When the BPEL process service component is on the client side of an asynchronous transaction with a timeout, it needs an invoke activity to send the request and a pick activity with two branches: an onMessage branch and an onAlarm branch. If the reply comes after the time limit has expired, the message goes to the dead letter queue. As with all partner activities, the WSDL file defines the interaction.

For more information about asynchronous interactions with a timeout, see Selecting Between Continuing or Waiting on a Process with a Pick Activity.