ReFFlow: A Model and Generic Approach to Flexibility of Web Service Compositions

This paper addresses two important aspects of Web service compositions on the one hand, flexibility of Web service (WS) compositions, and on the other the automatic development of such compositions. The existing WS composition models and languages do not support process adaptability at run time. In this respect we propose to extend the existing models with generic constructs to accommodate dynamic features of processes that ensure adaptability. The proposed constructs enable swapping instances of participating Web service and changing process schema at run time. The ultimate goal is to define a unified WS composition model that enables the development of portable process definitions with built-in flexibility. We focus on such a process model that does not impose any specific implementation approach. The second major issue we address is the automated development of WS compositions. A prerequisite for the automated development is the availability of a process model. Additionally, WS-flows templates can be used to promote reusability and automation further, and can be classified for specific business domains.