Codenotes for .Net

Chapter 1 An introduction to the .net framework What is .NET? .NET is Microsoft's new strategy for the development and deployment of software. Depending on your interests and development background, you may already have a number of preconceived notions regarding .NET. As we will see throughout this CodeNote: -.NET fundamentally changes the way applications execute under the Windows Operating System. -With .NET Microsoft is, in effect, abandoning its traditional stance, one which favors compiled components, and is embracing interpreted technology (similar, in many ways, to the Java paradigm). -.NET brings about significant changes to both C++ and Visual Basic, and introduces a new language called C# (pronounced "C sharp"). .NET is built from the ground up with the Internet in mind, embracing open Internet standards such as XML and HTTP. XML is also used throughout the framework as both a messaging instrument and for configuration files. These are all noteworthy features of .NET, or more accurately the .NET Framework, which consists of the platform and tools needed to develop and deploy .NET applications. The .NET Framework can be distilled into the following three entities: 1. The Common Language Runtime (CLR), which is the execution environment for all programs in the .NET Framework. The CLR is similar to a Java Virtual Machine (VM) in that it interprets byte code and executes it on the fly, while simultaneously providing services such as garbage collection and exception handling. Unlike a Java VM, which is limited to the Java language, the CLR is accessible from any compiler that produces Microsoft Intermediate Language (IL) code, which is similar to Java byte code. Code that executes inside the CLR is referred to as managed code. Code that executes outside its boundaries is called unmanaged code. 2. The Runtime classes, which provide hundreds of prewritten services that clients can use. The Runtime classes are the building blocks for .NET applications. Many technologies you may have used in the past (ADO, for example) are now accessed through these Runtime classes, as are basic operations such as I/O. Traditionally, every language had its own unique supporting libraries, accessible only from that particular language. String manipulation, for example, was afforded to VB programmers via the Visual Basic runtime, whereas C++ programmers depended on libraries such as STL for similar functionality. The .NET Runtime classes remove this limitation by uniformly offering services to any compiler that targets the CLR. Those familiar with Java will find the Runtime classes analogous to the Java Class Libraries. 3. Visual Studio.NET (VS.NET), which is Microsoft's newest version of Visual Studio. VS.NET includes VB.NET, "managed" C++, and C#, all of which translate source code into IL code. VB.NET and VC.NET are the new versions of Visual Basic and Visual C++, respectively. C# is a new Microsoft language that at first glance appears to be a hybrid of C++ and Java. .NET development does not have to be limited to these languages, however. Any component or program produced by an IL-aware compiler can run within the .NET Framework. (As of this writing, other companies have announced IL compilers for Perl, Python, and COBOL.) VS.NET also comes with a fully Integrated Development Environment (IDE), which we will examine in Chapter 7. Note the VS.NET IDE now houses the development environments for both Visual C++ and Visual Basic. Outline of the Book In this chapter we will examine the three fundamentals of the .NET Framework previously listed. Chapter 2 provides brief installation instructions. Because .NET was still in beta release at the time of writing, these instructions may be out of date. Readers are encouraged to consult the online instructions at aNET0Brill, Gregory is the author of 'Codenotes for .Net', published 2002 under ISBN 9780812991895 and ISBN 0812991893.