Business Process Execution Language (BPEL) is a non-proprietary, XML-based language developed by a group of major vendors including IBM, BEA, and Microsoft. Its function is to describe how Web Services interact with one another to form workflow systems that implement business processes. As a model and grammar for describing this behavior, it lets you implement complex processes by creating and wiring together different activities such as invoking a service, manipulating data, throwing faults, or terminating processes. With BPEL you can take a structured top-down approach to implementing a Service-Oriented Architecture (SOA).