As stated, web services are based on the exchange of messages using nonproprietary protocol messages. The messages themselves are not sufficient to define the web service platform. We actually need a list of standard components, including the following:
A language used to define the interfaces provided by a web service in a manner that is not dependent on the platform on which it is running or the programming language used to implement it
A common standard format to exchange messages between web service providers and web service consumers
A registry within which service definitions can be placed
The Web Service Description Language, also known as WSDL, (http://www.w3.org/TR/wsdl) is the de facto standard to provide a description of a web service contract exposed to clients. In particular, a WSDL document describes a web service in terms of the operations that it provides, and the data types that each operation requires as inputs and can return in the form of...