The .NET Framework Software Development Kit (SDK) and Visual Studio .NET represent the two halves of the .NET Framework. The SDK includes the Common Language Runtime (CLR) which executes the code on your system and comes with an extensive set of classes and interfaces. It also includes compilers for Visual Basic .NET, C++ .NET and the newest language, C#. In addition, support for J#, Microsoft’s latest entry into the Java world and a replacement for the litigiously and technically challenged J++ is due out soon. Architecturally all of this represents a completely different technology model for Microsoft.

One of the features of the new framework is that all supported languages are compiled into a common Intermediate Language (IL). It sits on your system as IL until runtime when the CLR compiles the parts of your IL code that it needs into machine code and arranges it all into assemblies. Assemblies are managed collections of server components like dlls and executables. The assemblies also include metadata that a CLR needs to execute the code such as information about classes, interfaces, method names and return values, parameter values, and version information. ASP .NET’s use of assemblies and caching makes it a viable platform for even the largest enterprise web applications. In application development, assemblies and the metadata will simplify application distribution. The metadata provides the CLR information to help the CLR successfully run the application. This should reduce the incidence of developers and support staff spending days poking around registries and tinkering with values. The CLR provides your application with services, abstracting server resources from the developer. The new services promise to really improve the portability and distribution of .NET applications. A lot of people think this makes the CLR sounds an awful lot like a Java Virtual Machine (JVM).