Enhancing BPEL scenarios with Dynamic Relevance-Based Exception Handling

Abstract

Web services have become the key technology in business processes management. Business processes can be self-contained or be composed from sub-processes; the latter category is typically specified using the Web services business process execution language (WS-BPEL) and executed by a Web services orchestrator (WSO). During the execution however of such a composite service, a number of faults stemming from the distributed nature of the SOA architecture, e.g. network or server failures may occur. WS-BPEL includes provisions for exception handling, which can be exploited for detecting such failures; once detected, a failure can be resolved by invoking alternate Web service implementations that perform the same business task as the failed one. However, the inclusion of such provisions is a tedious assignment for the business process designer, while additional effort would be required to maintain the BPEL scenarios in cases that some alternate WS implementations cease to exist or new ones are introduced. In our research we are developing a framework for automating handling of that kind of exceptions. The proposed solution employs a pre-processor that enhances BPEL scenarios with code that detects failures, discovers alternate WS implementations and invokes them, fully thus resolving the exception. Alternate WS implementation discovery is based on service relevance, which takes into account both functional and qualitative properties of Web services.