Formal Model of Web Service Composition: An Actor-Based Approach to Unifying Orchestration and Choreography

摘要

Web Service Composition creates new composite Web Services from thecollection of existing ones to be composed further and embodies the addedvalues and potential usages of Web Services. Web Service Composition includestwo aspects: Web Service orchestration denoting a workflow-like compositionpattern and Web Service choreography which represents an aggregate compositionpattern. There were only a few works which give orchestration and choreographya relationship. In this paper, we introduce an architecture of Web ServiceComposition runtime which establishes a natural relationship betweenorchestration and choreography through a deep analysis of the two ones. Then weuse an actor-based approach to design a language called AB-WSCL to support suchan architecture. To give AB-WSCL a firmly theoretic foundation, we establishthe formal semantics of AB-WSCL based on concurrent rewriting theory foractors. Conclusions that well defined relationships exist among the componentsof AB-WSCL using a notation of Compositionality is drawn based on semanticsanalysis. Our works can be bases of a modeling language, simulation tools,verification tools of Web Service Composition at design time, and also a WebService Composition runtime with correctness analysis support itself.