Chapter III introduced standards for Web service specification, such as WSDL and SOAP. With the use of such standards, Web service designers can model the functionality of a service in terms of inputs and outputs, thus allowing the consumers of the service to understand what to expect (and what not to expect) from the service, before actually using it. As we have said already, a Web service offers some well defined functionality to its consumers, which, however, due to the very essence of the Web service, has a rather focused and narrow scope. The reason is that, in general, we aim to develop Web services that are as much useful as possible for a wide range of consumers. Thus, the Web service becomes a reusable building.block for something more complex such as a business service. It is unlikely that a business level service can be provided by a single Web service. Instead, a complex business service has to be layered on top of several Web services that coordinate.with each other to deliver the business service. The capability for coordination however, is not unique to Web services. Business resources (people, activities, equipment, etc.) must be coordinated to deliver processes (Dayal, Hsu, & Ladin, 2001). Business processes themselves must be coordinated within a single company or even across several companies, in order to deliver higher level business results such as the fulfillment of a supply chain.