Where is WSDL?

The only way that applications like InfoPath can access a specific SOAP endpoint is to know both the target URL value and the expected message format. Neither SOAP nor XML can fully describe this type of information. It’s the job of WSDL to provide the SOAP service description using an XML schema to describe the expected message format and the service invocation requirements. WSDL defines Web Services as a series of network endpoints or virtual ports. The combination of these endpoints and an XML-based message description enables interface reusability. A WSDL document defines a series of XML elements that describe the Web Service interface. Table 4.1 shows the main WSDL document elements and their use.

Table 4.1. WSDL Document Definition Elements

Name	Description
Type	A container for type definitions using an agreed-upon type system
Message	An abstract definition of the data being communicated
Operation	A description of the actions supported by the service
Port Types	The abstract set of operations supported by the services
Port Type	A set of operations supported by one or more endpoints
Bindings	The protocol and data format required for a particular port type
Port	The definition of a single endpoint defined as a combination of bindings and network addresses
Service	A collection of related endpoints