Priority is an important concept in Business Process Management (BPM), useful in the context of workflow patterns such as, e.g., cancelable and compensable tasks within business transactions. Unfortunately, the presence of priority in workflows makes them difficult to be analyzed formally by automated validation and verification tools. In the past, we demonstrated that the Reo coordination language can be successfully used for modeling, automatic validation and model checking of process models. In this paper, we propose a constraint-based approach to formalize priority in Reo. We introduce special channels to initiate, propagate, and block priority flows, define their semantics as constraints, and model priority propagation as a Constraint Satisfaction Problem (CSP). The semantic extension we propose in this paper enables workflow analysis in presence of priority constraints.

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Science of Computer Programming
Centrum Wiskunde & Informatica, Amsterdam (CWI), The Netherlands

Changizi, B., Kokash, N., Arbab, F., & Makhnist, L. (2021). Compositional workflow modeling with priority constraints. Science of Computer Programming, 203. doi:10.1016/j.scico.2020.102578