Research And Implementation Of Web Service Composition Exception Resolution Based On BPEL

WS-BPEL is widely used nowadays for specifying and executing composite business processes within the Service Oriented Architecture (SOA). During the execution however, of such business processes, when invoking Web services, a number of faults resulting from the nature of SOA (e.g. network or server failures) may occur. And these faults will make the BPEL loose there track。The WS-BPEL scenario designer must therefore use the provisions offered by WS-BPEL to catch these exceptions and resolve them, usually by invoking some equivalent Web service that is expected to be reachable and available. However, this method introduces new problems when it comes to ensuring superior performance and availability.In this paper, the research is based on one of the national 863 project which is high reliability software production line's sub project the BPEL engine's design and realization, focus on the exception handing problems, the main works are as follows:1. In this paper, we propose a middleware-based framework for system exception resolution, which undertakes the tasks of failure interception, discovery of alternate services and their invocation. The middleware is deployed and maintained independently of the WS-BPEL scenarios, removing thus the need for specifying and maintaining system fault handlers within the scenarios.2. The process of selecting the alternate services to be invoked can be driven by process consumer specified QoS policy, specifying lower and upper bounds for each QoS attribute as well as the importance of each QoS parameter. This method has conceded the process user's needs, and can make the process adapt to the changing of the consumer's demand.3. Moreover, the middleware arranges for bridging syntactic differences between the originally invoked services and functionally equivalent replacements to it, by employing XSLT-based transformations.4. In this paper, we explained the framework which introduced in this paper, and realized the framework too. We also analysis this framework's performance by experiment.