Adding Preciseness to BPMN Models

BPMN is becoming the de facto standard for process description, analysis and simulation, in IT and many other business domains. BPMN supports different levels of abstraction, from high-level process models, to detailed models capable of being executed. Several tools now support, at least partly, OMG's BPMN metamodel specification. However, while several other OMG's metamodels include a formal specification of well-formedness rules, using OCL, the BPMN metamodel specification only includes those rules in natural language, scattered across several hundred pages of that document. Not surprisingly, we found that all mainstream BPMN tools do not enforce those well-formedness rules, while checking the correctness of process models. Model preciseness enforcement is important to mitigate ambiguity. The latter hampers the achievement of a shared meaning among process stakeholders, is detrimental to process reuse and is unacceptable if we look for executable processes. To enforce model preciseness we propose to supplement the OMG BPMN metamodel with well-formedness rules expressed as OCL invariants.