Unlike previous technologies for distributed computing (such as DCOM), web services make it unnecessary for both ends of the connection to be running the same operating system or to be programmed in the same language. For example, the server code might be written in VB.2005 on Windows 2000 while the client is a C++ program running on a Unix machine, or vice versa. In other words, while previous technologies required that the client and server be tightly coupled, web services permit them to be loosely coupled.
All that is necessary is that both server and client support the industry standard protocols HTTP, SOAP, and XML. HTTP is the protocol used by the Web. SOAP (Simple Object Access Protocol) is a lightweight, object-oriented protocol based on XML that, in turn, is a cross-platform standard for formatting and organizing information.