Class libraries in .NET

The .NET Framework provides a large and very rich library of classes to be used and extended by application developers. Reuse and extension of these classes will allow developers to be more productive and to develop more robust and feature-rich applications in a shorter time frame because the class library provides many features that previously had to be built from scratch.

To make a .NET class library easier to work with and understand, it is divided into namespaces. At the highest level of the class-library is the System namespace, which act as the root namespace contains all the base data type classes used by application developers to build frameworks and applications.

The .NET framework class libraries are available to all .NET languages like the .NET class library are common to all languages of .NET it means the way one access files in C# will be exactly the same in VB.NET and in fact all other languages of .NET.

The .NET Framework class library contain classes that allow developing the following type of applications:

• Console applications

• Window applications

• Windows services

• ASP .NET Web applications

• Web services

• Windows communication foundation applications

• Windows presentation foundation applications

• Window workflow foundation applications

The library’s classes are organized using a hierarchy of namespace. For example, all the classes of performing I/O operations are located in the System.IO namespaces, and classes that manipulate regular expressions are located in the System.Text.RegularExpressions namespace.

The services and corresponding namespaces offered by these class libraries include the following:-

• System Types (System): Includes definitions for most simple data types, conversion functions between types, some mathematical functions, arrays and ways to handle exceptions.

• Input/Output (System.IO): Includes classes to read and write to data streams and to files on drives.

• Configuration (System.Configuration): Includes classes to establish configuration settings and to handle errors using the settings.

• Networking (System.Net): Includes classes to work with networking protocols such as IP and sockets.

• Data Access (System.Data): Includes classes to interact with external data, typically a database. This namespace includes most of ADO.NET, which is used by the ASP.NET data controls.

• Reflection (System.Reflection): Includes classes that allow a program to look at itself to identify its own characteristics, such as specialty data types and the organization of the code.

• Globalization (System.Globalization): Includes classes that hold culture-specific settings such as the syntax of dates and currency.

• Data Structure (System.Collections): Includes classes to organize and maintain sets of data within .NET including lists, dictionaries, and hash tables.

• Web Application Model (System.Web): Includes classes that provide a programming model for productive web pages.

• Painting and Drawing (System.Drwaing): Includes classes that can interface with the graphical interface. This namespace includes many classes for specific types of renderings, including pen, brush, and imaging.

• Security (System.Security): Includes the classes to implement the foundation of security, particularly the system of permissions.

• Tracing and Diagnostics (System.Diagnostics): Includes classes to analyze problems, including the dissection of system processes, performance counters, and event logs.

• Window (client) application model (System.Windows.Forms): Includes classes that allow the implementation of the windows user interface.