A part of the service-oriented architecture of the system for the “Wet Maatschappelijke Ondersteuning” (WMO) is simulated in BPEL. The goal is to provide a testing environment for new components that want to hook up to the WMO SOA. The components in the BPEL file are implemented by Java-based web services that reply to invocations with predefined test data. When one wants to test his or her new component implementation he or she should replace the corresponding web service with their own component. Using the same test data set as the simulation, the tester can now detect functional en semantical errors, without having to burdon the actual up and running SOA with these tests.