Policy based Web Service Orchestration and Goal Reachability Analysis using MSC and CP Nets

Specification of a Web services-based process (WSP) for a complex environment such as homeland security domain is a complex task. The specification task requires achieving a balance between intuitive and easy to understand process representation for the interactive domain user and consolidated formal specification. An easy to understand process representation facilitates conformance of process correctness where as the formal specification ensures formal goal reachability analysis of service orchestration for executing the process. Existing approaches provide means for service orchestration and invocation, however, there is little to support the specification and goal reachability analysis of WSPs representing distributed service oriented architectures. In this paper we present a novel approach to service orchestration that combines an effective diagrammatic modeling, an appropriate formal framework and an implementation process for dynamic WSP and complex Web service composition and goal reachability analysis. Specifically, our approach for WSP specification and goal reachability analysis comprising of service orchestration using high level message sequence charts (HMSC) and Colored Petri Nets (CP Nets) provides a methodology for instantiation of the general WSP that is specific to individual users. The process instantiation takes in to account the dynamicity aspects in terms of the changes in the domain requirements, the user request and the component services that form the WSP.