Abstract: To describe formal semantics of business processing execution language (BPEL) and BPEL for people (BPEL4People), the authors introduce the π_it-calculus, a new variant of the π-calculus. The execution of π_it-calculus can be interrupted and can handle timing events as well. Both syntax and semantics of the π_it-calculus are provided. A strong bisimulation relation that specifies when two processes can be considered as the same is also given. The activities of BPEL and BPEL4People are modeled by the new calculus. The formal framework may facilitate the reliability and consistency analysis in BPEL or BPEL4People design process.

Key words: BPEL, BPEL4People, π-calculus, timing, interruptable

摘要： 为了形式化地定义BPEL和BPEL4People的语义, 提出了一个π演算的变种??π_it演算。相对于传统的π演算, π_it演算可以描述中断事件和时间事件, 从而拥有更好的建模表达能力。介绍了π_it演算的语法和语义, 定义了一类强互模拟关系来判定π_it演算进程间的行为等价, 然后使用π_it演算对BPEL和BPEL4People的活动进行了建模。该形式化模型有助于在BPEL和BPEL4People程序的设计阶段对其可靠性和一致性进行验证。

关键词: BPEL, BPEL4People, π演算, 时序, 可中断