What are Web Services?
The W3C defines Web services as follows: “A Web service is a software system identified by a URL, whose public interfaces and bindings are described using XML. Its definition can be discovered by other software systems. These systems may then interact with the Web service in a manner prescribed by its definition, using XML based messages conveyed by Internet protocols” (W3C, 2006).
At a conceptual level, Web services consist of a service provider, a service requestor, and a service registry, as shown in Figure 1. The service requestors and providers communicate with each other by exchanging messages using open standards and protocols. Another important feature is that the requestors and providers form loosely coupled systems, meaning that the development of each of the systems is done in a truly distributed manner. They are developed, implemented, and maintained independent of each other.