In addition to setting the WS-AT participation property, if a client calls a web service that is a BPEL process, for that web service to be enlisted in the caller's transaction, the callee BPEL process must have the transaction property set in its composite.xml file.

<property name="bpel.config.transaction">required</property>

This setting ensures that, if an error occurs (such as a database adapter invocation failing due to an integrity constraint violation), a transaction rollback is successfully completed.

For more information about setting the transaction property, see How to Add a BPEL Process Service Component, How to Define Deployment Descriptor Properties in the Property Inspector, and Transaction Semantics.