An Operational Approach to BPEL-like Programming

Web services have become more and more important during these years and BPEL4WS (BPEL) is to be a standard for the Web services composition and orchestration. It contains several distinct features, including the scope-based compensation and fault handling mechanism. In this paper, we formalize an operational semantics for BPEL, which provides the precise understanding of the language. In order to explore program equivalence, bisimulation is introduced for BPEL pro grams in the form of two-layer structure. A set of algebraic laws is studied, which includes several BPEL featured laws. These algebraic laws are verified via the two-layer bisimulation. This reflects that our bisimulation is a practical approach to explore program equivalence for Web services.