VB .Net: For Experienced Programmers
Authors: Harvey M. Deitel, Paul J. Deitel
Venue:  (2002)

From the Book:PrefaceLive in fragments no longer. Only connect.Edward Morgan ForsterWe wove a web in childhood,A web of sunny air.Charlotte BronteWelcome to Visual Basic .NET and the world of Windows, Internet, and World Wide Web programming with Visual Studio .NET and the .NET platform! This book is the third in the new Deitel Developer Series, which presents leading-edge computing technologies to software developers and IT professionals.Visual Basic .NET was created from Visual Basic 6.0 by Microsoft expressly for its .NET platform. Visual Basic .NET provides the features that are most important to programmers, such as object-oriented programming, graphics, graphical-user-interface (GUI) components, exception handling, multithreading, multimedia (audio, images, animation and video), file processing, prepackaged data structures, database processing, Internet and World-Wide-Web-based multi-tier application development, networking, Web services and distributed computing. The language is appropriate for implementing Internet- and World-Wide-Web-based applications that integrate seamlessly with Windows-based applications.The .NET platform offers powerful capabilities for software development and deployment, including language and platform independence. For example, developers writing code in any (or several) of the .NET languages (such as Visual Basic .NET, C# and Visual C++ .NET) can contribute components to the same software product. In addition to providing language independence, .NET extends program portability by enabling .NET applicationsto reside on, and communicate across, multiple platforms. This facilitates the creation and use of Web services, which are applications that expose functionality to clients over the Internet.The .NET platform enables Web-based applications to be distributed to consumer-electronic devices, such as wireless phones and personal digital assistants (PDAs), as well as to desktop computers. The capabilities that Microsoft has incorporated into the .NET platform increase programmer productivity and decrease development time.Who Should Read This BookDeitel Associates, Inc. currently has two Visual Basic .NET publications, intended for different audiences. We provide information on www.deitel.com, here and inside this book's back cover to help you determine which publication is best for you.Our first Visual Basic .NET book, Visual Basic .NET How to Program, Second Edition, was published as part of our How to Program Series, for college and university students. It provides a comprehensive treatment of Visual Basic .NET and includes learning aids and extensive ancillary support. Visual Basic .NET How to Program, Second Edition assumes that the reader has little or no programming experience. Early chapters focus on fundamental programming principles. The book builds on this to create increasingly complex and sophisticated programs that demonstrate how to use Visual Basic .NET to create graphical user interfaces, networking applications, multithreaded applications, Web-based applications and more. We encourage professors and professionals to consider the The Complete Visual Basic .NET Training Course. This package includes Visual Basic .NET How to Program, Second Edition, as well as the Visual Basic .NET Multimedia Cyber Classroom, Second Edition, an interactive multimedia CD-ROM that provides extensive e-Learning features. The Complete Visual Basic .NET Training Course, Second Edition and Visual Basic .NET Multimedia Cyber Classroom, Second Edition are discussed in detail later in this Preface.This book, Visual Basic .NET for Experienced Programmers, is part of the new Deitel Developer Series, intended for professional software developers-from novices through experienced programmers. This publication is a part of the For Experienced Programmers subseries, designed for the experienced software developer who wants a deep treatment of a new technology with minimal, if any, introductory material. Visual Basic .NET for Experienced Programmers provides a brief introduction to programming principles in general and to Visual Basic .NET fundamentals, then delves deeply into more sophisticated topics, such as Web development and distributed computing. There is considerable overlap between this book and Visual Basic .NET How to Program, Second Edition.A third publication, ASP .NET with Visual Basic .NET for Experienced Programmers, is forthcoming. This book was originally titled Advanced Visual Basic .NET for Experienced Programmers.Each of our Visual Basic .NET books presents many complete, working Visual Basic .NET programs and depicts their inputs and outputs in actual screen shots of running programs. This is our signature Live-Code approachwe present concepts in the context of complete working programs. Each book's source code is available free for download at www.deitel.com.Please examine both the Deitel Developer Series professional books and the How to Program Series textbooks to determine which