institutions, like the security of LTS versions.

Software Versioning: Major, Minor, and Patches
We’ve seen that versioning is complicated: Some versions fix bugs, while others add features, andthe versions can vary in stability. Developers try to indicate through labels how big a change tothe software is in each version. The conventions adopted by nearly all projects for labelingversions are called semantic versioning.
Let’s take the early history of the Linux kernel as an example. Linus Torvalds labeled the firststable release 1.0. As he improved the kernel, he labeled subsequent versions 1.1, 1.2, and so forth.
The initial 1 was the major version and the numbers after the period denoted the minor version.
You could assume that version 1.2 had more features and offered more than version 1.1 did.
But there were also innumerable small releases, sometimes just to fix a few bugs. To show that thechanges had a minor impact on the use of the kernel, Torvalds included a third number called thepatch. Thus, 1.0 was upgraded to 1.0.1, then 1.0.2, and so on.
Patch numbers start over at 0 when a new minor version is released, and minor version numbers
start at 0 when a new major version is released.
Developers lump together versions using an “x” to indicate that they’re talking about multiple
versions, such as 1.x for all versions under major version 1.
But what’s the difference between a change that leads to a new minor version and a change thatdeserves to trigger a new major version? Usually, years pass before a new major version isreleased, and it has to reflect a very significant upgrade.
Generally, developers try to keep backward compatibility as versions change. If backward
compatibility cannot be preserved, developers should increment the major version.
Sometimes you see a version number less than zero, usually 0.9. The leading zero indicates an
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guarantee of backward compatibility until the developers release versions starting with 1.
Alpha versions are usually indicated by appending “a” or “alpha” after a release number, such as
3.6alpha. Similarly, beta versions append “b” or “beta” after the release number.

The Software Product Lifecycle
Don’t think the life of a developer is easy. Everybody wants something from them. I want this bugin screen layout fixed A.S.A.P., whereas someone else says that the bug in filenaming takes
precedent. Users clamor for new features, and when different developers work on different
features in parallel, they find that one’s changes may trample those made by another.
Project management, and the subset of these tasks called release management, deal with theseissues. Usually, a senior project member takes on responsibility for this management job.
Like people, software versions go through a lifecycle. Each one begins with a discussion of newfeatures and other changes needed, goes through development and test phases, and is rolled out
in a planned manner.

Planning and Roadmaps
Developers try to lay out, far in advance, what changes they want to make to a product. In
commercial firms, they talk to marketing people, who filter and summarize what their customers
tell them. Open source projects depend more on ideas submitted by developers and users, which
are captured in a database called an issue tracker. If you need a bug fixed or want a new feature,
you fill out an issue. Developers then prioritize the changes and decide who will handle each one.
So how are changes chosen and prioritized? It can be a messy process. But good project managers
on open source projects encourage broad input while ensuring that decisions get made. Some
projects even hold conferences where participants hash out the priorities.
A published roadmap lays out the resulting plans for enhancements and changes. It may extend
many releases and many years into the future. Each step is called a milestone, and might or might
not be associated with a target date.

Release Scheduling
There are two basic ways to schedule releases: time-driven and feature-driven. A project canpromise a release at regular intervals — every six months, for instance — and include whatever isfinished at that point. Alternatively, the project can promise to include certain features in a
release, and let the developers take as long as they need to finish those features.

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As the time for the release approaches, the release manager determines dates for the alpha, beta,
and stable releases. Team members regularly review bug reports and try to plan their work sothat they meet these milestones.
In order to finish a release, a project has to stop accepting ideas for new features and focus on
making the existing features work right. This moment is called a feature freeze.

Documentation for Product Versions
Roadmaps, as mentioned earlier, explain the features that developers plan to include in eachrelease. The release is accompanied by a list of changes called a changelog. Generally, thechangelog lists new features, changes to existing features, features that were removed, featuresthat the developers intend to remove in the future (known as deprecated features), and bug fixes.
Thus, changelogs can get quite long and detailed. Users need to pay special attention to featuresthat were removed or are deprecated, because the users might have to change their programs or
way of using the product. Obviously, developers try to remove only those features that nobody
needs any more.
Each release should change product documentation to match changes in the product. This task
can be time-consuming, and it’s easy for developers to miss a change or lag at producing
documentation.

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Guided Exercises
1. What distinguishes a stable release from an unstable one?

2. Would you expect a feature change between a release named 2.6.14 and a release named
2.6.15?

3. Would you expect a feature change between a release named 2.6.0beta and a release named
2.6.0?

4. Why would you expect release 1.0 not to be backwardly compatible with release 0.9?

5. If you discover a security flaw in a version after a feature freeze but before its release, can you
get the flaw fixed?

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Explorational Exercises
1. Suppose you want to keep using a version of open source software after EOL, because it has afeature you need. What can you do to keep it usable?

2. What are some criteria that allow one bug fix or feature request to be chosen over others?

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SummaryThis lesson described the main characteristics that distinguish releases: stability, backward
compatibility, and support. We discussed the meaning of version names and numbers, and key
aspects of release management, including documentation.

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Answers to Guided Exercises
1. What distinguishes a stable release from an unstable one?
Releases are considered stable in two ways: They work well without crashing or producing
incorrect results, and the interface presented to users or programmers is expected to be
backward compatible with previous versions.
2. Would you expect a feature change between a release named 2.6.14 and a release named
2.6.15?
No. The third number in semantic versioning indicates a patch, which was made to fix a bug or
carry out some other minor task such as reformatting. A feature change should lead to a minor
or major release.
3. Would you expect a feature change between a release named 2.6.0beta and a release named
2.6.0?
No. The beta version is a test version that contains all the features to be included in the final
release.
4. Why would you expect release 1.0 not to be backwardly compatible with release 0.9?
The number 0.9 explicitly warns potential users that the software is still being designed andcould very likely have a different interface when it is stabilized as version 1.0.
5. If you discover a security flaw in a version after a feature freeze but before its release, can you
get the flaw fixed?
Most certainly. The period between a feature freeze and the release is meant as a time todiscover and fix flaws, including security flaws.

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Answers to Explorational Exercises
1. Suppose you want to keep using a version of open source software after EOL, because it has afeature you need. What can you do to keep it usable?
After EOL, the project developers have no commitment to fix bugs, including security flaws.
Therefore, you should follow the project’s bug tracker and mailing lists assiduously to find out
what bugs turn up. Because the code is available, you can and should fix bugs that are in yourversion. In theory, you could even incorporate new features into your version. That would
effectively make your version a fork of the original.
2. What are some criteria that allow one bug fix or feature request to be chosen over others?
For bug fixes, criteria include severity (which is assigned to the bug after it enters the bugtracker) and the number of users affected by it. For a feature, criteria include the number ofusers who want the feature, the difficulty of coding it, and its potential impact on other parts ofthe program.

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Reference to LPI objectives
Open Source Essentials version 1.0, Exam 050, Objective 055.3
Weight2
Key knowledge areas• Understanding roles in open source projects• Understanding common tasks in open source projects• Understanding the various kinds of contributions to open source projects• Understanding the various kinds of contributors to open source projects• Understanding the role of organizations in maintaining open source projects• Understanding the transfer of rights from individuals to an organization maintaining a
project• Understanding rules and policies in open source projects• Understanding attribution and transparency on contributions• Understanding aspects of diversity, equity, inclusivity and non-discrimination
Partial list of the used files, terms and utilities• Software development• Documentation• Designs and artwork• User support• Developers
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Open Source Essentials (Version 1.0) | 055.3 Community Management• Release managers• Users• Project leads and benevolent dictators• Individuals and corporations• Enthusiasts and professionals• Core team members and occasional contributors• Code and documentation contributions• Bug reporting• Forks• Foundations and sponsors• Contribution agreements• Developer Certificates of Origin (DCO)• Coding guidelines• Codes of conduct

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Lesson 1
Certificate:Open Source Essentials

Version:

1.0

Topic:

055 Project Management

Objective:

055.3 Community Management

Lesson:1 of 1Introduction
A key reason to create an open source project is to draw contributions from many different
people. Open source makes it easier to respond to the different needs and interests of the project’s
users and to benefit from their varied skills. Therefore, a diverse community is central to thesuccess of the project. The community is where creative forces come together to make yourproject succeed.
This lesson explains the basic elements of free software and open source communities and how
people in them work together. Of course, because communities are made up of different people,
and because projects have different goals and requirements, each community is unique.

Roles in Open Source Projects
The main output from most open source projects is software, so at the very least, such projects
require programmers, software designers or architects, testers, release managers, and otherexperts in code development. Documentation is usually a part of such projects too, so thecommunity also needs authors, editors, and reviewers.

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Other projects might not produce code, but other “deliverables” such as a book, an art or music
project, or a policy report. Wikipedia is a well-known example of collaboration on an open source
project that focuses on text documents and media. These projects need experts in the design,
production, and delivery of the deliverable.
Communities also benefit from many other general skills, such as marketing and evangelism,
administration, legal advice, artistic talent to produce logos or diagrams in documentation, andskills at maintaining the project’s web site and other communication tools. Open source projects
might organize physical get-togethers and even conferences, in which case they need organizers
to bring those events to life.
The proceeding paragraphs give you an idea of the types of skills a community looks for. These
general roles can be further subdivided into various focused tasks. One simple example of such atask is for some writers to edit the work of other writers.
Among programmers, a range of experience exists. A healthy project always wants some veteranprogrammers (or senior programmers) who know its code and coding standards well, along withnewbies who provide new ideas and simple help such as bug fixes. Some newbies will hopefully
evolve into the next generation of veterans.
Code quality requires careful control over what gets into the central repository shared with users.
Therefore, some veterans get committer status. They are responsible for checking contributions
for quality, usefulness, and conformance to coding standards. They have the priviliges to accept
the proposed code into the trusted repository. Other contributors submit code to the committersfor review.
Many committers and other veterans also mentor new contributors to teach them the standards
and practices needed to get their code accepted.
Some committers fail to appreciate the gift that a contributor is offering. If the contribution falls
short of quality or coding standards, the committer might simply reject it. But the rejection
discourages the would-be contributor and eliminates a valuable educational opportunity.
Remember that good committers are also mentors. So they give the contributor hints about how tobring the code up to standards and work with the contributor over time. If the contribution istruly unusable, the contributor should at least be thanked and encouraged to work on somethingelse for the project. It’s important to help people discover and refine their skills.
When a company starts an open source project, it sometimes appoints committers from its own
staff to ensure that it can control the direction and quality of the project. But often, companies
allow non-employees who show skill and dedication to become committers.
Project leads make critical decisions such as what new features to support. These project leads

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often have non-coding decisions to make as well, such as how to promote the project, resolve
major disagreements, and get funding. Project leads and committers work closely with releasemanagers to decide when a code base is stable and ready to share with the users.
Some projects have a single project lead, often referred to as benevolent dictator. This is often aperson who started the project (Linus Torvalds being a well-known example in the case of Linux)
and who has great authority and even charisma. However, most projects prefer to set up a small
committee of project leads instead of a single benevolent dictator. Even the Linux project has
moved to a committee approach.
Projects might also ask particular contributors to provide user support on the project’s forums.
But healthy projects should have many knowledgeable users who support each other.
We’ll finish this section with a very important role: the community manager. This is someone
responsible for maintaining open and constructive communication and making sure thecommunity progresses toward its goal. The community manager knows how to onboard andmotivate contributors, resolve arguments, protect community members against abuse, andperform other tasks to maintain the community’s health.

