WSDL Document Structure

WSDL — the Web Services Description Language — is yet another language that was built by using XML. It is used to define a Web service. Like a SOAP message, a WSDL document is divided into four parts:

1. Definition of ports: We don’t really like the use of the word port here, but we’re stuck with it. A port is a connection point. The WSDL port defines a Web service, the operations that can be requested, and the messages that can be used. In other words, the WSDL description defines what you can do and how you do it after you connect to the port. Another way of describing it is that it is an XML definition of a program function.

1. Definition of messages: Here you see the definitions of the data items for each of the operations that are defined under the specification of the port. These definitions act as templates for the requesting program to make requests and for it to understand the responses it receives. In reality, these definitions are what a programmer thinks of as function calls. And as you may expect, they relate to a name space.

1. Definition of types: This defines the data types that are used by the Web service. These relate to a name space as well.

1. Definition of binding: This is technical stuff for the programs involved. It defines exactly how the two programs can connect to each other.