best suits your needs. Visual Basic .NET for Experienced Programmers is derived from Visual Basic .NET How to Program, Second Edition. Depending on your particular needs, you should purchase either this book or Visual Basic .NET How to Program, Second Edition.This book was written after Visual Basic .NET How to Program, Second Edition. We added to this Deitel Developer Series book a chapter on the new Microsoft Mobile Internet Toolkit for our readers who wish to develop wireless Internet applications for wireless phones, pagers and PDAs. This material will be added to the third edition of Visual Basic .NET How to Program.For a detailed listing of Deitel products and services, please see the "advertorial" pages at the back of this book and visit www.deitel.com. Readers may also want to register for our new Deitel? Buzz Online e-mail newsletter (www.deitel.net/newsletter/subscribe.html), which provides information about our publications, company announcements, links to informative technical articles, programming tips, teaching tips, challenges and anecdotes.As you proceed, if you would like to communicate with us, please send an e-mail to deitel@deitel.com-we always respond promptly. Please check our Web sites, www.deitel.com, www.prenhall.com/deitel and www.InformIT.com/deitel for frequent updates, errata, FAQs, etc. When sending an e-mail, please include the book's title and edition number. We sincerely hope that you enjoy learning Visual Basic .NET with our publications.Features of Visual Basic .NET for Experienced ProgrammersThis edition contains many features, including: Syntax Highlighting. This book uses five-way syntax highlighting to emphasize Visual Basic .NET programming elements in a manner similar to that of Visual Studio .NET. Our syntax-highlighting conventions are as follows: comments keywords literal values errors and ASP .NET directives text, class, method and variable names "Code Washing." This is our term for the process we use to format the book's programs so that they have a carefully commented, open layout. The code is grouped into small, well-documented pieces. This greatly improves code readability-an especially important goal for us, considering that this book contains approximately 20,300 lines of code in 192 complete Live-Code programs. Web Forms, Web Controls, and ASP .NET. The .NET platform enables developers to create robust, scalable Web-based applications. Microsoft's .NET server-side technology, Active Server Pages (ASP) .NET, allows programmers to build Web documents that respond to client requests. To enable interactive Web pages, server-side programs process information users input into HTML forms. ASP .NET is a significant departure from ASP 3.0, allowing developers to program Web-based applications using .NET's powerful object-oriented languages such as Visual Basic .NET and C#, rather than using only scripting languages. ASP .NET also provides enhanced visual programming capabilities, similar to those used in building Windows forms for desktop programs. Programmers can create Web pages visually, by controls onto Web forms. Chapter 17, ASP .NET, Web Forms and Web Controls, introduces these powerful technologies. Web Services and ASP .NET. Microsoft's .NET strategy embraces the Internet and Web as integral to software development and deployment. Web services technology enables information sharing, e-commerce and other interactions using standard Internet protocols and technologies, such as Hypertext Transfer Protocol (HTTP), Extensible Markup Language (XML) and Simple Object Access Protocol (SOAP). Web services enable programmers to package application functionality in a manner that turns the Web into a library of reusable software components. In Chapter 18, ASP .NET and Web Services, we present a Web service that allows users to manipulate "huge integers"-integers too large to be contained in Visual Basic .NET's built-in data types. In this example, a user enters two huge integers and presses buttons to invoke Web services that add, subtract and compare the two integers. Object-Oriented Programming. Object-oriented programming is the most widely employed technique for developing robust, reusable software. This text offers a rich treatment of Visual Basic .NET's object-oriented programming features. Chapter 5, Object-Based Programming, introduces how to create classes and objects. These concepts are extended in Chapter 6, Object-Oriented Programming: Inheritance, which discusses how programmers can create powerful new classes quickly by "absorbing" the capabilities of existing classes. Chapter 7, Object-Oriented Programming: Polymorphism, familiarizes the reader with the crucial concepts of polymorphism, abstract classes, concrete classes and interface which facilitate powerful manipulations among objects belonging to an inheritance hierarchy. XML. Use of Extensible Markup Language (XML) is exploding in the software-development industry, in the e-business and e-commerce communities, and is pervasive throughout the .NET platform. Because XML is a platform-independent