Common Tasks in Open Source Projects
In many ways, open source projects involve the same tasks as traditional projects carried out
within a single organization. For instance, all code requires testing. But in some ways, open source
projects differ from proprietary ones, where only a limited set of people are allowed to change thecode and where the source code is often hidden from the public.
For instance, corporations usually assign trained quality assurance (QA) staff to test code. But
many open source projects just ask their users to test each release. (Proprietary projects involve
their users in testing too, in addition to QA.)
Another example of differences: A proprietary project usually assigns paid developers to specifictasks and tells them how much of their time each week to spend on the tasks. Some open source
projects benefit from contributors who are paid by their employers, or sometime even employedby the project itself, and who are assigned tasks in the same way as proprietary developers. But inmost healthy projects, a lot of contributions come from volunteers who just do the tasks as time
permits. Because the project doesn’t rely on all volunteers to complete their projects on schedule,
an open source release might be delayed until the developers feel that the features are ready, or
might be released at fixed times with whatever features are ready.
Communications are critical to both proprietary and open source projects, but are often
conducted differently. Proprietary projects often gather a team in one office and hold regularly

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scheduled stand-up meetings under a development methodology such as SCRUM. Because open
source projects are geographically distributed, such methodologies are rare. Instead,communication takes place online and asynchronously.
In short, free software and open source projects often achieve the same goals as proprietary
projects, but in different ways.
Bug reporting is a critical part of software development that gives rise to its own set of roles.
Someone has to monitor the bug database and assign priorities. If a bug is critical (andparticularly if it can weaken the software’s security), it should be assigned to a competentmaintainer to fix.
Project leads and community managers should look over participation in the project and see
where there are gaps. Are too few people willing to test code? Is documentation missing? Are too
many veterans or senior project members leaving without being replaced? Project leads andcommunity managers can focus on recruiting people to fill needed roles.
Project leads and community managers on large projects often gather metrics as well, to learn
important things such as whether important bugs are getting fixed in a timely manner.

Kinds of Open Source Contributions
As explained in an earlier section, people who put code, documentation, or other items in thecentral repository are called contributors. Project members who approve contributions and accept
them into the repository are called committers. Some members take on other common roles forsoftware development.
Although the term contributor is usually reserved for someone who develops code or another partof the project’s official offering, anyone who participates to the project’s success is contributing insome way and should be thanked for doing so. These more informal contributions include
reporting a bug, answering a question on a forum, donating or raising funds, and promoting the
project to outsiders.
Open source projects, like proprietary ones, ask users what they want in terms of features,
performance improvements, or other changes to the project. These users are making important
contributions by voicing their opinions.

Kinds of Open Source Contributors
Many communities draw contributions not only from individuals, but from corporations who pay
their staff to contribute to a project that the corporation thinks is important to its business.

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Sometimes, having paid contributors right next to volunteers can create tensions. Volunteers
might feel that their work is being exploited, or might be afraid that paid contributors are trying
to bend the direction of the project to favor their employers' interests. A community manager andthe project leads must guarantee that all accepted contributions provide benefits to the wholeproject and its users. Volunteers must also receive motivation to contribute for their own personalreasons, whether out of loyalty to the community or to meet their needs.
Some people contribute to a project regularly and take on long-term responsibilites; these arecalled core team members. Healthy communities also have occasional contributors who reportbugs or post advice on forums, but are not expected to assume responsibility for the project.
Similarly, some contributors will be professionals in their field — whether or not a company pays
them to work on the project — whereas others are amateurs, often called enthusiasts. But you
don’t have to be a professional to take on an important role. You might even become a core teammember or project lead.

The Role of Organizations in Open Source Projects
Although many open source projects are created by zealous individuals or small groups ofvolunteers, they usually seek organizational support when the projects get large. Organizational
support can take many forms. In general, organizations make these contributions because an
open source project can meet their business needs more cheaply and more reliably than
reinventing the same features in proprietary code. The guarantees provided by a free or open
source license are valued by many organizations.
Some idealists distrust corporations or other large organizations and would prefer to keep open
source projects entirely free from their influence. Over the years, this rather simplistic attitude
has become less common. Most open source advocates believe that corporations and otherorganizations can provide crucial underpinnings to open source projects.
Many open source projects start within an organization, and might even be based on proprietarycode that the company decides to open up. To make money, the company may decide to keep firm
control over the project and to break it into open and proprietary parts: This is called the open
core model. Many project founders start as open source but form a company around it, whichmight or might not use the open core model.
Other projects try to ensure that no single company controls their direction. Maintaining
independence usually requires signing up several organizational supporters, so that no one isstrong enough to make a dictatorial decision.
How do organizations support open source? As mentioned earlier, many put paid staff onto

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projects. Additionally, they might hire highly productive individuals who have contributed to theproject as volunteers and have developed expertise in the project. This path to employment is avaluable way for students and other volunteer contributors to advance their careers.
Companies desiring extensions that don’t interest other users should not pressure the open source
project to add the extra features, but should pay their staff to write the features without
contributing them back to the project.
An interesting example of the possible tension created by corporate needs is shown by the famous
Android operating system, based on Linux and developed by Google to drive its mobile devices.
Some changes to Linux made by Google are contributed back to the Linux community, whereas
other changes appear only in Android. The Linux developers sometimes reject changes submitted
to them by Google, just as all projects choose what contributions to incorporate.
There are many reasons for a company, or a group of developers, to make a separate version ofyour code. Ideally, they can meet their needs by adding an optional library or sequence of codethat can be excluded during compilation. But sometimes a group feels a major need that is
incompatible with the direction chosen by project leaders. When a separate version is made, it’scalled a fork.
Forks used to be considered failures of collaboration, but nowadays forks are much more
accepted. Usually, people who make a fork set up a new repository and start a new project. Somepeople work both on the original project and the fork.
(Note that GitHub uses the word “fork” for a very different phenomenon: making a clone or copy
of project code to work in separately.)
In addition to code, many companies contribute financially. They may fund efforts such as
marketing and conferences. They can join the board and offer expert advice on the project’s
direction and strategy.
An example of the importance of such “soft support” comes from the historic Apache web server.
The project took a big leap forward early in its existence when IBM showed interest. IBM lawyers
showed the project how to create legal safeguards, and a meeting paid for by IBM helped theApache leadership create a robust organization.
To maintain independence, many open source projects form a nonprofit foundation or join anexisting foundation. Famous examples of foundations that guide open source projects include theLinux Foundation, the Apache Foundation, and the Eclipse Foundation.
A foundation’s support is valuable because it can provide the logistics that most softwaredevelopers don’t want to deal with: legal support such as trademarking, indemnification, andVersion: 2024-07-26|

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licensing; help with raising money; infrastructure such as bug databases and web sites; and so on.

Transfer of Rights
Just as with books, music, and other creative efforts, software involves a complicated relationshipbetween the developers, the organizations that distribute their contributions, and the generalpublic. Essentially, contributors must take steps to formalize the right of an open source project touse and distribute their code.
Thus, many open source organizations ask contributors to sign a contributor license agreement(CLA). Sometimes, the contributor just gives the code to the project. The project owns the code andall rights to it, just as a proprietary company owns the code that it paid its staff to develop.
Other CLAs leave some rights in the hands of the individual contributors. Contributors might likethis flexibility because they can go on to contribute the same code to another project or build theirown business around it.
To harmonize the different contributions from different people, the license assigned to the code is
crucial. The Linux kernel is one of the projects that leaves ownership in the hands of thecontributors, so that by now many thousands of people own rights to the Linux code. But allcontributors to the core code put it under the GNU General Public License (version 2). Thus, Linux
is free for all to use, alter, and redistribute.
Using a single license for all code in a project is the simplest way to guarantee that noencumbrances hinder the code from being distributed and used. But sometimes a project allows
different parts of code to be contributed under different licenses, usually because the project
wants to take advantage of some pre-existing code that’s already released under a different
license. Licensing experts should make sure that the licenses are compatible.

Rules and Policies
Many online communities have a reputation for unrestricted speech (a cavalier idea that“anything goes”) leading to verbal abuse and bickering. Nowadays, most open source
communities are battling that tendency, which takes hold of people all too easily. In contrast,
modern communities want people to be constructive, civil, respectful, and inclusive of everyone:
all genders, ethnic groups, personality types, and so forth.
Expectations of group members are usually specified explicitly in a code of conduct that explains
how to engage with other people on the project, both online and in person. To be effective, thiscode of conduct has to be enforced by the community manager and project leaders.

