# Ivar Jacobson

Ivar Hjalmar Jacobson (born 1939) is a Swedish computer scientist and software engineer, known as major contributor to UML, Objectory, RUP, aspect-oriented software development and Essence.

## Quotes

* The Uniﬁed Modeling Language (UML) is a general-purpose visual modeling language that is used to specify, visualize, construct, and document the artifacts of a software system. It captures decisions and understanding about systems that must be constructed. It is used to understand, design, browse, conﬁgure, maintain, and control information about such systems. It is intended for use with all development methods, lifecycle stages, application domains, and media. The modeling language is intended to unify past experience about modeling techniques and to incorporate current software best practices into a standard approach. UML includes semantic concepts, notation, and guidelines. It has static, dynamic, environmental, and organizational parts. It is intended to be supported by interactive visual modeling tools that have code generators and report writers. The UML speciﬁcation does not deﬁne a standard process but is intended to be useful with an iterative development process. It is intended to support most existing object-oriented development processes.
** James Rumbaugh, Ivar Jacobson, & Grady Booch (1999) The Unified Modeling Language Reference Manual. p. 1.

### Object-Oriented Software Engineering: A Use Case Driven Approach (1992)

Ivar Jacobson, Magnus Christerson, Patrik Jonsson & Gunnar Overgaard 1992. Object-Oriented Software Engineering: A Use Case Driven Approach (ACM Press). Addison-Wesley, 1992, ISBN 0-201-54435-0.
* People regard their environment in terms of objects. Therefore it is simple to think in the same way when it comes to designing a model.
** p. 42; cited in: Sten Carlsson and Benneth Christiansson. (1999) "The Concept of Object and its Relation to Human Thinking: Some Misunderstandings Concerning the Connection between Object-Orientation and Human Thinking." Informatica, Lith. Acad. Sci. 10.2. p. 147-160.
* When a user uses the system, she or he will perform a behaviorally related sequence of transactions in a dialogue with the system. We call such a special sequence a use case.
** p. 127; as cited in: Journal of Object-oriented Programming Vol 10, Nr 2-9. p. 32.
* The control objects model functionality that is not naturally tied to any other object... We do not believe that the best (most stable) systems are built by only using objects that correspond to real-life entities, something that many other object-oriented analysis and design techniques claim... Behavior that we place in control objects will, in other methods, be distributed over several other objects, making it hard to change this behavior.
** p. 133 as cited in: "Object Oriented Software Engineering: A Use Case Driven Approach Ivar Jacobson, et al. (1992)", Book review by Ted Felix on tedfelix.com, 2006.
* A use case is a complete course of events in the system, seen from a user’s perspective.
** p. 157.
* The analysis model will not be a reflection of what the problem domain looks like... The reason is simply to get a more maintainable structure where changes will be local and thus manageable. We thus do not model reality as it is, as object orientation is often said to do, but we model the reality as we want to see it and to highlight what is important in our application.
** p. 185: cited in: "Object Oriented Software Engineering: A Use Case Driven Approach Ivar Jacobson, et al. (1992)", Book review by Ted Felix on tedfelix.com, 2006.

## Quotes about Ivar Jacobson

* The key books about object-oriented graphical modeling languages appeared between 1988 and 1992. Leading figures included Grady Booch [Booch,OOAD]; Peter Coad [Coad, OOA], [Coad, OOD]; Ivar Jacobson (Objectory) [Jacobson, OOSE]; Jim Odell [Odell]; Jim Rumbaugh (OMT) [Rumbaugh, insights], [Rumbaugh, OMT]; Sally Shlaer and Steve Mellor [Shlaer and Mellor, data], [Shlaer and Mellor, states] ; and Rebecca Wirfs-Brock (Responsibility Driven Design) [Wirfs-Brock].
** Martin Fowler (2004) A Brief Guide to the Standard Object Modeling Language. p. 7.