technology for describing data and for creating markup languages, XML's data portability integrates well with Visual Basic .NET-based portable applications and services. Chapter 15, Extensible Markup Language (XML), introduces XML. In this chapter, we introduce basic XML markup and discuss the technologies such as DTDs and Schema, which are used to validate XML documents' contents. We also explain how to manipulate XML documents programmatically using the Document Object Model (DOM) and how to transform XML documents into other types of documents via Extensible Stylesheet Language Transformations (XSLT). Multithreading. Computers enable programmers to perform many tasks in parallel (i.e., concurrently), such as printing documents, downloading files from a network and surfing the Web. Multithreading is the technology through which programmers can develop applications that perform concurrent tasks. Historically, a computer has contained a single, expensive processor, which its operating system would share among all applications. Today, processors are becoming increasingly inexpensive, making it possible to build affordable computers with many processors working in parallel-such computers are called multiprocessors. Multithreading is effective on both single-processor and multiprocessor systems. .NET's multithreading capabilities make the platform an related technologies better prepared to handle today's sophisticated multimedia-intensive, database-intensive, network-based, multiprocessor-based, distributed applications. Chapter 11, Multithreading, introduces this powerful capability. ADO .NET. Databases store vast amounts of information that individuals and organizations must access to conduct business. As an evolution of Microsoft's ActiveX Data Objects (ADO) technology, ADO .NET represents a new approach for building applications that interact with databases. ADO .NET uses XML and an enhanced object model to provide developers with the tools they need to access and manipulate databases for large-scale, extensible, mission-critical multi-tier applications. Chapter 16, Database, SQL and ADO .NET, introduces the capabilities of ADO .NET and the Structured Query Language (SQL) to manipulate databases. Wireless Development. By some estimates, about a billion people worldwide are using mobile devices, such as wireless phones and PDAs, and this number is increasing rapidly. To simplify the creation of Web content for mobile devices, Microsoft provides the Mobile Internet Toolkit (MIT). The MIT, which is built on ASP .NET, allows wireless content to be created using Visual Studio .NET's object-oriented languages. One program can be created that will be compatible with a variety of devices and able to display different content based on the type of device (e.g., a wireless phone versus a PDA). Chapter 21, Mobile Internet Toolkit, introduces wireless Web application development. Visual Studio .NET Debugger. Debuggers help programmers find and correct logic errors in program code. In Appendix B, Studio .NET Debugger, we explain how to use key debugger features, such as setting "breakpoints" and "watches," stepping into and out of methods, and examining the method call stack. Unicode. As computer systems evolved worldwide, computer vendors developed numeric representations of character sets and special symbols for the local languages spoken in different countries. In some cases, different representations were developed for the same languages. Such disparate character sets hindered communication among computer systems. Visual Basic .NET supports the Unicode Standard (maintained by a non-profit organization called the Unicode Consortium), which maintains a single character set that specifies unique numeric values for characters and special symbols in most of the world's languages. Appendix D, Unicode, discusses the standard, overviews the Unicode Consortium Web site, www.unicode.org and presents a Visual Basic .NET application that displays "Welcome to Unicode!" in several languages.Pedagogic ApproachVisual Basic .NET for Experienced Programmers contains a rich collection of examples that have been tested on Windows 2000 and Windows XP. The book concentrates on the principles of good software engineering and stresses program clarity. We are educators who teach edge-of-the-practice topics in industry classrooms worldwide. We avoid arcane terminology and syntax specifications in favor of teaching by example. The text emphasizes good pedagogy. We use fonts to distinguish between Visual Studio .NET's Integrated Development Environment (IDE) features (such as menu names and menu items) and other elements that appear in the IDE. Our convention to emphasize IDE features in a sans-serif bold Helvetica font (e.g., Project menu) and to emphasize program text in a serif bold Courier font (e.g., Dim x As Integer).Live-Code Teaching ApproachVisual Basic .NET for Experienced Programmers is loaded with numerous Live-Code examples. This style exemplifies the way we teach and write about programming and is the focus of our multimedia Cyber