Asynchronous Interactions with a Timeout

The Client BPEL Process sends a request to the Service BPEL Process (d1 in the below figure), and waits until the service replies or until a certain time limit is reached, whichever comes first. (d2 in the below figure).

For example, a user requests a subscription to an online application form for admission to a college and the request is cancelled if the user does not receive a confirmation reply within a specified amount of time.

The Client BPEL Process 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.

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.

As with all partner activities, the Web Services Description Language (WSDL) file defines the interaction.