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Sometimes, a person who flagrantly mocks or denigrates a fellow community member is expelledpermanently or temporarily. At other times, the community manager or a colleague simply
announces publicly that the behavior violates the code of conduct and might talk to the offender
outside the forum. Often, the offender previously felt frustration, lack of attention, or burn-out,
and community members can help the offender find better ways to express themselves.
In addition to social behavior, communities establish quality standards. The most formal consistof coding guidelines, which try to ensure that all code looks similar. The guidelines may reminddevelopers of good practices such as using brackets around blocks of code, or may specify details
such as how to name variables and what kinds of indentation to use.
Open source communities also have rules around releases of code or other deliverables. Some
projects establish fixed times for releases; for instance, Ubuntu promises a new long term support(LTS) version every two years along with interim releases on a more frequent basis. Other projects
maintain a list of new features and bug fixes they want in the upcoming release and approve therelease when everything is checked off the list. But unlike most businesses, open source
communities don’t usually establish deadlines for participants, because one cannot ask too muchof volunteers.

Attribution and Transparency
In addition to the contributor license agreement mentioned earlier, some projects ask
contributors to sign a developer certificate of origin (DCO). In the DCO, the contributor promisesthat they have the legal right to donate the code.
Why is the DCO important? Imagine this scenario: If a programmer takes code from a proprietaryproduct produced by their employer and contributes it to an open source project, the programmer
violates the employer’s license and puts the open source project at legal risk.
The DCO is supposed to ensure that the contributor actually wrote the code, or obtained it legally.
The open source project depends on the honesty of the contributor who fills out the certificate.

Diversity, Equity, Inclusivity, and Non-Discrimination
Social scientists claim that projects and companies benefit by having many people with different
genders, races, economic backgrounds, nationalities, and abilities. All organizations have anatural human tendency to bond with other people like their current members, so a communitythat values diversity and equity has to consciously train its members to be more open to people
who aren’t like them. The movement to carry out this ideal is called diversity, equity, andinclusion (DEI).

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The code of conduct is the starting point for DEI. It should explicitly welcome people of different
genders, races, etc. Every violation of the code of conduct must be handled promptly withunambiguous disapproval. This is because some minorities have suffered from exclusion andnegative comments their whole lives, and a single bad interaction in your forum could make themdecide they have no reason to participate anymore. A speedy response to aggressions can reassure
them that the community backs them.
But DEI goes much further. The community should reach out to groups who need more
representation. For instance, if you are developing a job search app, you should make sure itshows jobs for low-income people as well as upper-class and middle-class people. You should also
advertise the app among low-income communities and recruit members from those communities
to test it.
Your community might benefit from finding organizations that train people from marginalized
communities, and from which you can recruit new members of your team. Many suchorganizations are established in local areas, and aren’t well-known nationally or internationally.
Understanding the needs of marginalized communities is key. Is your web site accessible to thesight-impaired? Do you translate your documentation into languages with which the target
community is familiar? Perhaps you should create specific forums in other languages.
Most communication in open source communities is asynchronous and online. But if you havemeetings or synchronous chat sessions, think about where people are geographically and findways to include everybody. For instance, when people from many countries and regions arecommunicating in English, try to keep the vocabulary and grammar simple.
Finally, if you have members of some minority on your team, make sure to listen to them. One
well-known symptom of exclusion is discounting what minorities say or just underappreciating its
importance.
On the other hand, don’t burden minority members with the need to explain their communities'
needs — everybody should be tasked with that research. The minority members might do valuable
outreach for you, but don’t pressure them to do so. Each person should have the equal
opportunity to participate the way they want, without having to be a token minority.

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Guided Exercises
1. Why don’t all contributors give their code to the project and relinquish all rights to the code?

2. If someone wants to help the project but can’t program, what are some ways they can help?

3. Why do many open source projects join a foundation?

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Explorational Exercises
1. You are a committer on your project. Someone submits code that was taken from anotherproject (but the contributor has the rights to it). The code is formatted completely differently
from the rest of your code. What do you do?

2. You created a proprietary software product and want to contribute parts of it to an open source
project. Under what circumstances can you continue to offer your proprietary product?

3. Two people on your mailing list start to argue over a feature in your code. The argument
gradually gets more heated until one person calls the other an idiot. How can you handle thesituation?

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Summary
In this lesson, you learned what it’s like to be part of a community and how communities remain
productive. You learned different types of contributions, contributors, and roles. You learned how
communities control the right to use contributions. You learned about rules in a community andhow they protect everyone, including people of different races and genders, from verbal abuse.

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Answers to Guided Exercises
1. Why don’t all contributors give their code to the project and relinquish all rights to the code?
The contributor might want to contribute the same code to a different project or release a
product based on the code, and therefore wants to keep some rights.
2. If someone wants to help the project but can’t program, what are some ways they can help?
There are many roles for contributors besides coding. A few such roles include documentation,
testing and bug reporting, community management, participating in forms, promoting the
project, and doing artwork.
3. Why do many open source projects join a foundation?
A foundation handles many legal, financial, and other tasks that the project’s community might
have difficulty doing.

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Answers to Explorational Exercises
1. You are a committer on your project. Someone submits code that was taken from anotherproject (but the contributor has the rights to it). The code is formatted completely differently
from the rest of your code. What do you do?
Your project’s coding standards should clearly explain how to format the code. Thank thecontributor, point them to the standards, and ask them to reformat the code. Sometimes,
automated tools exist to reformat code as you want it. If the contributor doesn’t have time to do
the reformatting, look for a junior member of your team who can do that job.
2. You created a proprietary software product and want to contribute parts of it to an open source
project. Under what circumstances can you continue to offer your proprietary product?
The answer depends on the contributor license agreement. If the CLA requires you to hand thecode over to the project, granting them all rights, you might not be able to continue offering
your proprietary product. However, if they let you keep your rights to the code, you can release
it under any license you like in your proprietary product.
3. Two people on your mailing list start to argue over a feature in your code. The argument
gradually gets more heated until one person calls the other an idiot. How can you handle thesituation?
Anyone who notices the escalation and the abusive comment should react as quickly as theycan. The community manager is ultimately responsible for repairing the damage. The person
who intervenes should post a comment to the whole list saying that the behavior violates the
project’s code of conduct (which hopefully rules out such behavior.) The person intervening
can also reach out to the people on each side separately to make sure they are satisfied by the
resolution of the argument and understand how to discuss disagreements constructively.

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Topic 056: Collaboration and Communication

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056.1 Development Tools
Reference to LPI objectives
Open Source Essentials version 1.0, Exam 050, Objective 056.1
Weight2
Key knowledge areas• Understanding common software development tools• Understanding common deployment environments• Understanding common types of software testing• Understanding the concepts of Continuous Integration and Continuous Delivery (CI/CD)
Partial list of the used files, terms and utilities• Integrated Development Environments (IDEs)• Linters• Compilers• Debuggers• Unit testing• Integration testing• Acceptance testing• Performance testing• Smoke testing• Regression testing

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Open Source Essentials (Version 1.0) | Topic 056: Collaboration and Communication• Production, staging and development systems• Local development systems• Remote development systems• CI/CD pipelines240|

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Lesson 1
Certificate:Open Source Essentials

Version:

1.0

Topic:

056 Collaboration and Communication

Objective:

056.1 Development Tools

Lesson:1 of 1Introduction
There are thousands of software development tools, both open source and proprietary. And why
not? Programmers love to develop tools for themselves and their colleagues; it’s only natural thatthey’d invest a lot of time trying to find a tool that works better, removes some annoyance fromtheir workflow, or makes deployment easier.
This lesson focuses on the development process and explains how various types of development
tools fit into it. Few specific tools will be named, because any one of them could possibly be
flagged as deprecated or obsolete, and be replaced by a new favorite by the time you read thislesson.

Goals of Development
Programming tools juggle multiple goals that sometimes conflict with one another. Here are somesample development goals:• Produce robust, accurate programs.
• Produce programs that run fast.
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Open Source Essentials (Version 1.0) | Topic 056: Collaboration and Communication• Produce programs that scale well.
• Produce programs that are highly adaptable to different types of users, different devices (suchas laptops, cell phones, and tablets), and different environments.
• Speed up the development process.
• Speed up deployment of newly developed features or bug fixes.
• Reduce tedious work, as well as the number of clerical programming errors that slip through tothe test stages of the program.
• Support legacy code and devices that the organization has trouble replacing.
• Work together with other familiar tools.
• Allow for easy roll-back in case of errors or changes in plans.
These goals, and others, lead to the processes described in this lesson and the resulting
development tools.

General Development Processes
This section contrasts two general models of historical importance: the waterfall model(introduced in an earlier lesson) and continuous integration/continuous delivery (CI/CD).

Waterfall Model
Although the waterfall model is still widely used, especially by large organizations, it has fallenout of favor among many developers. This model was popular from the 1950s through the 1970s.
Elements of the model can still be widely found today, such as formal definitions of requirements
and testing programs just before their release (quality assurance).
Even at the time that the term “waterfall” was coined for this model, it had become widelydiscredited. Problems included:• Changing requirements was difficult once development started.
• Requirements and designs were often misunderstood, because plain-language text can be
ambiguous. This problem led to products that didn’t meet the intended requirements, and took
months to fix.
• The process was slow. A new release might be achieved only once a year, or even less often.
• Bugs caused by the interaction of different modules were hard to catch until late in the process,leading to further delays.
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quality of the product as well as organizational esprit de corps.

Principles of Continuous Integration/Continuous Delivery (CI/CD)
The waterfall model was challenged in the 1970s by a series of movements that led to the mostcelebrated (if not universally used) model today: CI/CD. Stages in the adoption of the CI/CD
practices include the Agile Manifesto, released in 2001, SCRUM, and DevOps. The new model isfounded on the principles of tight communications among team members, involvement by theend user or customer, rapid roll-out of bug fixes and new features, and rigorous ongoing testing topreserve quality in a fast-moving — sometimes even chaotic — environment.
CI/CD automates as many steps as possible in the stages that range from writing code to deploying
the completed program to end users. CI/CD requires defining each step formally and replacing ahuman action (such as installing software by hand) with a procedure run by a program. Thus,
CI/CD is part of a movement known by the phrase “everything as code” and “infrastructure ascode.”
Furthermore, once a team has incorporated its processes into code, these processes can be fixed,
upgraded, and recorded historically just like code. Anything written by the team, whether
programs, automated procedures, or documentation, should be stored in a version control system,
which is described in an upcoming lesson.
When several procedures are automated, they can run in sequence. Thus, teams often talk about a
CI/CD pipeline, which means that one successful step in the pipeline automatically triggers one ormore subsequent processes. A pipeline must be monitored in an automated fashion so that any
failure along the way causes the pipeline to stop and notify team members of the failure.
Although the following sections discuss CI and CD separately, they tend to be combined, and thedividing line between them is blurry.