Classrooms and Web-based training courses as well. Each new concept is presented in the context of a complete, working example that is followed by one or more windows showing the program's input/output dialog. We call this method of teaching and writing the Live-Code Approach. We use programming languages to teach programming languages. Reading the examples in the text is much like entering and running them on a computer. Readers have the option of downloading all of the book's code examples from www.deitel.com, under the Downloads/Resources link. Other links provide errata and answers to frequently asked questions.World Wide Web AccessAll of the source code for the examples in Visual Basic .NET for Experienced Programmers (and our other publications) is available on the Internet as downloads from the following Web sites:www.deitel.comwww.prenhall.com/deitelRegistration is quick and easy and these downloads are free. We suggest downloading all the examples, then running each program as you read the corresponding portion of the book. Make changes to the examples and immediately see the effects of those changes-this is a great way to improve your programming skills. Any instructions for running the examples assumes that the user is running Windows 2000 or Windows XP and is using Microsoft's Internet Information Services (IIS). Additional setup instructions for IIS and other software can be found at our Web sites along with the examples. Note: This is copyrighted material. Feel free to use it as you study, but you may not republish any portion of it in any form without explicit permission from Prentice Hall and the authors.Visual Studio .NET belongs to a family of products that are available for purchase and download from Microsoft. Visual Studio .NET, which includes Visual Basic .NET, comes in four different editions-Academic, Professional, Enterprise Developer and Enterprise Architect. Visual Studio .NET Academic contains Visual Studio .NET Professional's features in addition to features designed for students and professors (e.g., an Assignment Manager that documents assignment submission, Application Publishing Tools that aid in the notification of assignments, code samples and more).Microsoft also offers stand-alone products (Visual C# .NET Standard, Visual C++ .NET Standard and Visual Basic .NET Standard) for various .NET-languages. Each product provides an integrated development environment (similar to Visual Studio .NET) and a compiler. Visit msdn.microsoft.com/vstudio/howtobuy for descriptions and ordering information.ObjectivesEach chapter begins with objectives that inform readers of what to expect and gives them an opportunity, after reading the chapter, to determine whether they have met the intended goals.QuotationsThe chapter objectives are followed by sets of quotations. Some are humorous, some are philosophical and some offer interesting insights. We have found that readers enjoy relating the quotations to the chapter material. Many of the quotations are worth a "second look" after you read each chapter.OutlineThe chapter outline enables readers to approach the material in top-down fashion. Along with the chapter objectives, the outline helps users anticipate topics and set a comfortable and effective learning pace. Approximately 20,300 Lines of Code in 192 Example Programs (with Program Outputs) We present Visual Basic .NET features in the context of complete, working Visual Basic .NET programs. The programs range in size from just a few lines of code to substantial examples containing hundreds of lines of code. All examples are available as downloads from our Web site, www.deitel.com.559 Illustrations/FiguresAn abundance of charts, line drawings and program outputs is included.319 Programming TipsWe have included programming tips to help readers focus on important aspects of program development. We highlight hundreds of these tips in the form of Good Programming Practices, Common Programming Errors, Testing and Debugging Tips, Performance Tips, Portability Tips, Software Engineering Observations and Look-and-Feel Observations. These tips and practices represent the best the authors have gleaned from many decades of programming and teaching experience. One of our customers-a mathematics major-told us that she feels this approach is like the highlighting of axioms, theorems and corollaries in mathematics books; it provides a foundation on which to build good software.32 Good Programming PracticesGood Programming Practices are tips that call attention to techniques that will help developers produce programs that are clearer, more understandable and more maintainable.100 Common Programming ErrorsDevelopers learning a language tend to make certain kinds of errors frequently. Pointing out these Common Programming Errors reduces the likelihood that readers will make the same mistakes.34 Testing and Debugging TipsWhen we first designed this "tip type," we thought the tips would contain suggestions strictly for exposing bugs and removing them from programs. In fact, many of the tips describe aspects of