Chapter 4. Advanced BPEL

In the previous chapter, we covered the basics of BPEL and provided an introduction to the structure of business processes. We are now familiar with defining business processes, invoking web service operations sequentially and in parallel, defining partner links, defining variables, and assigning values. However, using BPEL for complex real-world business processes requires additional functionality. Sometimes the activities of a business process need to be performed in loops. Often activities might have links that would affect the execution order. This is usually the case with concurrent flows. Sometimes we will have to wait either for a message event or an alarm event to occur.

One very important aspect of business process modeling is fault handling. Particularly in business processes that span multiple enterprises and use web services over the Internet, we can assume that faults will occur quite often due to various reasons, including broken connections, unreachable...