Formal semantics and analysis of control flow in WS-BPEL

Web service composition refers to the creation of new (Web) services by combination of functionality provided by existing ones. This paradigm has gained significant attention in the Web services community and is seen as a pillar for building service-oriented applications. A number of domain-specific languages for service composition have been proposed with consensus being formed around a process-oriented language known as WS-BPEL (or BPEL). The kernel of BPEL consists of simple communication primitives that may be combined using control-flow constructs expressing sequence, branching, parallelism, synchronisation, etc. As a result, BPEL process definitions lend themselves to static flow-based analysis techniques. This report aims at validating the feasibility of using Petri nets for static analysis of BPEL processes. We present a comprehensive and rigorously defined mapping of BPEL constructs into Petri net structures. This leads to the implementation of a tool which operates by translating BPEL processes into Petri nets and exploiting existing Petri net analysis techniques. The tool performs two useful types of static checks and extracts meta-data to optimise dynamic resource management.