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.

优先级是业务流程管理（BPM）中的一个重要概念，在工作流模式（例如，业务交易中的可取消和可补偿任务）的上下文中很有用。不幸的是，工作流中优先级的存在使它们难以通过自动验证和验证工具进行正式分析。过去，我们证明了Reo协调语言可以成功地用于过程模型的建模，自动验证和模型检查。在本文中，我们提出了一种基于约束的方法来规范Reo中的优先级。我们引入了特殊的通道来初始化，传播和阻止优先级流，将其语义定义为约束，并将优先级传播建模为约束满足问题（CSP）。