Continuous Integration (CI)
Continuous integration refers to the fast incorporation of small changes into the code. The central
repository used to create the product for end-users is known as the core repository (or core repo).
Each programmer creates a personal workspace (often called a sandbox) on their computer andpulls from the core repository the files they need to fix or upgrade.
The programmer could use a personal laptop or desktop (known as a local development system),
downloading relevant parts of the core repository and then uploading changes after local testing.
Alternatively, the programmer could take advantage of the popular trend called “cloudcomputing” and work on a shared system run by their organization, a remote development system.

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The programmer generally checks for errors using a debugger, a separate program that runs the
programmer’s work in a controlled environment. We’ll look later at debuggers and other tools forcatching errors.
To catch errors as early in the development process as possible, the programmer also runs tests on
the code before uploading it to the core repository. These are called unit tests because eachfocuses on one tiny element of the code: For instance, did a function increment a counter as it was
supposed to?
The last stage in CI is checking the programmer’s changes into the core repository. At this stage,
tools run integration tests to make sure the programmer hasn’t broken anything in the project as awhole.
No matter how far automation has come, some expert member of the team should intervene at
the point of integration to make sure the change is desired by the team. Automated tests candetermine that nothing has broken, and even whether the change creates the desired effect in the
program. But these tests can’t check for all the principles considered important by the team.
Therefore, before proceeding to deployment, a team member should check security, adherence tocoding standards, proper documentation, and other principles. (Not surprisingly, tools exist forsome of these tasks too; we’ll look at them later in this lesson.)
A lot of testing takes place during CI, and it has to happen both fast and reliably to support thepace of modern development. Therefore, modern tools for integrating code and running tests areautomated. A programmer should be able to run a whole suite of unit tests through a single
command or a click of a button.
Generally, a partial or full integration test runs whenever the programmer uploads code to thecore repository. Any errors caught by the tests can be reported quickly to the programmer.

Continuous Delivery (CD)As explained in the previous section, CI consists of automated procedures that lead up to a newversion of the program in the core directory. Continuous delivery refers to anything that happens
after that stage to bring the new version out into the field where end users can benefit from it. The
D in CD is sometimes expanded to “development” or “deployment” in addition to “delivery.”
The main tasks of CD are to test the code thoroughly and to upload it to the users' computers or an
application repository.
The CD phase runs a battery of tests to provide maximum assurance that the product works well.
A larger set of integration tests might be run, along with a number of other tests to determine

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impacts on the users, performance, and security. A later section in this lesson describes some ofthese tests.
Testing should be done on different systems from the production systems that serve users. Not
only could a catastrophic flaw bring down a production system; it might corrupt user data.
Furthermore, tests compete for system time and degrade performance for users.
So for testing, it’s best to set up a complete computing environment that mirrors your production
environment, with similar hardware and software. The intermediate environment where testingruns before deployment is often called a staging environment.
Of course, it wouldn’t be practical to make the test environment the same size as the production
environment, but the essential elements of the production environment (such as databases)
should be included.
One requirement of CD automation is to distinguish between the test and production
environments. All the code installations and processes should be tailored to the target
environment.
CD offers the most potential for rapid development when the code is a service running on theorganization’s own systems. If you’re a retail site, for instance, offering an interactive web page,
you have access to all your web servers. You can update them several times a day, if you want,
and roll back changes quickly if they turn out to produce problems for users.

Common Software Development Tools
These sections present common types of tools used by programming teams at three levels: code
generation, testing, and deployment.

Compilers
A fundamental programming tool is the compiler, which turns very sophisticated, high-level
programming languages into the instructions running on the computer processor.
Computers run machine code, which consists of strings of bits (ones and zeros) that the processor
turns into instructions and data: loading a value from memory into a register, adding the values of
two registers, etc. Processors are distinguished by the different formats and sets of instructions
they have, so they have different machine code as well. Vendors try to invent new processors that
use the same machine code in order to allow customers to run their old programs on the newprocessors. When vendors do so, we speak of families of processors.
The next stage in the early years of programming was assembly language, which provided human-

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readable terms, such as ADD, for each instruction. Programmers wrote in assembly language andsubmitted their code to a tool called an assembler to translate the assembly language into machinecode. Machine code is also called machine language.
Then, higher level languages were created. Nowadays, you can create complex control flows
without even specifying their details; you can just indicate your desired results. These programs
require a compiler to turn source code into machine code. The compilers can perform quite
intelligent transformations and optimizations.
Many languages have multiple compilers available. You can find a choice of compilers for very
popular languages, such as C and Java. In the free and open source community, most people use
either the GNU Compiler Collection (GCC) or the LLVM compiler for C and C++.
Originally, a compiler would compile each file of source code to produce an intermediate object
file, then combine all the object files into one program by invoking another tool called a linker.
Modern compilers can compile multiple files at once in order to perform optimizations that crossthe boundaries of files.
Compilers used to compile into assembly language, which could be useful because each type ofcomputer processor supported a different machine code but may support the same assembly
language. There are multiple variants of assembly languages. The last step in compilation andlinking was to produce machine code. As with linking, modern compilers know how to assemble
the code into machine code.
But there is another stage in many modern languages: intermediate code, usually called byte code.
This code has been compiled into a binary format that is high-level enough to be portable. For
instance, the Java language is compiled into byte code so that the program can be loaded onto
many different types of processors.
In producing byte code from source code, the compiler has done much of the work. Each
computer then hosts its own version of a program called a virtual machine that completes thetransformation from byte code into a set of instructions that the virtual machine can execute.
Sometimes, byte code is compiled into machine code, too. Going from byte code to a set of
instructions is more convenient for end users than going from a high-level programming language
to machine code. This was a great advantage for Java when it was invented, because its designers
wanted it to run within a virtual machine plug-in for web browsers, where the user’s processor
and operating environment could be quite varied.
Java designers promoted the benefits of byte code through the marketing phrase “Compile once,
run anywhere.” Some other advantages of byte code emerged later. New languages could becreated that provided a very different experience to programmers (hopefully making the job ofprogramming easier and producing more maintainable code) while creating the same byte code
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that Java virtual machines supported. Functions from these languages were easy to mix into
existing Java programs.
Finally, there are some languages, such as Python, for which you don’t have to compile sourcecode at all: You simply enter statements into a processing tool called an interpreter, whichconverts the code directly into machine code and executes it. Interpreters are slower thancompilers, but some have become efficient enough that they don’t impose much of a performance
penalty. Still, some popular libraries in the Python language include functions that are accessible
to developers in the interpreted language but are programmed in the C language, to speed up
execution.
Many interpreted languages provide compilers too. They produce either byte code or machinecode, which then executes more quickly than the interpreter.
There are build tools to help programmers manage files and functions. A complex program might
contain hundreds of files, and the programmer will need to compile different combinations offiles using different compiler options at different times (for instance, to support debugging). A
build tool lets the programmers store different options and combinations of files, and easilychoose the desired type of build. Maven and Gradle are common build tools for Java and related
languages.

Code Generation Tools
The programmer doesn’t have to start coding with a blank screen. Recently, services have sprungup that generate code based on your plain-text description of what you want. This a form ofgenerative AI, and like other such services, some people complain that it draws on the work offormer programmers without compensation and produces less robust source code (so far). Asidefrom ethical controversies, many programmers say that automatic code generation has greatly
improved their productivity.
One form of code generation that has been available in many programming languages for many
years is refactoring. It examines a large program, which can easily evolve over time into a tangleof files and functions. Refactoring moves functions around to create a more logical structure to
the program in the pursuit of improved maintainability and reduced duplication of source code.
Some programmers are tasked with reproducing the functioning of other code. They may need towrite a new program to replace a legacy program with missing source code that must be retired.
Or they might be mimicking a competitor’s program. This kind of research is called reverse
engineering. One useful tool for this purpose is a disassembler, which turns machine code into
assembly language. There are also disassemblers for byte code.

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Debuggers
Most programmers spend more time debugging than coding. People just don’t think perfectly
logically, and therefore forget some detail that the computer requires to run the program the way
you want. Thus, your code is likely to fail at first try, and you can benefit greatly from a debugger
to uncover the error.
A debugger supports intensive research efforts that can cut hours off of the process for finding
errors.
A programmer can ask the program to stop at some key place in the program (a breakpoint), suchas the beginning of a function or loop. The debugger can display the values of variables and evencomputer registers at the current point in the program. The programmer can also run eachstatement, one at a time, and see the results (single stepping). If the programmer wants to see
when and how a variable changes during the run, they can set a watchpoint.
The most prominent debugger in the free and open source world, particularly for C and C++, is the
GNU debugger, which works with the GNU compiler mentioned earlier. Other languages also havededicated debuggers.

Analytical Tools
Although debugging can usually uncover bugs fairly quickly, it’s better to eliminate spelling errors
and other basic problems earlier in the programming process. Many ingenious analytical tools
exist to check a program. Static analysis examines the code of a program. Dynamic analysis runs a
program and checks for problems during its execution.
One of the earliest forms of static analysis was called a linter. It can detect, for instance, if you
assign the value of a floating-point variable to an integer. This might or might not produce
problems, and might or might not be caught by the compiler. In production, it could lead toincorrect results.
Nowadays, most compilers can do the job of a linter. Some compilers, such as the one for the Rust
language, are notable for their strictness in rejecting poorly written code.
Many other types of analytical tools run separately from the compiler. For example, security
analysis tools can find problems that make a program vulnerable to hacking. A common error bydevelopers, for instance, is when their code calls a function and doesn’t check whether thatfunction returned an error.

