Extending Web Service Flow Models to Provide for Adaptability

Web Service compositions combine characteristics of both the Web service (WS) and workflow technologies. The workflow technology is good at explicitly defining integration logic. Web services bring in standardized service description and communication over the Web, and thus provide for seamless integration across organizational boundaries. The two technologies mutually amplify their benefits in this combination. Nevertheless, WS compositions (WS-flows) inherit also some of the deficiencies both technologies exhibit. Notably, traditional workflow technologies lack sufficient support for workflow adaptability, which is a prerequisite for ensuring business processes flexibility. In this paper we argue that any standardization activity in the field of WS-flows must gravitate around a unified process meta-model. Additionally, adaptability should be considered as an inseparable part of the WS-flow meta-model constructs. We propose process meta-model extension constructs that accommodate WS-flow adaptation in implementation independent manner. The presented constructs allow for run time modifications of participating WS instances and WS types, and changes in business logic.