BPEL - Asynchronous Interactions

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The Client BPEL Process sends a request to the Service BPEL Process (d1 in the figure given below), and waits until the service replies (d2 in the figure given below).

For example, a user requests a subscription to an online application form for admission to a college and the request cannot be confirmed unless it is accepted at the admission office.

Asynchronous Interactions

  • The Client BPEL Process needs an invoke activity to send the request and a receive activity to receive the reply.

  • The Service BPEL Process needs a receive activity to accept the incoming request and an invoke activity to return either the requested information or a fault.

    Note − The difference between responding from a synchronous and asynchronous BPEL process is that the synchronous service uses a reply activity to respond to the client and an asynchronous service uses an invoke activity.

  • As with all partner activities, the Web Services Description Language (WSDL) file defines the interaction. The WSDL file is as shown below.

WSDL File

<wsdl:portType name = "BPELProcess">
   <wsdl:operation name = "process">
      <wsdl:input message = "client:BPELProcessRequestMessage"/>
   </wsdl:operation>
</wsdl:portType>

<wsdl:portType name = "BPELProcessCallback">
   <wsdl:operation name = "processResponse">
      <wsdl:input message = "client:BPELProcessResponseMessage"/>
   </wsdl:operation>
</wsdl:portType>
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