Life Cycle

The model support by WSDL is a stateless client/server model using synchronous or uncorrected interaction. BPEL4WS, however, represents long-running transactions that are stateful in nature. In other words, they have a life cycle that extends well beyond a simple transaction. For example, a cable TV company gets an order, processes the work order, sends out an installer, does the installation, and begins billing the customer. This transaction could take weeks (sometimes months) and is long running. BPEL4WS is able to maintain the state of this process throughout the life cycle, keeping track of when the order came in all the way through to the billing activity. The use of the mechanism in the world of e-commerce is the most logical application, driving long-term durable transactions between trading partners. Coupled with the public versus private process features of BPEL4WS, it's clear that this is a process specification created for both internal and external use.

BPEL4WS can also create process instances, or many copies of the same process or subprocesses, as required to solve the business problem. When creating a process instance using BPEL4WS, the creation is implicit, thus activities that receive messages can be annotated to indicate that the occurrence of that activity creates a new instance of the process. To accomplish this, each business process should contain at least one "start activity." If one start activity executes, the use of correlation sets is not limited.

You can kill instances of business processes when the controlling business process completes, or when a fault reaches the process scope and is either handled or not handled, or when a process instance is explicitly terminated by a terminate activity. These are simple nesting-type constructs and should not be unfamiliar to most developers.



Next Generation Application Integration(c) From Simple Information to Web Services
Next Generation Application Integration: From Simple Information to Web Services
ISBN: 0201844567
EAN: 2147483647
Year: 2005
Pages: 220

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