The business process execution language (BPEL) is the de-facto standard for modelling business processes using the web-service stack. In order to enable transaction processing in typically long running business processes, BPEL uses a transaction model based on compensation. This transaction model can be described using WS Business Activity.

This diploma thesis describes how transactions in BPEL processes can be extracted from a BPEL engine and can be coordinated externally using an external coordinator based on WS-Coordination and WS-Business Activity. Therefore it is shown how WS-Business Activity is not enough to describe the relations between BPEL scopes that represent the transaction relevant elements inside BPEL. Additionally the mapping from BPEL scope hierarchies to WS-Coordination hierarchies is shown.

A prototype, based on the open source ActiveBPEL engine has been built and is described in detail.