A Web Services Primer

Looking back over the last six years, it is hard to imagine networked computing without the Web. The reason why the Web succeeded where earlier hypertext schemes failed can be traced to a couple of basic factors: simplicity and ubiquity. From a service provider’s (e.g. an e-shop) point of view, if they can set up a web site they can join the global community. From a client’s point of view, if you can type, you can access services. From a service API point of view, the majority of the web’s work is done by 3 methods (GET, POST, and PUT) and a simple markup language. The web services movement is about the fact that the advantages of the Web as a platform apply not only to information but to services.

By “services”, I don’t mean monolithic coarse-grained services like Amazon.com, but, rather, component services that others might use to build bigger services. Microsoft’s Passport, for instance, offers an authentication function exported on the Web. So hypothetically, an electronic newspaper like the Washington Post can avoid creating its own user authentication service, delegating it to Passport.

Oracle’s dynamic services whitepaper provides other examples of component services that are reusable building blocks: currency conversion, language translation, shipping, and claims processing, A more formal definition of a web service may be borrowed from IBM’s tutorial on the topic.

Web services are a new breed of Web application. They are self-contained, self-describing, modular applications that can be published, located, and invoked across the Web. Web services perform functions, which can be anything from simple requests to complicated business processes…Once a Web service is deployed, other applications (and other Web services) can discover and invoke the deployed service.

Continue to read article on XML.com