Understanding WSDL

Why WSDL...

• When we create a service, we typically do it because we want other people to use it or reuse it.

• In order for them to do that, they need to know ,
• what information to send to the service,
• what information the service is going to send back,
• and where to find the service in the first place.

• As communications protocols and message formats are standardized in the web community, it becomes increasingly possible and important to be able to describe the communications in some structured way.

• WSDL addresses this need by defining an XML grammar for describing network services as collections of communication endpoints capable of exchanging messages.

Specifically WSDL is..

• is an XML document
• used to describe Web services
• specifies the location of the service
• specifies  the operations (or methods) the service exposes

The WSDL Document Structure..

Abstract Part : Describes

• the messages it sends and receives
• the operation associates a message exchange pattern with one or more messages

• Types– a container for data type definitions using some type system (such as XSD).
• Message– an abstract, typed definition of the data being communicated.
• Operation– an abstract description of an action supported by the service.
• Port Type–an abstract set of operations supported by one or more endpoints.

Concrete part : specifies

• transport and wire format details for one or more interfaces
• a port (an endpoint) associates a network address with a  binding
• a service which groups together endpoints that implement a common interface

• Binding– a concrete protocol and data format specification for a particular port type.
• Port– a single endpoint defined as a combination of a binding and a network address.
• Service– a collection of related endpoints