Towards the Semantics and Verification of BPEL4WS

In this paper, we discuss the semantics of BPEL4WS language which is a de facto standard for specifying and execution workflow specification for web service composition and orchestration. For the convenience, We propose the language called μ-BPEL including all primitive and structured activities within BPEL4WS. Moreover, As the Timed Automata (TA) [2] is powerful in designing real-time models with multiple clocks and has well developed automatic tool support the verification, we define and map BPEL4WS constructs into composable Timed Automata. Therefore, all the properties we want to check within BPEL4WS can be verified in TA network correspondingly. Furthermore, we prove the mapping from μ-BPEL to TA is a simulation which means the TA network simulates correctly the corresponding specification written in BPEL4WS. The case study in Uppaal model checker shows that our method is effective, and a Java supporting tool based on Uppaal model checker engine has been developed.