Understanding WSDL

This is an attempt to explain WSDL in the simplest manner

About WSDL

• WSDL stands for Web Service Definition Language.
• It is a contract to the web service that is expressed in XML. To understand better this can be compared to an Interface in Java or a Package in Oracle which acts as a contract between the client and the system.

Structure of WSDL (parallels are drawn to Java wherever possible)

1. What are the capabilities of the Service? 
• What are the operations(methods) provided by the Service and what are the messages(parameters) that each operation requires?
• The messages can be input(parameters), output(return value) or faults(exception)
2. How can the Service be accessed?
• What is the protocol(SOAP) and what is the encoding(document)?
3. Where can the Service be accessed?
• What is the endpoint(address) of the Service?

 Illustration of the WSDL Structure
The CreditService web service developed earlier is used to illustrate