WSDL is an XML based language that is used for describing web services as a set of endpoints that operate on messages that contain either document-oriented or procedure-oriented information. The operations and messages are described abstractly and then bound to a concrete network protocol and a message format to define an endpoint. Related concrete endpoints are combined into abstract endpoints or services. WSDL is extensible, enabling the description of endpoints and their messages, regardless of the message formats or network protocols used to communicate.

Your development environment is designed to analyze the description of a web service to identify the following:

• Data object types: the entities contained in a web service and the data fields definitions
• Operations: the operations that describe what a web service does

The following example illustrates the structure of a WSDL file:

<definitions>
<types>
   <definition of types>
</types>
<message>
   <definition of a message>
</message>
<portType>
   <definition of a port>
</portType>
<binding>
   <definition of a binding>
</binding>
</definitions>

The following elements are used in the basic structure of a WSDL file:

• Types: These are the data types that the web service uses.
• Message: This includes the data elements of an operation. It is comparable to the parameters of a function call.
• Port type: This includes the operations and their parameters that the web service provides. It is comparable to a function library.
• Binding: This defines the message format and protocol details for each port.