Figure 1.1 shows an overview of the .NET platform.
The central component of the .NET platform is the .NET Framework. This consists of a runtime environment called the common language runtime and a set of supporting libraries. The runtime environment controls the installation, loading, and execution of .NET applications. The libraries provide code for common programming tasks, thus increasing developer productivity. The libraries also provide a layer over many OS APIs, providing an isolation from OS dependencies.
Most enterprise applications and Web services require back-end servers to perform operations such as storing data, exchanging messages via e-mail, and so on. Microsoft's family of .NET servers such as SQL Server, Exchange Server, and so on, can be used to obtain such functionality. The family also includes some special servers that provide a higher level of integration and aggregation of Web services. BizTalk Server and Commerce Server, application frameworks for e-commerce, fall under this category.
The .NET platform also includes a set of developer tools such as Visual Studio .NET and programming languages such Visual Basic .NET and C# (pronounced C sharp).
In developing applications, developers can also take advantage of the foundation services offered by Microsoft or other software vendors. We take a look at a few important foundation services in a later section of this chapter.
Finally, the Windows operating system is at the base of the .NET platform. Operating systems such as Windows NT, Windows 2000, and Windows XP do not come preinstalled with the .NET Framework. However, one can install the framework separately by downloading it from Microsoft's Web site. Windows .NET and the newer releases of the Windows operating system are expected to ship with elements of the .NET vision.