Each Web service in a process, represented by receive, reply, and invoke activities, must have a service interface. The interface describes the operations provided by the service.
You can choose to add a callback interface, which allows the service provider to invoke operations on the service consumer. For example, in a service interface, the process sends an order and the partner replies with an order ID. In a callback interface, the partner can send an order shipment notice.
When you add a callback interface, Process Developer generates a standard BPEL partner link type for that participant and stores it in a WSDL. This makes the participant relationship clear for future users of the WSDL and allows new processes that use the service interface to automatically see the callback interface.
The details for creating a callback interface are the same as creating a service interface. See:
Creating a New Process Service Consumer Interface
Creating a New Partner Service Interface
Process Developer adds the BPEL-required details, namely partner link type definitions, to a new WSDL. It adds definitions that need to be seen by clients of the process in a file named [process].public.wsdl. It places definitions that are private to the process (that is, partner link types for partner services) in a file named [process].public.wsdl.
The Callback participant displays as a child participant in the Participants view.
Creating New Activities from the Participants View