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Integrated Development Environments (IDEs)
Many programmers use text editors to enter and edit their code. Text editors are different fromword processors, which introduce a lot of formatting (such as italic and bold, bullets andnumbered lists, etc.). The text processor produces unadorned text, which programming languages
require.
There are also sophisticated tools dedicated to helping programmers develop their programs.
These tools are alert to the programming language in use. For instance, if you start to type thename of a variable of function, the tool can suggest a completion. These tools can check for errors
while you’re coding, format the code in a consistent and pleasing way, run analytical tools anddebuggers, compile the code, handle check-ins to version control systems. and take care of othertasks for you. Therefore, they are called integrated development environments (IDE).
Eclipse is a popular open source IDE.

Common Types of Software Testing
Testing is a major part of software development. Programmers run unit tests as they develop thecode. Other types of testing typically run when a programmer checks code back into the core
repository, or during deployment.

Unit Testing
We’ve seen that a programmer should take great care to find errors before submitting code for
integration into the core repository. Unit tests are crucial to catching errors.
Writing these tests is both an art and a science, and the volume of test code might exceed thevolume of production code. There is even a development model called test-driven development(TDD), where programmers write tests before writing the code they want to test. Proponents of
TDD claim it plugs gaps in testing and helps ensure that the code does what the programmer
wants it to do.
It’s important to test for things that go wrong during program execution, as well as things that goright. If the user, or another part of the program, submits invalid input to a function, it’s
important for the function to catch the problem and report an appropriate error message.
JUnit is a popular open source tool for running unit tests on Java programs.

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Integration, Regression, and Smoke Testing
While unit tests focus on the individual actions of particular functions, the team should also run
tests at a higher level to make sure the product, as a whole, works properly. The tests generally
imitate user behavior. For instance, in a restaurant management application, tests could check
whether the user gets the item they requested.
When a change to a program breaks some function that worked before, the failure is called a
regression, and the tests are called regression tests.
As a team prepares a product for release, the first stage of testing is often very short. The teamchecks for the most important activities performed by a program and stops testing if any errors
arise, thus saving time. This kind of testing is called a smoke test, because an application thatmalfunctions so easily is like a bad device that catches on fire.
Some products involve user interaction; web and mobile applications are common examples.
Therefore, tools have been created to emulate user interactions. The test runs automatically,
triggering the code that would have run if a user pressed the button. Selenium is a popular tool inthis category.

Acceptance Testing
Programs with a user interface need an extra level of testing beyond proving that they reactproperly to certain inputs. The programs must also look right on the screen. Acceptance testing
checks the impact of the program on the user. Quality assurance teams generally run these tests
after integration and regression testing demonstrate that the program is formally correct andmeets user expectations.

Security Testing
Security is obviously critical, and even a tiny security failure can expose an organization to major
damage. We’ve seen that programmers can run analytical tools to check the security of the code.
In the quality assurance stage, tests can also determine whether the program has vulnerabilities.
The tests run the program with malicious inputs and make sure the program rejects the input
without failing, performing unintended actions, or revealing sensitive information.
One kind of test that has proven valuable in some situations is fuzz testing. The test framework
simply generates strings of random garbage and submits them as input to the program. This mightseem to be a waste of time, but often turns up vulnerabilities that ordinary testing does not.

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Performance Testing
After the program is judged by other tests to work correctly, teams should determine whether itruns fast enough. Performance testing requires an environment similar to the ones where theusers will interact with the program. For instance, if users will submit requests from a long
distance over a network, performance testing should also be done over a long-distance network.
Some programming libraries are tested through benchmarks: standard tests used to compare
different libraries or different versions of the same library.

Common Deployment Environments
A CI/CD tool allows sophisticated ways to construct pipelines. Like computer programs, a pipelinecan contain tests and branches. By branching, you can perform one set of activities in the test
environment and another in the production environment. You can use the tool to automaticallyinstall the correct database or other software needed for different programs.
CD overlaps with DevOps. In cloud environments, CD and DevOps tools create the virtualcomputer systems in an automated fashion with all the components needed for the programs torun. Automated tools (sometimes called orchestration tools) check for the failures of virtual
systems and automatically restart them.
The main job of the CD tool is to launch and step through each pipeline. The tool checks the resultsof each stage of the pipeline, and chooses whether to proceed or stop. The tool also allows
scheduling, and logs its activities.
Often you have to run a task repeatedly with minor variations. For instance, teams distinguishbetween deploying to a test environment and deploying to production. Therefore, CD tools
provide parameters that you can fill in with different values when you run the pipeline.
Sometimes, a process requires commands that traditionally were entered at the terminal. Thus, a
CD tool provides mechanisms to run arbitrary commands. Usually, it provides hooks such as
preprocess to run commands before a stage of the pipeline and postprocess to run commands
after a stage of the pipeline.
Jenkins is probably the most popular open source tool for the orchestration described in thissection.

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Guided Exercises
1. What are some ways to check a program’s security?

2. Why would you write multiple unit tests for a single program function?

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Explorational Exercises
1. Your team has inherited an old application that runs slowly and is hard to add features to.
What are some ways to improve the application, without throwing it out and writing a new one
from scratch?

2. In large projects, frequently, Team A wants a feature implemented in a part of the system
maintained by Team B, but Team B doesn’t see the feature as a priority. How can Team A code
the feature as part of Team B’s project?

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SummaryThis lesson has laid out the types of tools used throughout development: compilers and other code
generation tools, analyzers, tests, and CI/CD tools that automate integration and delivery. There
are many options for each of these activities, and a tool that is popular today may be replaced in ayear. Understanding how these tools all fit together in the development process helps you identify
what you need.

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Answers to Guided Exercises
1. What are some ways to check a program’s security?
First, human experts can examine the code.
Many static and dynamic analysis tools exist to catch poor programming practices that expose
a program to security threats.
Other tools submit malicious input to running programs and check their reactions.
2. Why would you write multiple unit tests for a single program function?
A program function usually has to run on many varieties of input, and each variety deserves its
own test. For instance, the function might handle an input value of zero in a special way. You
also need to anticipate invalid input and write tests to show that the function handles it
appropriately.

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Answers to Explorational Exercises
1. Your team has inherited an old application that runs slowly and is hard to add features to.
What are some ways to improve the application, without throwing it out and writing a new one
from scratch?
First, make sure the project is under version control, if it wasn’t placed there already.
After adding a new feature, run regression tests to determine where the program fails, andassign programmers to figure out what functions are responsible. These functions can beselectively replaced.
Performance testing can identify particular functions that run slowly, so you can focus yourefforts on fixing or replacing the most inefficient code.
If the code is in a language that is no longer popular, consider adding features in a language
preferred by the team. Make sure that functions in the new language can be integrated with theold functions.
2. In large projects, frequently, Team A wants a feature implemented in a part of the system
maintained by Team B, but Team B doesn’t see the feature as a priority. How can Team A code
the feature as part of Team B’s project?
Team B can allow Team A to create a new branch, code the feature, and submit the branch toTeam B to merge into its project. Team A must not be empowered to do anything they want,
however. Team B should provide documentation and help for Team A to follow project
standards. A member of Team B must also review Team A’s submission, and run all the usualforms of integration testing.
This form of collaboration is sometimes called InnerSource, because it resembles open source
but takes place within a single organization.

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Reference to LPI objectives
Open Source Essentials version 1.0, Exam 050, Objective 056.2
Weight3
Key knowledge areas• Understanding source code repositories (public and private)• Understanding the principles of source code management and repository organization• Awareness of common SCM systems (Git, Subversion, CVS)
• Awareness of the terms Version Control System (VCS), Revision Control System and Source
Code Management systems (SCM)
Partial list of the used files, terms and utilities• Source code repositories• Commits, Branches and Tags
• Feature, development and release branches• Subrepositories• Code merges

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Lesson 1
Certificate:Open Source Essentials

Version:

1.0

Topic:

056 Collaboration and Communication

Objective:

056.2 Source Code Management

Lesson:1 of 1Introduction
Anyone who has ever edited a text document in a team knows the problems with suchcollaboration: Which version is the current one? Where is this version saved? Is it currently beingedited by someone? Who has made which comments or changes to the text — when and why? The
result is often differing versions of the document and, in the worst case, a collection of versions
that nobody has a grasp of.
Now imagine a software project with hundreds of files, on which developers from all over theworld are working by developing new features, fixing bugs, splitting off parts and developing
them separately, and so on. Such a development process is no longer manageable without suitable
tools.
Special software for source code management (SCM), also known as version control systems (VCS)or revision control systems (RCS), provides a remedy here. It eliminates the problems that were
just outlined.
In the world of software development, SCM stands as a fundamental pillar, safeguarding the
integrity of your codebase. Picture it as a diligent guardian, meticulously tracking every tweak

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and turn made to your source code over time.

Source Code Management System and Repository
The source code management system is the heart of a software project. Although important work
goes on in discussion forums and other places, the SCM system represents both the history of the
project and its current state as a living entity.
The source code repository is a kind of digital workshop for a project. Just as a physical workshop
stores all the tools and items needed to manufacture a workpiece, a source code repository stores
all the files, documents, and code related to a software project. It provides a structured
environment for organizing and managing the project’s assets.
Information is normally stored in the form of a directory tree. SCM systems typically use a clientserver model, where any user can pull data from the repository as well as push data into it. The
system keeps track of who made each change and when it was made, ensuring transparency andaccountability within the team.
Imagine you’re working on a project with multiple developers, and a bug is discovered in thecode. With an SCM, you can easily examine the changes between versions to pinpoint the specificcode change responsible for the bug.
Because the system remembers each version of the files as they change, a user has access to any ofthese versions and can revert to earlier versions (in case incorrect changes were made). So therepository is also a kind of archive, granting access to every change ever made to the project, andto the status of the project at any moment in its history.
SCM systems save space by keeping track of changes to a file instead of storing the complete fileeach time a change is made. This efficient storage method ensures that historical versions areaccessible without consuming excessive resources.
Many tools, such as continuous integration/continuous delivery (CI/CD) and testing, revolvearound the SCM system. People also build their reputations through the system by making theircontributions visible to everyone. Therefore, source code management is not just about tracking
changes; it’s about preserving the integrity of your codebase and fostering collaboration amongdevelopers, ensuring that your projects can evolve in a dynamic and ever-changing landscape.
Popular SCM systems include Git, Subversion, and CVS. Like many other software functions, SCM
is now often provided by specialized vendors. In other words, it is Software as a Service (SaaS) ora “cloud” service: Participants have the software on their local systems to manage their personalchanges, but upload their changes to a central repository that benefits from typical cloud features
such as 24/7 uptime, backups, and secure access.
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Millions of developers now use cloud services, notably GitHub. GitLab is an alternative based on
open source code. Both GitHub and GitLab allow people to work in the vendor’s cloud repositories
or set up a local version of the SCM system. One advantage of working on those systems is the
reputation one can gain through their “star” systems, which allow users to rate each other’s work.
The cloud services add extra attractions such as change request trackers, rating systems, wikis,
and discussion forums.
Repositories can contain both personal and corporate projects, meaning they are not necessarily
exclusive to enterprise use. Any developer who wants to start a development project or work on
an open source project, copying and modifying it according to their needs, can do so. In all thesecases, it is important to have firm control over who can access your repository.
Understanding the terminology surrounding version control and source code management isessential in navigating its use. In the following sections, we take a closer look at some of theseconcepts and terms.

