As with a synchronous transaction, when the BPEL process service component is on the service side of an asynchronous transaction, it 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 this and responding from a synchronous BPEL process: a synchronous BPEL process uses a reply activity to respond to the client and an asynchronous service uses an invoke activity.

For more information about asynchronous interactions, see Invoking an Asynchronous Web Service from a BPEL Process.