Transforming process models : executable rewrite rules versus a formalized Java program

In the business process management community, transformations for process models are usually programmed using imperative languages. The underlying mapping rules tend to be documented using informal visual rules whereas they tend to be formalized using mathematical set constructs. In the Graph and Model Transformation communities, special purpose languages and tools are being developed to support the direct execution of such mapping rules. As part of our ongoing effort to bridge these two communities, we have implemented a transformation from petri-nets to statecharts (PN2SC) using both approaches. By relying on clear comparison criteria and by making the solutions available for online replay, we illustrate that rule-based approaches enable the transformation writer to focus on what the transformation should produce whereas imperative approaches require a more low-level specification involving element traversal algorithms. A mathematical formalization of such code not necessarily solves that problem. We therefore conclude that for developing mappings such as the PN2SC translation, the use of the GrGen language and tool is more appropriate