Commits, Tags, and Branches
A developer creates a commit each time a change is uploaded into the respository. Commits
represent snapshots of changes made to the codebase at a particular point in time. Each commit
includes metadata such as the author’s name, a timestamp, and a descriptive message explaining
the changes. Commits help developers track the evolution of the codebase and understand thehistory of specific changes.
Consider a team of developers working on a web application. Each time they make changes to thecodebase, they create a commit to document those changes. For instance, someone who adds a
new feature to the application might create a commit with a message like “Added user
authentication feature.” This commit captures the state of the codebase after the feature was
implemented.
When a developer fixes a bug, the commit message usually refers to the number of the bug in the
project’s bug tracking system.
Tags are named references to specific commits. They typically mark significant points in the
project’s history, such as releases or milestones. Tags provide a way to label and refer toimportant versions of the codebase, making it easier to manage and navigate the project’s history.
Branches come into play when developers need to work on different tasks concurrently. Branches
are independent lines of development that diverge from the main codebase. They allow
developers to work on features or fixes in isolation without affecting the main code until they are
ready for integration. Branches help organize development efforts and facilitate collaboration

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among team members.
For example, if one developer is working on adding a new feature to the application while
another is fixing a bug, they can each create separate branches to isolate their changes. Once theirwork is complete, they can merge their branches back into the main codebase (Branches).

Figure 16. Branches

When multiple people are working on the same file, or are checking files into another branch,sometimes it will happen that two people made a change to the same line of a file. When thesecond person to make a change tries to check it in, the system warns of a conflict.
Some VCSes simply don’t let a developer check in a file if it contains a conflict with the current
version in the repository. The developer must check out the current version and figure out how toresolve the conflict, then check in a new version.
Cloud-based systems offer merge or pull requests. These are created by a developer who has
worked on a local system or branch and believes their changes are suitable for inclusion inanother branch. The developers for the target branch decide whether to accept the request.

Subrespositories
It often happens that the code of another, independent project (e.g., a media player) is required
for the development of a software project (e.g., a complex website). Instead of copying the code of
the media player in part or in full into your own project, many VCSs offer the feature ofsubrepositories, also known as submodules.
In our example, the repository of the media player is integrated into the repository of the website

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as a subrepository. It then appears as a separate directory in the directory tree. This means thatthe code base of the media player is fully available, but remains independent. If required, it caneven be updated from the original repository of the media player.
This capability proves valuable for handling intricate projects with numerous dependencies or
integrating third-party libraries and frameworks into a codebase. Submodules enhance project
organization and facilitate collaboration by allowing developers to work with interconnected
codebases efficiently.

General Use of a Source Control Management System
Each participant in a project starts by creating an identity, normally tied to the participant’s
unique email address. A cloud-based system manages identities through accounts, as social media
sites and other organizations do.
New developers go through a sequence like the following, when using an SCM system:
1. Install the SCM software, if it is not already provided on their operating system.
2. Get the entire project onto the local system one time, also known as cloning.
3. From this step onward, work locally (in one or more branches, if necessary), and push changes
to the repository.
4. Pull the recent version from the repository before the next working session.
Project managers decide whom to trust and give access to the repository. Senior devoélopers havethe important responsibiilty of deciding when changes submitted by other contributors are readyto go into the main branch of the respository.
On cloud-based systems, a project owner can control the accessibility of a repository by setting its
visibility to either public or private. Public repositories grant read access to anyone on theinternet. Private repositories, however, limit access solely to the owner, individuals with whom
the owner have explicitly shared access, and, in the case of organization repositories, specificmembers of the organization.
Imagine a team of developers working on an e-commerce website. They decide to add a newfeature that allows customers to track their orders. To implement this feature, they create afeature branch with a name such as order-tracking, where they can work on the necessary codechanges without affecting the main codebase. Once the feature is complete and tested, they merge
this branch into the main development branch for further integration and testing.
The main development branch serves as a central hub where all the new features are brought

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together for testing. For instance, if multiple developers are working on different features
concurrently, they can merge their feature branches into the development branch to ensure thateverything works together smoothly. This integration process helps identify and resolve any
conflicts or compatibility issues early on.
When it’s time to release a new version of the e-commerce website, the team creates a releasebranch, such as v2.0, from the development branch. They focus on stabilizing the codebase, fixing
any last-minute bugs, and conducting thorough testing to ensure a smooth release. Once therelease is ready, the code from the release branch is deployed to production, and the cycle begins
anew.

Common Version Control Systems
Some of the best-known version control systems are Git, Subversion (also known as SVN), andCVS. All of these are open source.
Git is a distributed version control system widely used in software development and other fields.
When using Git, each developer has a complete copy of the codebase on their computer.
This decentralized approach enables developers to work offline and collaborate seamlessly,
without relying on a central server. That is, developers can work independently on different
features or fixes and merge their changes together seamlessly. Even if the central server goesoffline, developers can continue working and share updates with each other.
Consider the development of the Linux kernel, which initially relied on a centralized version
control system called BitKeeper. When BitKeeper’s free-of-charge status was revoked, Linus
Torvalds and the Linux community developed Git as a distributed alternative. This decisionenabled non-linear development and the efficient handling of large projects such as the Linuxkernel. The success of Git for the Linux kernel — an extremely complex project with thousands ofdevelopers and innumerable branches — shows the power and scability of Git.
Most software development these days uses Git. Extremely popular SaaS offerings are built
around it.
Git treats conflicts by giving the developer a file with both versions of the changed line, clearlymarking which version of the file the lines are from. The developer must decide how to resolve
the conflict and check in a coherent version of the file.
Subversion (SVN) was probably the most popular SCM system before Git was invented. Unlike Git,
Subversion is centralized: The version history resides on a central server. Developers connect tothis server to make changes, ensuring that everyone is working with the latest version of thecodebase.
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Assume you are part of a team working on a project using Subversion. Each time you need tomake changes to the codebase, you connect to the central SVN server to check out a working copyof the code. This ensures that you’re working with the most up-to-date version of the project. Aftermaking your changes, you commit them back to the server, updating the central repository withyour modifications. The centralized workflow helps maintain consistency and ensures thateveryone is working towards the same goals.
Before Subversion, CVS was a very popular, centralized version control system. It had design
problems that led to the design of Subversion as an alternative.

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Guided Exercises
1. Name three core features of SCM systems.

2. Describe the concept of tagging in SCM systems and explain why it is important for managing
software releases.

3. What is the difference between a branch and a subrepository in a SCM system?

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Explorational Exercises
1. Compare Git and Subversion (SVN) in terms of their architecture and workflow.

2. What is the “index” or “staging area” in Git?

3. Outline the Git trunk-based branching strategy.

4. Which of the following SCM systems are open source?
Git
Mercurial
Subversion
GitHub
Bitbucket
GitLab266|

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SummaryThis lesson explained the central role of source code management systems in modern softwaredevelopment. You learned the basic terms and ways of using the system, including repository,
branches, tags, and merges.

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Answers to Guided Exercises
1. Name three core features of SCM systems.
◦ Logging changes to the source code
◦ Management of (simultaneous) access to the source code by developers◦ Ability to restore any state of development of the files or the entire project
2. Describe the concept of tagging in SCM systems and explain why it is important for managing
software releases.
Tagging is the practice of assigning descriptive labels or names to specific commits within thecodebase, serving as markers for significant points in the project’s history, such as releases ormilestones. These tags offer a convenient means of referring to particular versions of thecodebase and monitoring the project’s evolution over time.
3. What is the difference between a branch and a subrepository in a SCM system?
A branch is a parallel development line in a project, such as for bug fixing or developing newfeatures, which is usually merged back into the main development branch as soon as the task
has been completed. A subrepository or sumbmodule is an independent project whose
repository is integrated into a project in order to access its code base. The subrepository
appears as a directory in the directory tree of the project and remains independent.