Visual Basic .NET that prevent "bugs" from getting into programs in the first place, thus simplifying the testing and debugging processes.39 Performance TipsDevelopers like to "turbo charge" their programs. We have included 39 Performance Tips that highlight opportunities for improving program performance-making programs run faster or minimizing the amount of memory that they occupy.11 Portability TipsWe include Portability Tips to help developers write portable code and to provide insights on how Visual Basic .NET achieves its high degree of portability.86 Software Engineering ObservationsThe object-oriented programming paradigm necessitates a complete rethinking of the way we build software systems. Visual Basic .NET is an effective language for achieving good software engineering. The Software Engineering Observations highlight architectural and design issues that affect the construction of software systems, especially large-scale systems.17 Look-and-Feel ObservationsWe provide Look-and-Feel Observations to highlight graphical-user-interface conventions. These observations help developers design attractive, user-friendly graphical user interfaces that conform to industry norms.SummaryEach chapter ends with a summary that helps readers review and reinforce key concepts.Approximately 3,683 Index Entries (with approximately 4,490 Page References)We have included an extensive Index. This resource enables readers to search for any term or concept by keyword. The Index is especially useful to practicing programmers who use the book as a reference."Double Indexing" of All Visual Basic .NET Live-Code ExamplesVisual Basic .NET for Experienced Programmers has 192 Live-Code examples, which we have "double indexed." For every Visual Basic .NET source-code program in the book, we took the file name with the .vb extension, such as ShowColors.vb, and indexed it both alphabetically (in this case, under "S") and as a subindex item under "Examples." This makes it easier to find examples using particular features.Visual Basic .NET Multimedia Cyber Classroom, Second Edition and The Complete Visual Basic .NET Training Course, Second EditionWe have prepared an interactive, CD-ROM-based, software version of Visual Basic .NET How to Program, Second Edition, called the Visual Basic .NET Multimedia Cyber Classroom, Second Edition. This resource, ideal for corporate training and college courses, is loaded with interactive e-learning features. The Cyber Classroom is packaged with the Visual Basic .NET How to Program, Second Edition textbook at a discount in The Complete Visual Basic .NET Training Course, Second Edition. If you already have that book and would like to purchase the Visual Basic .NET Multimedia Cyber Classroom, Second Edition separately, please visit www.InformIT.com/cyberclassrooms. The ISBN number for the Visual Basic .NET Multimedia Cyber Classroom, Second Edition is 0-13-065193-1. Many Deitel Cyber Classrooms are available in CD-ROM and Web-based training formats.The CD-ROM provides an introduction in which the authors overview the Cyber Classroom's features. The textbook's 249 Live-Code example Visual Basic .NET programs truly "come alive" in the Cyber Classroom. If you are viewing a program and want to execute it, you simply click the lightning-bolt icon, and the program will run. You immediately will see-and hear, when working with audio-based multimedia programs-the program's output. Click the audio icon, and one of the authors will discuss the program and "walk you through" the code.The Cyber Classroom also provides navigational aids, including extensive hyperlinking. The Cyber Classroom is browser based, so it remembers sections that you have visited recently and allows you to move forward or backward among those sections. The thousands of index entries are hyperlinked to their text occurrences. Furthermore, when you key in a term using the "find" feature, the Cyber Classroom will locate occurrences of that term throughout the text. The Table of Contents entries are "hot," so clicking a chapter name takes you immediately to that chapter.Readers like the fact that solutions to approximately half the exercises in Visual Basic .NET How to Program, Second Edition are included with the Cyber Classroom. Studying and running these extra programs is a great way for readers to enhance their learning experience.Professionals and student users of our Cyber Classrooms tell us that they like the interactivity and that the Cyber Classroom is an effective reference due to its extensive hyperlinking and other navigational features. We received an e-mail from a reader who said he lives "in the boonies" and cannot attend a live course at a university, so the Cyber Classroom provided an ideal solution to his educational needs.Professors tell us that their students enjoy using the Cyber Classroom and spend more time on the courses and master more of the material than in textbook-only courses. For a complete list of the available and forthcoming Cyber Classrooms and Complete Training Courses, see the Deitel Series page at the