Reactive Petri Nets for Workflow Modeling

Petri nets are widely used for modeling and analyzing workflows. Using the token-game semantics, Petri net-based workflow models can be analyzed before the model is actually used at run time. At run time, a workflow model prescribes behavior of a reactive system (the workflow engine). But the token-game semantics models behavior of closed, active systems. Thus, the token-game semantics behavior of a Petri net-based workflow model will differ considerably from its behavior at run time. In this paper we define a reactive semantics for Petri nets. This semantics can model behavior of a reactive system and its environment. We compare this semantics with the token-game semantics and prove that under some conditions the reactive semantics and the token-game semantics induce similar behavior. Next, we apply the reactive semantics to workflow modeling and show how a workflow net can be transformed into a reactive workflow net. We prove that under some conditions the soundness property of a workflow net is preserved when the workflow net is transformed into a reactive workflow net. This result shows that to analyze soundness, the token-game semantics can safely be used, even though that semantics is not reactive.