Introduction to ASP.NET
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This book in the Nutshell series covers the basics of the .NET development platform and new features in ASP.NET 1.1. The second edition includes bonus Visual Studio .NET add-in. This chapter is from the book,
ASP.NET in a Nutshell, by G. Andrew Duthie and Matthew MacDonald, O'Reilly Media, 2004, ISBN: 0596005202.
Introduction
ASP.NET is Microsoft’s latest technology for building web-based applications and services, a successor to Active Server Pages (ASP) that draws on the power of the .NET Framework development platform and the Visual Studio .NET developer toolset. To better understand ASP.NET, it is important to understand some key concepts of the .NET development platform. It is also helpful to grasp object-oriented development (OOD), which is at the very heart of the .NET Framework that provides the foundation for ASP.NET development. In this chapter, we’ll review these concepts, look at what’s new in ASP.NET (versus classic ASP), review new features in ASP.NET 1.1, and discuss choosing a language to suit your needs.
.NET Platform Fundamentals
At the core of Microsoft’s .NET platform initiative is a new set of technologies known collectively as the .NET Framework, which we’ll refer to commonly as the Framework. The Framework provides a platform for simplified rapid development of both web-based and Windows-based applications. The Framework has two primary components, the Common Language Runtime (CLR) and the Framework Class Library (FCL).
As with many new technologies, there are a host of new terms and acronyms to understand, so we’ll introduce and explain the most important ones in the Framework over the next several sections.
The Common Language Runtime (CLR) The CLR is the execution environment for code written for the .NET Framework. The CLR manages the execution of .NET code, including memory allocation and garbage collection (which helps avoid memory leaks), security (including applying differing trust levels to code from different sources), thread management, enforcing type-safety, and many other tasks.
The CLR works with every language available for the .NET Framework, so there is no need to have a separate runtime for each language. Code developed in a .NET language is compiled by the individual language compiler (such as the Visual Basic .NET compiler) into an intermediate format called (appropriately enough) Intermediate Language (IL). At runtime, this IL code generated by the compiler is just-in-time (JIT) compiled by the CLR into native code for the processor type the CLR is running on. This compilation provides the flexibility of being able to develop with multiple languages and target multiple processor types while still retaining the performance of native code at execution time.
While there is some up-front cost on first execution to the JIT compilation model, the Framework also offers the ability to pregenerate native code at install time through a utility called NGen.exe. This utility eliminates the startup cost of JIT compiling the code, at the expense of some of the optimizations that are available with JIT compiling.
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