The Business Process Execution Language (BPEL) industry standard supports the specification and execution of business processes implemented as a composition of web services defined by the Web Service Definition Language (WSDL) interfaces. As BPEL adoption increases, business analysts and developers are confronted with the challenges of developing BPEL applications. A key challenge is the difficulty in simulating BPEL processes due to the unavailability of one or more of web services involved in the business process workflow. BPEL simulations have many uses. This thesis describes an Eclipse-based tool that generates a collection of realistic synthetic XML messages to simulate the existence of web services participating in a BPEL process (including support for message correlation). The tool leverages the ToXgene XML generator, WSDL tools from the Eclipse WTP project together with a concise semantic description of the desirable properties of the data to be generated.