Web Services are designed to allow applications of all kinds to communicate despite their many differences in design and runtime environments. Web Services have an added feature in that larger Web Services can be built from smaller ones. If one Web Service returns tomorrow's weather given a ZIP Code and another Web Service returns fashion tips based on the weather, a third Web Service could then call the other two and provide fashion tips when given a ZIP Code. It could also provide value by searching for the best prices for its fashion recommendations—perhaps by invoking another Web Service. Each of these Web Services might invoke code running on a mainframe, a Unix machine, or a Windows machine. It really doesn't matter what the runtime environment is as long as each Web Service knows how to communicate using XML dialects.

NOTE

Although the idea behind Web Services is not a complex concept, in practice, it could revolutionize how computer applications are built for the foreseeable future. The ease with which applications from different departments, companies, and countries can invoke each others' services will have an enormous affect on how various groups of technologists collaborate on software development. The possibilities of creating new applications from existing building blocks that are available from all over the world are limitless.

What Are Web Services Used For?