Pattern-based Translation of BPMN Process Models to BPEL Web Services

The Business Process Modelling Notation (BPMN) is a graph-oriented language in which control and action nodes can be connected almost arbitrarily. It is primarily targeted at domain analysts and is supported by many modelling tools, but in its current form, it lacks the semantic precision required to capture fully executable business processes. The Business Process Execution Language for Web Services (BPEL) on the other hand is a mainly block-structured language, targeted at software developers and supported by several execution platforms. In the current setting, translating BPMN models into BPEL code is a necessary step towards standards-based business process development environments. This translation is challenging since BPMN and BPEL represent two fundamentally different classes of languages. Existing BPMN-to-BPEL translations rely on the identification of block-structured patterns in BPMN models that are mapped into block-structured BPEL constructs. This paper advances the state of the art in BPMN-to-BPEL translation by defining methods for identifying not only perfectly block-structured fragments in BPMN models, but also quasi-structured fragments that can be turned into perfectly structured ones and flow-based acyclic fragments that can be mapped into a combination of block-structured constructs and control links. Beyond its direct relevance in the context of BPMN and BPEL, this paper addresses issues that arise generally when translating between graph-oriented and block-structured flow definition languages.