Building Web Services with Visual Studio .NET
In a real world scenario, applications have to get information from other programs for various purposes. These programs may be located on the local system, on an Intranet or on the Internet.
Java introduced Remote Method Invocation (RMI) and CORBA for achieving these types of tasks. With RMI, developers can call methods in a remote system. With the help of CORBA, developers can call methods running in a totally different operating system across networks. The main difficulty involved with these technologies is that developers have to write lot of source code for invoking the required methods. Moreover, there is no visual environment available for coding RMI and CORBA. These difficulties were completely eliminated with the introduction of Web Services in .NET Framework.
The main concept behind Web Services is that other applications can consume and invoke them. They can call methods and functions from any system over the Web through HTTP. They combine the power of COM and DCOM and generate SOAP by default. SOAP stands for Simple Object Access Protocol and it is used by the .NET Framework to call the appropriate Web Service via eXtensible Markup Language (XML). The end result of a .NET Web Service by default will be XML; however, you can build a GUI application to handle the services. It can be either a Windows Application (WinForm) or a Web Application (ASP.NET)
The main point to note is that Web Services don't have user-interfaces (GUI controls)—the invoking application will have the required visual interfaces. You don't have to learn anything about SOAP and XML to create Web Services. Instead, the .NET Framework handles the entire work for you. Moreover, Microsoft's flagship product, Visual Studio .NET further simplifies the development of Web Services. In this article, you will learn how to create and consume Web Services with Visual Studio .NET. In order to work out the steps outlined in this article, you should install Visual Studio .NET under Windows 2000 Professional, Windows XP Professional, or Windows 2003 Server. The steps given below may slightly differ if you use standard editions of Visual Basic .NET and Visual C# .NET.