The Web Services Namespaces

Web services are supported by several namespaces in the .NET Framework, as listed in the following table.

Namespace	Description
System::Web::Services	Contains classes used to build and use Web services
System::Web::Services::Configuration	Contains classes that configure how Web services run
System::Web::Services::Description	Contains classes that let you describe Web services using WSDL
System::Web::Services::Discovery	Contains classes that let client code locate Web services elsewhere on the Web
System::Web::Services::Protocols	Contains classes that define the protocols used to transmit data in Web services

The System::Web::Services namespace contains the classes that you use to create and use Web services. It isn’t a large namespace, and the three main classes are listed in the following table.

Class	Description
WebMethodAttribute	An attribute that marks a method as callable from remote Web clients
WebService	An optional base class used to build Web services
WebServiceAttribute	An attribute used to add additional information to a class that implements a Web service

Web services will often derive from WebService, but doing so is necessary only if you want access to the common Microsoft ASP.NET objects, as listed in the following table.

Property	Description
Application	Gets the application state object, which is common to all sessions
Context	Gets the ASP.NET HttpContext object for the current HTTP request
Server	Returns an HttpServerUtility object that provides utility methods for working with the Web server
Session	Gets the HttpSessionState object for the current request
User	Returns an ASP.NET User object, which represents the current user and can be used for authentication purposes

If you don’t need access to these properties, you don’t need to derive a class from WebService.