Business Process Lifecycle

A business process specified in BPEL has a well-defined structure. It usually waits for the client to invoke the process. This is done using the <receive> activity, as we have seen in the previous chapter. A business process can also use the <pick> activity to wait for the initial incoming message. Then the business process typically invokes several operations on partner web services and waits for partners to invoke callback operations. The business process also performs some logic, such as comparison and calculation of certain values. The business process terminates after all activities have been performed.

We can see that each BPEL process has a well-defined lifecycle. To communicate with partners BPEL uses web services. Web services provide a stateless model for operation invocation. This means that a web service does not provide a common approach to store client-dependent information between operation invocations. For example, consider a shopping...