A transaction management engine, such as a business process management (BPM) engine, can allow an application to define transaction demarcations in order to ensure that portions of a workflow are processed atomically. In one such system, a JMS message is queued to the workflow as part of an existing transaction. If that transaction commits, the queued JMS message ensures that the workflow will be invoked in a new transaction that allows the workflow to perform the next unit of work in the newly initiated transaction. When the unit of work is completed, the workflow queues another JMS message. If this transaction commits, the transaction ensures the unit of work has executed in a transaction. When the workflow is invoked again due to the second JMS message, the workflow can continue its operation in a different transaction.