On Modeling and Verification of Temporal Constraints in Production Workflows

The dynamic nature of events, in particular business processes, is a natural and accepted feature of today’s business environment. Therefore, workflow systems, if they are to successfully model portions of the real world, need to acknowledge the temporal aspect of business processes. This is particularly true for processes where any deviation from the prescribed model is either very expensive, dangerous or even illegal. Such processes include legal processes, airline maintenance or hazardous material handling. However, time modeling in workflows is still an open research problem. This paper proposes a framework for time modeling in production workflows. Relevant temporal constraints are presented, and rules for their verification are defined. Furthermore, to enable visualization of some temporal constraints, a concept of “duration space” is introduced. The duration algorithm which calculates the shortest/longest workflow instance is presented. It is a generalization of two categories of algorithms: the shortest-path partitioning algorithm and the Critical Path Method (CPM). Based on the duration algorithm, the verification algorithm is designed to check the consistency of introduced temporal constraints.