CSCI 3327 Visual Basic Chapter 1: Introduction to Visual Basic

1. CSCI 3327 Visual Basic Chapter 1: Introduction to Visual Basic UTPA – Fall 2011

2. Demo

3. Objectives • In this chapter, you will • Recall basic components in a computer system • Learn the evolution of programming language • Learn the history of Visual Basic • Find the differences between structural programing and object-oriented programing • Become aware of the .NET Framework for Visual Basic

4. CSCI 1380: Elements of a Computer System • Hardware • CPU • Main memory • Secondary storage • Input / Output devices • Software • System programs • Application programs (e.g. Visual Basic)

5. Programming Languages • Machine language • Assembly language • High-level language

6. History of Visual Basic • BASIC (Beginner's All-purpose Symbolic Instruction Code) • 1960, Profs Kemeny and Kurtz • 1970s, Bill Gates implemented BASIC on several early PCs • Late 1980s ~ early 1990s, Microsoft developed Microsoft Windows graphical user interface (GUI) • Basic  Visual Basic • Visual Basic is created in Integrated Development Environment (IDE)

7. Milestones • Structured Programming  Disciplined approach to creating clear, correct and easy to modify programs. Pascal 1971 • Procedural Programming • Object Technology  Packaging Scheme for creating meaningful software units

8. Object Technology • We humans are very good in recognizing and working with objects, such as a pen, a dog, or a human being. • We learned to categorize them in such a way that make sense to us. We may categorize them as animate object, inanimate objects, pets, friends, etc.

9. Object Technology (cont'd) • We some times classify objects based on their attributes, for example, green apples or red apples, fat or slim people, etc. • If you think about it each object has many attributes. If I ask you list the attributes of an orange, you probably could list many things such as color, shape, weight, smell, etc.

10. Object Technology (cont'd) • In addition to attributes, all objects exhibit behaviors. • A dog eats, barks, wags its tail, plays, and begs. A dog exhibits many more other behaviors than this short list. • Another thing we need to remember about objects is that objects interact between each other.

11. Object Technology in Visual Basic • Visual Basic • Object-oriented • E.g. forms, labels, buttons, radios, checkboxes, etc. • Properties of objects • E.g. background color of forms • Event-driven • Behaviors  events of objects • E.g. clicks

12. XML (eXtensible Markup Language) • HTML has fixed tags which is a limitation • XML is definable • Separation of data from description of data (data independence) • XML can be used by any software or language

13. ARTICLE.XML file • <?xml version = "1.0"?> • <!-- Article structured with XML --> • <article> • <title>Simple XML</title> • <date>December 6, 2001</date> • <author> • <firstName>John</firstName> • <lastName>Doe</lastName> • </author> • <summary>XML is pretty easy.</summary> • <content>In this chapter, we present a wide variety of examples that use XML. • </content> • </article>

14. What is .NET? • .NET is an Internet and Web based infrastructure • .NET delivers software as Web Services– XML based. • .NET will run in any browser on any platform • .NET framework is the infrastructure for the new Microsoft .NET Platform.

15. What are Web Services? • Applications that run on a web server and communicate with other applications • The basic platform of Web services is XML + HTTP

16. What is .NET built on? • Windows Servers: • SQL • Application Center • Commerce Server • Mobile Information Server • Exchange Server • BizTalk Server • Internet Security • Host Integration

17. .NET Framework • A software platform • Language-neutral • Designed for cross-language compatibility • Applications written in VB may reference a DLL file written in any other language • 2 components: • Common Language Runtime (CLR) • Class Libraries

18. Common Language Runtime • Execution Engine of .NET • Manages the execution of programs and provides core services: • Code compilation • Memory allocation • Thread management • Garbage collection

19. Common Language Runtime (cont'd) • Output of .Net compilation contains a special type of code called Microsoft Intermediate Language (MSIL); it is not executable • MSIL is independent of any specific CPU. • CLR translates MSIL to executable code when the program is executed • Executable code is produced using JIT (just-in-time) compiler. The native code produced by JIT is specific for the CPU.

20. Class Libraries • Designed to integrate with the common language runtime • This library gives the program access to runtime environment • The class library consists of lots of prewritten code that all the applications created in VB .NET and Visual Studio .NET will use • The code in Visual Basic for all the elements like forms, and controls actually comes from the class library

21. Reasons Why Developers Build Applications Using the .NET Framework • Improved Reliability • Increased Performance • Developer Productivity • Powerful Security • Integration with Existing Systems • Ease of Deployment • Mobility Support • XML Service Support • Support for over 20 Programming Languages • Flexible Data Access

22. Visual Basic (VB) • Forms designer • In-place menu editor • Automatic control anchoring and docking • Integrated Development Environment (IDE) • Create Web applications using the shared Web forms designer • Full object-oriented constructs - inheritance, encapsulation, and polymorphism

23. Concepts of Object-Oriented Programming • Objects • Classes • Data Abstraction and Encapsulation • Inheritance • Polymorphism

24. VB Object-Oriented Approach • Emphasis on data rather than procedure • Programs are divided into Objects • Data is hidden and cannot be accessed by external functions • Objects can communicate with each other through functions • E.g. click event of a button • New data and functions can be easily added whenever necessary • Follows bottom-up approach