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Answers to Explorational Exercises
1. Compare Git and Subversion (SVN) in terms of their architecture and workflow.
Git is a distributed version control system (DVCS), allowing each developer to have a complete
copy of the codebase and work even offline on the source code. Git has gained widespread
popularity among developers due to its speed, flexibility, and robust branching and merging
capabilities. SVN is centralized VCS, with the version history residing on a central server. It
remains popular in certain enterprise environments due to its centralized nature and maturefeature set.
2. What is the “index” or “staging area” in Git?
The index or staging area is an intermediate layer between the local working copy of the
project and the current version on the server. It is a file in which all the information for auser’s next commit is stored.
3. Outline the Git trunk-based branching strategy.
Trunk-based development is a strategy that emphasizes frequent integration of changes into
the main codebase (trunk). Developers work on short-lived feature branches and merge theminto the trunk multiple times a day, ensuring continuous integration and rapid feedback.
4. Which of the following SCM systems are open source software?
Git

X

Mercurial

X

Subversion

X

GitHub
Bitbucket
GitLabX

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056.3 Communication and Collaboration Tools
Reference to LPI objectives
Open Source Essentials version 1.0, Exam 050, Objective 056.3
Weight2
Key knowledge areas• Understanding common tools for communication• Understanding common ways to capture and secure knowledge• Understanding common tools for information management and publication• Understanding common types of documentation• Understanding common collaboration features of source code management platforms• Understanding the concepts of stand-alone, federated and centralized managed applications
and platforms
Partial list of the used files, terms and utilities• Instant messengers• Chat platforms• Mailing lists• Newsletters• Issue trackers and bug trackers• Bug reports• Merge requests and pull requests• Helpdesk and ticketing systems
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Open Source Essentials (Version 1.0) | 056.3 Communication and Collaboration Tools• Wikis• Document Management Systems (DMS)• Documentation websites• Product websites• Content Management Systems (CMS)• Architecture documentation• User documentation• Administrator documentation• Developer documentation

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Lesson 1
Certificate:Open Source Essentials

Version:

1.0

Topic:

056 Collaboration and Communication

Objective:

056.3 Communication and Collaboration Tools

Lesson:1 of 1Introduction
Many open source projects have active participants worldwide. Collaboration mostly happens in“virtual space,” and the people involved are often distributed across countries, continents, andtimezones. Furthermore, they usually speak different native languages. This means you can belocated anywhere in the world to make a contribution to an open source project, no matter yourcountry or language!
While this diversity makes contributing to an open source project extremely rewarding, as you
can widen your scope and learn a lot, at the same time it can make communication andcoordination quite challenging. Efficient and effective communication is key to the success andsustainability of any open source project. To ensure good communication, open source projects
have created structures and use a variety of tools that help to make contributions easy and thecooperation more effective.
Another challenge is that open source projects, often driven mostly by volunteers, face somefluctuation in participation. People’s lives and hobbies change, and some might lose interest or
just run out of time. You might contribute to an open source project for years, but when you
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volunteer.
Therefore, in addition to providing efficient means of communication via proper tooling, open
source projects need to ensure the preservation and sharing of knowledge to avoid “reinventing
the wheel.” Information preservation also helps contributors learn from the past mistakes ofother contributors and avoid making the same errors.
This lesson presents common tools for cooperating in an open source project and introduces you
to ways of communicating in an international community. You’ll discover that there’s an easy way
for everyone to make their first contribution!
As an example of communications and information sharing, we will look at the LibreOffice.
LibreOffice is an open source office productivity suite that is available in more than one hundred
languages. Its end users range from the casual home user to large governments and corporations.
Likewise, there’s a wide range of contributors — not only developers, but also localizers,
documentation authors, marketing people, quality assurance engineers, infrastructure
administrators, graphics and UX designers, and many, many more.
In other words: For LibreOffice, as for many other open source projects, you can bring in yourskill and talent in the area you are comfortable with. You don’t necessarily need to be atechnically trained person or a developer — you can bring in your creativity and artistic talent or
your language skills as well. The project has also launched a website that shows the various areasof contributions: https://whatcanidoforlibreoffice.org. So LibreOffice will nicely illustrate many
aspects of community work.

Ways to Communicate
Before looking into the details of communication tools, it is important to understand how
communication works in general, as these considerations inform the choices of tools.
Open source projects enjoy two different major ways to communicate. With synchronous
communication, people communicate at the same time. Examples include of course directconversations, but also video conferences or phone calls. With asynchronous communication,
people communicate at different times. Examples are email and SMS, but also a postal letter or atelefax.
This distinction is not always easy to make, however. As one example, a messenger application ona mobile phone like WhatsApp, Telegram, Signal, or Element technically is an asynchronous way
to communicate. If, however, both conversation partners are online at the very same time andreply instantly, they enter a direct conversation.
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what expectations they have. Each task might require a different set of communication tools. The
following sections will explain these ideas in detail.

Synchronous Communication
Synchronous communication is a very effective but also very demanding way to communicate. It
brings people together at the same time in the same physical or virtual space.
A direct meeting is ideal for talking things through interactively instead of sending long email
messages that come with the risk of misunderstandings. Imagine you want to learn more about an
open source project and get to know the people from the community. Email messages andwebsites can help make an introduction and have a lower barrier to entry, but a truly meaningful
first impression is made when you can actually talk to someone in person — it’s these directinteractions that usually fascinate people about an open source project and make them want tocontribute.
Apart from getting to know each other, synchronous meetings are also great to talk things throughinteractively, e.g. in case of conflicts or problems, or when you have to share a negative message.
The downside is that international projects face a challenge that technology can’t overcome:timezones. If you have contributors on different continents, it will be very hard to find suitable
meeting slots that work for everyone. Someone in Australia might just be waking up whensomeone in Europe is close to calling it a day. As an additional challenge, some people can work
only at night or weekends, while others prefer office hours during business days.
Additionally, English is not a language everyone speaks fluently, and there are no widely
accessible live translation tools available yet, which brings an additional barrier.
Even so, video conferences are one of the most frequent tools of communication in open source
projects. The LibreOffice project, which serves as an example for this lesson, has regular online
meetings for its community, e.g. for developers, marketing, infrastructure, quality assurance, user
experience, and design.

Asynchronous Communication
Asynchronous communication lets you participate in the discussion at a time and speed that isconvenient for you. The most known example is probably an email message: You can reply to amessage whenever you prefer, whether it’s the next minute, the next day, or the next hour.
For asynchronous communication, the content usually is in writing, which additionally opens up
the possibility of machine translation. This helps you to read and understand messages written ina language different from your native language, and you can even translate back your reply.

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Additionally, content that is already written down makes it much easier to retain knowledge andproduce documentation. Imagine you want to write a support document about how to use a
specific feature of a software. If you explain it to a user over the phone, it will be much harder toturn your speech into a proper documentation page than when you explain the procedure in
written text.

Internal Versus External Communication
Last but not least, communication also depends on the intended recipients, i.e. whether it isinternal or external. You will write an internal, technical note to the system administrators
differently from how you write a press release that gets sent to hundreds of journalists. Keep inmind, however, that due to the nature of an open source project, communication that might not
be explicitly intended for a public audience will nevertheless be publicly visible, for example inmailing list archives (in the case of LibreOffice, it’s https://listarchives.documentfoundation.org/).

Tools for Communication
With these different general aspects of communication in mind, you will learn in the following
sections about several tools for communication that are commonly used in an open source project.

Email, Mailing Lists, and Newsletters
One of the first tools you will encounter when you participate in an open source project is the“classic” email. Many projects run mailing lists, which are essentially distribution lists for email:With one email message, you can reach hundreds or even thousands of subscribers who areinterested in particular topics.
Mailing lists are among the oldest known tools in any open source project and are used for
coordination internal to the project as well for interacting with users. If you have a question about
the software, or want to report an error in the program, chances are high that there is a mailinglist that allows you to do that. The LibreOffice community, for example, offers a variety ofinternational and local mailing lists for various topics (https://www.libreoffice.org/get-help/
mailing-lists/), ranging from user support to developer discussions and infrastructure
coordination (LibreOffice mailing lists web page).

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Figure 17. LibreOffice mailing lists web page

Every message sent is usually also stored in a public mailing list archive for future reference. Oncesent out, a message cannot be easily deleted. A common phrase goes, “The internet never forgets.”
Therefore it is advisable to be careful what you write, because you probably can’t take it back. For
example, some people have their private address or phone number in the signature, or send
confidential documents as attachments, which you should carefully avoid.
One disadvantage of mailing lists is that managing them in your mail program is not always
straightforward. You will want to create so-called filters based on specific elements of themessage, e.g. a prefix in the subject line. The subtleties of managing large quantities of email canbe a barrier for unexperienced users — especially if your message is a one-off. Therefore, more
and more projects migrate to discussions forums, about which you will soon learn.
A special form of mailing list is a newsletter. If you want to stay up to date about the latest project
developments and get informed about new software releases, you can subscribe to the newsletterand get an email message when something important happens.

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Discussion Forums
Apart from the overhead of managing mailing lists in your email client, another downside ofemail is that more and more people, especially the younger generation, is not so much into emailcommunication anymore. For this and other reasons, more and more open source projects movetheir communication to discussion forums. The general idea is very comparable to email: Eachforum has various categories with specific topics to engage in discussion, so-called threads.
Similar to email, on a forum you can get in touch with the open source project and coordinate
activities, make suggestions for the direction of the project, and report errors as an end user.
Everything posted to a forum is usually visible to the general public, just as in a mailing list; but
unlike there, depending on the forum’s configuration, contents can also be edited or deleted later.
The usability of forums is, especially for inexperienced users, often better than mailing lists. The
LibreOffice project began converting several of its mailing lists to forums(https://community.documentfoundation.org/) and has since seen an increase in participation in
the discussion.

Figure 18. LibreOffice forums web page

Instant Messages and Chat Platforms
Another way to get in touch with an open source community is through instant messages and chatplatforms. With the rise of popular tools like WhatsApp, Telegram, Signal, and Matrix, nearly
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everyone has already installed one of these popular applications on their devices, which makes
the entry barrier much lower. Instant messages are also much more popular with the younger
generation than email or forums. It therefore comes as no surprise that many open source
projects these days adopt them.
Participants in chats type messages that are sent to all other participants, similar to email.
Depending on the chat platform, a message can be enriched with formatting, graphics, andattachments.
Structurally, message apps are organized similar to a forum or email. Several groups or channels
are available, so you can join discussions on topics you are interested in. Messages can usually beedited or deleted, and often there are also announcement-only channels that have a function
similar to email newsletters.
One drawback of instant messenger apps is that people usually install them on their phones, sothey receive notifications of every message sent. This quickly can turn into information overflow
or “alert fatigue.” With proper configuration, however, these notifications can be kept undercontrol.
Another downside is that many messenger apps are proprietary and in the hands of one vendor.
This makes preserving knowledge for the long term more complicated, if data is not freely
accessible.