beginning of this book, the product listing and ordering information at the end of this book or visit www.deitel.com, www.prenhall.com/deitel or www.InformIT.com/deitel.Deitel e-Learning Initiativese-Books and Support for Wireless DevicesWireless devices will play an enormous role in the future of the Internet. Given recent bandwidth enhancements and the emergence of 2.5 and 3G wireless technologies, it is projected that, within two years, more people will access the Internet through wireless devices than through desktop computers. Deitel Associates, Inc., is committed to wireless accessibility and has recently published Wireless Internet Mobile Business How to Program. To fulfill the needs of a wide range of customers, we are developing our content in traditional print formats and in new electronic formats, such as e-books, so that readers can access content virtually anytime, anywhere. Visit www.deitel.com for periodic updates on all Deitel technology initiatives.e-Matter Deitel Associates, Inc., is partnering with Prentice Hall's parent company, Pearson PLC, and its information technology Web site, InformIT.com, to launch the Deitel e-Matter series at www.InformIT.com/deitel in Fall 2002. The Deitel e-Matter series will provide professionals with an additional source of information on specific programming topics at modest prices. e-Matter consists of stand-alone sections taken from published texts, forthcoming texts or pieces written during the Deitel research-and-development process. Developing e-Matter based on pre-publication manuscripts allows us to offer significant amounts of the material well before our books are published.Course Management Systems: WebCT, Blackboard, CourseCompass, and Premium CourseCompassWe are working with Prentice Hall to integrate our How to Program Series courseware into four series of Course Management Systems-based products: WebCT, Blackboard, CourseCompass, and Premium CourseCompass. These enable instructors to create, manage and use sophisticated Web-based educational programs. Course Management Systems feature course customization (such as posting contact information, policies, syllabi, announcements, assignments, grades, performance evaluations and progress tracking), class and student management tools, a grade book, reporting tools, communication tools (such as chat rooms), a whiteboard, document sharing, bulletin boards and more. Instructors can use these products to communicate with their students, create online quizzes and exams from questions directly linked to the text and efficiently grade and track test results. For more information about these upcoming products, visit www.prenhall.com/cms. For demonstrations of WebCT, Blackboard and CourseCompass course materials, visit cms.prenhall.com/webct, cms.prenhall.com/blackboard and cms.prenhall.com/coursecompass, respectively.Deitel and InformIT NewslettersDeitel Column in the InformIT NewslettersDeitel Associates, Inc., contributes articles to the free InformIT weekly e-mail newsletter, subscribed to by more than 750,000 IT professionals worldwide. For registration information, visit www.InformIT.com and click the MyInformIT tab.Deitel Buzz Online NewsletterOur own free newsletter, the Deitel Buzz Online, includes commentary on industry trends and developments, links to articles and resources from our published books and upcoming publications, product-release schedules, challenges, anecdotes, and more. For registration information, visit www.deitel.com/newsletter/subscribe.html.The Deitel Developer SeriesDeitel Associates, Inc. is making a major commitment to .NET programming through our Deitel Developer Series. C# A Programmer's Introduction, C# for Experienced Programmers, Visual Basic .NET for Experienced Programmers and Visual C++ .NET for Experienced Programmers are the first .NET books in this new series. These will be followed by several advanced books, beginning with ASP .NET with Visual Basic .NET for Experienced Programmers and ASP .NET with C# for Experienced Programmers.The Deitel Developer Series is divided into three subseries. The A Technical Introduction subseries provides IT managers and developers with detailed overviews of emerging technologies. The A Programmer's Introduction subseries is designed to teach the fundamentals of new languages and software technologies to developers from the ground up. These books discuss programming fundamentals, followed by brief introductions to more sophisticated topics. Finally, the For Experienced Programmers subseries is designed for seasoned developers seeking to learn new programming languages and technologies without the encumbrance of introductory material. The books in this subseries move quickly to in-depth coverage of the intermediate features of the programming languages and software technologies being covered.ASP .NET with Visual Basic .NET for Experienced ProgrammersOur forthcoming publication ASP .NET with Visual Basic .NET for Experienced Programmers (available in 2003) is geared toward experienced .NET developers. This new book will cover enterprise...