Executing Abstract Web Process Flows

Current business process flow representation languages such as BPEL4WS do not accommodate abstract specifications of business activities and dynamic binding of web services at run time. Moreover, dynamic selection of individual web services for a process is often not a stand-alone operation. There may be many inter-service dependencies and domain constraints that need to be considered in selecting legal and appropriate services for realizing an abstract flow. In this paper, we present a prototype workflow engine that accepts abstract BPEL4WS flows augmented with semantic annotations in DAML-S and performs runtime discovery, composition, binding and execution of web services. Building on prior work in this area [Mandel and McIlraith 2003], we provide a way of modeling and accommodating domain constraints and inter-service dependencies within a process flow. The result is a system that allows workflow designers to focus on creating appropriate high-level flows, while providing a robust and adaptable runtime.