A Novel Approach to Decentralized Workflow Enactment

Abstract

Web service orchestrations-expressed in the Web service business process execution language (WS-BPEL or BPEL for short)-are a manifestation of the two-level-programming paradigm where services, i.e. the business functions used by the composite application, are composed through BPEL's control flow constructs. BPEL processes Web service orchestrations, business functions therefore can be transparently accessed remotely, allowing to build composite applications that integrate business functions provided by different partners on different locations. As of today, execution of BPEL processes, i.e. the evaluation of the processes' control flow, is performed by a central workflow engine. In certain scenarios, such as complex collaborative cross-partner interactions, this approach of centralized workflow enactment leads to "un-natural" process models; process models that are not driven by the processes' original business goal but by infrastructural or organizational reasons. In this paper, we propose an alternative approach to enacting BPEL process control flow in a distributed, decentralized manner. We present the overall process lifecycle and give a detailed description of the underlying process model.