Stand-Alone, Federated, and Centralized Communications
Open source projects work in the open, based on open standards and open tools. Therefore it iscritical to understand how the various tools are designed with regard to interoperability. The
options can be split into three main categories.
A stand-alone platform runs in an isolated manner for one community. Examples are forums or
wikis, which are usually not connected with instances of other projects.
Decentralized or federated systems run individually for each community, but can connect to eachother. One example is email, because a local email server can send email to any other email serverin the world. Other examples include Nextcloud and ownCloud, which can “federate” file shareswith other servers, and the Element messenger service, with which you can communicate withusers of other servers. The same principles apply to the Mastodon social network.
Both stand-alone and distributed platforms have one huge advantage: The open source project
stays in full control over all content and functionality. All the knowledge stored in such a systemremains the property of the open source community and is not subject to third parties.

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A centralized system, on the other hand, is run by one provider and does not interact with third
parties. Classical examples are social networks like Facebook or Instagram, or messenger apps
like WhatsApp or Telegram. All content is stored on the external provider’s servers and is subject
to their terms and conditions.
If you are active in an open source community, you likely get in touch using all three of these
options. Centralized systems are great for reaching out to people, as they often are popular andhave a large user base. For actual work in the project, however, a federated or stand-alone system
under the control of the community is best.

Tools for Collaboration
The distinction between tools for communication and tools for collaboration is not always
straightforward. For the purpose of this lesson, the main goal of communication tools is to enablegeneral communication between diverse participants, whereas the main goal of collaboration
tools is to help people work together.
Proper collaboration tools allow file storage, real-time collaboration on documents, tracking of
document versions and changes between software releases, and much more. While email orforums can serve as general-purpose storage, specialized tools make knowledge more easily
accessible and collaboration much more effective.
In other words, these are specialized tools for specific tasks. If you want to contribute to an open
source project, you will encounter them very soon.

Wikis
One of the oldest and most popular tools for collaboration is a wiki. Made famous especially by
Wikipedia, a wiki allows users to work together on a website that is compiled of several
documents or “articles.” They can be grouped in various categories, filtered by language, andcontain formatting, spreadsheets, and images.
Wikis are often used as a knowledge base where everybody can contribute. If you want tocontribute content to an open source project, participating in their wiki is one of the moststraightforward ways. You can take existing content and translate it into your native language,
edit and update existing articles, or create new content. In the wiki of the LibreOffice project(https://wiki.documentfoundation.org), you can find marketing material, board meeting minutes,
installation instructions, and conference planning, all in a variety of languages (LibreOffice Wiki).

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Figure 19. LibreOffice Wiki

Many open source projects also host their documentation and their program’s integrated help
system in a wiki. Additionally, old versions of a page — called revisions — are archived for futurereference.
Although wikis can also store project files, there are better tools for this purpose, as you will learn
in this lesson.

Bug and Issue Trackers
Another frequently used tool in an open source project are bug trackers, also called issue trackers.
If you discover a problem in the software, or want to suggest a new feature, you might think ofjust sending an email message about it. With a dedicated tool like a bug tracker, however, you canprovide all required information and steps to reproduce a problem in a structured way, whichmakes it easier for developers to reproduce the issue. Such a structured report is called a bug
report.
In addition, the information is not lost and the project doesn’t forget about the issue; it can assign
it to the right person and see how many bugs are being processed or fixed.
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Figure 20. LibreOffice bug tracker

Helpdesks and Ticketing Systems
A very similar tool is a helpdesk or ticketing system. Its focus is less on reporting software
problems, but rather to help users with all kind of issues and requests, such as for the project’s
website.
The classic helpdesk is a customer service hotline. A customer calls and reports a problem, which
is turned into a ticket. The workflow of a helpdesk system usually revolves around priorities,
escalation levels, and response time.
Not all open source communities provide such a system, but many commercial companies do. For
the LibreOffice project, for instance, there is a ticketing system for infrastructure to reportproblems with servers and web services.

Content Management System (CMS)
Another important tool for collaboration is a content management system (CMS). As the namesuggests, it helps to manage the content, most notably for websites. If you want to contribute to
the content or the design of a project’s website, making yourself familiar with their CMS is the way
to go.
CMS systems, similar to wikis, help to structure content in categories and languages. They often
provide a WYSIWYG (“what you see is what you get”) editor and embed everything in a proper
template: Titles, headings, page layout, and menu entries are done automatically, so you can focus
fully on the content. Additionally, in case of a page redesign, the content will not disappear, butwill be adapted to the new template.

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Document Management System (DMS)
A document management system is not to be confused with a content management system. Whilea CMS is designed to show content in a predefined template, like for presenting a website, a DMS
is used for the management of documents such as contracts, invoices, receipts, email messages,
and all other sorts of correspondence.
Another difference is that a CMS is often used for public presentation, while a DMS is mostly used
to manage internal documents that are not intended for the general public.
As a contributor to an open source project, you are less likely to encounter the document
management system, as that is often reserved for specific roles such aas accounting or legal.

Source Code Management (SCM)
If you are a developer in an open source project, one of the key tools you will soon run into is thesource code management platform. Comparable to a wiki for documentation authors, SCMs areused by software developers to work together on the code.
Historical SCMs include CVS and Subversion, but nowadays Git is mostly used including by the
LibreOffice community (https://git.libreoffice.org/). These tools are available on the command line,
but there are also graphical interfaces available to make interaction easier, especially for
beginners.
Source code management platforms track different versions of each file, handle changes and edits
to the code, record who made which change, and ideally give a full history of the software’s
development.
Developers can “check out” a specific state of the software, locally work on it, e.g. by fixing a bug
or implementing a new feature, and then request that this change be added to the maindevelopment line of the software by means of a so-called merge request, also known as a pull
request. Accepting the merge or pull request “merges” the changes done by one author with themain code.
There are centralized platforms (GitHub and GitLab) that integrate SCM with wikis, issue tracking,and other collaborative tools.
Source code management platforms are not strictly limited to program code. As one example, thisvery lesson was worked on collaboratively in a Git repository!

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Documentation
Key to the success of every open source project is proper documentation, ideally in several
languages. The LibreOffice project provides up-to-date books, guidelines, and reference cards(https://documentation.libreoffice.org) for its software, as well as individual help pages on specificfunctions (https://help.libreoffice.org).
In general, there are different kinds of documentation, which we’ll discuss in the following
sections.

User Documentation
Best known is the documentation for end users, which explains how to use the software. If you
don’t know about a feature or function in the program, the documentation — which can range
from individual help pages to a complete book — is your first point of reference.
The documentation website, where the use of the software is explained, is often one of the mostfrequented websites next to the product website, which presents an overview of the software andits community.

Administrator Documentation
For use in larger environments, like deployments in a company, administrator documentation
provides all relevant information for deploying the software on a larger scale. This includes
connecting to user databases and file storage, centralized configuration management, andhandling updates.

Developer and Architecture Documentation
Another category of documentation targets developers and is called developer documentation orarchitecture documentation. If you are a developer and want to contribute to the code of aprogram, this documentation tells you about the software architecture, the coding standards, andthe tools and workflows used to work on the software.
The LibreOffice project has published a developers guide in its wiki to help interested developers
join the community (https://wiki.documentfoundation.org/Documentation/DevGuide).

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Guided Exercises
1. Why do open source projects in particular have to take care of proper tools for communicationand collaboration?

2. Name one example each for synchronous and asynchronous communication.

3. What is a disadvantage of messenger apps and how can this be avoided?

4. Name two functions of a wiki.

5. What is the difference between a bug tracker and a helpdesk system?

6. What is the difference between a content management and a document management system?

7. What is the advantage of stand-alone or federated systems over centralized systems?

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Explorational Exercises
1. What is one of the main differences between a local sports club and an international open
source project?

2. Why can contributing to an open source project be particularly rewarding?

3. Which bug tracking software does the Ubuntu project use?

4. What is the name of the website for the Linux kernel mailing lists?

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Summary
In this lesson, you’ve learned about a variety of tools used for communicating and collaborating inan open source project. You’ve heard the difference between synchronous and asynchronous
communication and between decentralized, centralized, and stand-alone tools. You also learned
why specific tools can be helpful for specific tasks to make contributing to an open source project
fun and rewarding.

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Answers to Guided Exercises
1. Why do open source projects in particular have to take care of proper tools for communicationand collaboration?
On one hand, working together in a worldwide distributed group has its set of challenges,
which proper tools can help to address. On the other hand, volunteers might not stayindefinitely, so retaining and sharing knowledge is another important aspect in the use ofcommunication and collaboration tools. Making contributions easy helps the sustainability of a
project.
2. Name one example each for synchronous and asynchronous communication.
Synchronous communication could be a direct conversation, a phone call, or a videoconference. Examples of asynchronous communication include email, SMS, postal letters, andfaxes.
3. What is a disadvantage of messenger apps and how can this be avoided?
When installed on the phone, you might receive many notifications, one for each new message.
Proper configuration can help avoid this. Another disadvantage is that many messenger apps
are run by proprietary vendors.
4. Name two functions of a wiki.
Collaborative editing and translation of articles.
5. What is the difference between a bug tracker and a helpdesk system?
A bug tracker is a specialized software tool to report bugs or request features in software. A
helpdesk system focuses on supporting inquiries and managing all kind of issues and requests,
e.g. on the website.
6. What is the difference between a content management and a document management system?
A CMS is used for presenting content in a specific way or template, mostly publicly. A DMS isused to store existing correspondence, mostly internally.
7. What is the advantage of stand-alone or federated systems over centralized systems?
A centralized system is under the control of one external provider. All content is stored on theexternal provider’s servers and subject to their terms and conditions.

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Answers to Explorational Exercises
1. What is one of the main differences between a local sports club and an international open
source project?
Open source projects are not bound to a specific language or location. Contributors can live on
different countries and continents, have different native languages and even live in different
timezones. Most of the activity carried out in an open source project happens virtually, not in
person.
2. Why can contributing to an open source project be particularly rewarding?
Many open source projects have a diverse group of people. By collaborating with them, you canlearn from them, discover new things, and widen your scope.
3. Which bug tracking software does the Ubuntu project use?
Launchpad
4. What is the name of the website for the Linux kernel mailing lists?
https://lkml.org/

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Open Source Essentials (Version 1.0) | Imprint

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PDF generated: 2024-07-26
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