Partner Link Types and Roles

The type determines the relationship between a process and its partners by defining the roles played by each service in a conversation. The relationship is further determined by specifying the port type provided by each service to receive messages. Each role specifies one port type in the WSDL file.

Roles determine the conversational aspect of this process or its partner. You use a single role for a synchronous operation as the results are returned using the same operation. You use two roles in an asynchronous operation as the partner role switches during a callback.

It is easy to confuse partner links and partner link types, however:

• Partner link types and roles are special WSDL extensions defined by the BPEL specification. As such, they are defined in WSDL files, not in the process BPEL file.

• Partner Link is a BPEL 2.0 element. It is defined in the process BPEL file.

Partner link types are prerequisites to the Partner Link element definition. A Partner Link element can only be defined by referring to a particular partner link type and role which, as mentioned, must be defined in a WSDL file.