Transform BPEL Workflow into Hierarchical CP-Nets to Make Tool Support for Verification

Availability of a wide variety of Web services over the Internet offers opportunities of providing new value added services by composing existing ones. Service composition poses a number of challenges. A composite service can be very complex in structure, containing many temporal and data-flow dependencies between the component services. It is highly desirable therefore to be able to validate that a given composite service is well formed: proving that it will not deadlock or livelock and that it respects the sequencing constraints of the constituent services. In this paper, we propose an approach of composition analysis and verification based on Colored Petri nets (CP-nets), which is an extended version of Petri Nets, which have a sound mathematical semantics and a number of existing analysis tools. We provide translation rules of web composition language into CP-nets and a technique to analyze and verify effectively the net to investigate several behavioral properties. Our translation technique is essentially independent of which language we describe composition. As an example, to show the effectiveness of our technique, we pick up BPEL and translate the BPEL specification into CP-nets in a constructive way. These nets are analyzed and verified as prototypes of the specification.