Token Transportation in Petri Net Models of Workflow Patterns

In the context of runtime evolution of workflow processes, we present a Petri net based approach for pattern oriented workflow migration. In this approach a workflow process is seen as a composition of primitive workflow patterns. The paper demonstrates a yo-yo approach of token transportation in terms of the three primitive workflow patterns Sequence, AND, and XOR. Various cases of migration pairs of workflow patterns arising out of this choice are analyzed. The cases capture differences in pattern behavior and runtime token positions. As a result, modular generic token transportation bridges across patterns are finally formulated.