Applied XML Programming for Microsoft .NET.pdf - Csbdu.in

Figure 13-2: The ASP.NET architecture to process page and Web service requests.The connection between the IIS process (the executable named inetinfo.exe) and theHTTP pipeline (the worker executable named aspnet_wp.exe) is established through anamed pipe—that is, a Win32 mechanism for transferring data over a network. As you'dexpect, a named pipe works just like a pipe: you enter data in one end, and the samedata comes out at the other end. Pipes can be established both locally to connectprocesses and between remote machines.After the ASP.NET worker process receives a request, it routes that request throughthe .NET Framework HTTP pipeline. The entry point of the pipeline is the HttpRuntimeclass. This class is responsible for packaging the HTTP context for the request, whichis nothing more than familiar Active Server Pages (ASP) objects such as Request,Response, Server, and the like. These objects are packed into an instance of theHttpContext class, and then a .NET Framework application is started.The WebService ClassIn the .NET Framework, a Web service is an ordinary class with public and protectedmethods. The Web service class is normally placed in a source file that is saved with an.asmx extension. Web service files must contain the @ WebService directive thatinforms the ASP.NET run time about the nature of the file, the language in usethroughout, and the main class that implements the service, as shown here:The Language attribute can be set to C#, VB, or JS. The main class must match thename declared in the Class attribute and must be public, as shown here:457