Overview

Great services are not canceled by one act or by one single error.

Benjamin Disraeli

Web services would be much easier to come to grips with if not for the ambiguous, misleading, and misused name. "Services," in computer circles, means many things to many people. It is used, quite appropriately, to refer to any external entity that does work on your behalf, so to speak. So people are used to such terms as "print services," "directory services," "file services," and "security services," to name a few. It has got to the point where in the context of enterprise networking there is an overall connotation that services are provided by "middleware" la J2EE, IBM's WebSphere Application Server, BEA WebLogic, IBM MQSeries, and Microsoft BizTalk Server. The problem is that Web services per se are not "middleware."

Web services are, indeed, services, and they are delivered across the Web. But they are meant to deliver high-level services even modular applications. Start off by thinking of Web services in terms of:

• Credit-card authorization

• International currency-rate converter

• Stock-quote provider

• Package delivery-status locator

• Shipping-rate calculator

• Local weather update

• Local traffic update

• Personalized horoscope

• User authentication for example, with two-factor authentication

Figure 8.1 illustrates the concept of Web services in the context of an e-commerce transaction, in which the e-commerce application calls up various Web services to perform specific, specialized functions. Figure 8.2 emphasizes this theme of Web services providing specific functions by showing just some of the ways that a portal, in this case Lycos's...