1.1 The .NET Framework
The .NET Framework sits on top of the operating system, which can be any flavor of Windows, and consists of a number of components. Currently, the .NET Framework consists of:
Figure 1-1 breaks down the .NET Framework into its architectural components.
The Common Language Runtime (CLR) executes your program on your web server. The CLR activates objects, performs security checks on them, lays them out in memory, executes them, and handles garbage collection.
In Figure 1-1, the layer on top of the CLR is a set of framework base classes, followed by an additional layer of data and XML classes, plus another layer of classes intended for web services and Web Forms, and Windows forms. Collectively, these classes are known as the Framework Class Library (FCL). With more than 5,000 classes, the FCL facilitates rapid development of ASP.NET applications. This same class library is used for desktop applications as well.
Microsoft .NET supports a Common Language Specification (CLS) that allows you to choose the syntax with which you are most comfortable. You can write classes in C# and derive from them in VB.NET. You can throw an exception in VB.NET and catch it in a C# class. Suddenly the choice of language is a personal preference rather than a limiting factor in your application's development.
The set of framework base classes supports rudimentary input and output, string manipulation, security management, network communication, thread management, text manipulation, reflection, and collections functionality, and so on.
Above the base class level are classes that support data management and XML manipulation. The data classes support persistent management of data that is maintained on backend databases. These classes include the Structured Query Language (SQL) classes to let you manipulate persistent data stores through a standard SQL interface. Additionally, a set of classes called ADO.NET allows you to manipulate persistent data. There are classes optimized for the Microsoft SQL Server relational database, and there are generic classes for interacting with OLE DB compliant databases. The .NET Framework also supports a number of classes to let you manipulate XML data and perform XML searching and translations. Chapters Chapter 8 through Chapter 13 discuss the data-handling aspects of the .NET Framework.