工作流异常处理的形式描述.pdf

第 40 卷 第 3 期 计 算 机 研 究 与 发 展 Vol40 ,No 3 2003 年 3 月 J OU RNAL OF COM PU TER R ESEA RCH AND D EV EL OPM EN T Mar 2003 工作流异常处理的形式描述 孙瑞志 　　　史美林 (清华大学计算机科学与技术系 　北京 　100084) (srzhi @csnet4 cst singhuaedu cn) 摘 　要 　异常处理是工作流执行中要解决的主要问题之一 ,清楚地描述异常处理的过程是最终得以实现的基础Petri net 对工作流的描述适合于对过程定义进行正确性验证和评价 ,但描述各种不同条件下的处理策略却很繁琐 采用了一 种直观的描述方法对异常处理过程中的元素 ,即活动 、异常事件 、异常处理策略以及处理措施进行了形式化描述 ,特别是 对不同处理策略下的处理过程进行了描述 结合消息机制 ,分析了一个异常事件出现时 ,如何处理一个活动实例产生的 中间数据 ,并对事务处理和异常处理的补偿策略进行了比较 描述方法为编码实现提供了很大的方便 关键词 　计算机支持的协同工作 ;工作流 ;异常处理 中图法分类号 　TP39309 Formal Presentation of Exception Handl ing in a Workflow System SUN RuiZhi and SH I MeiLin ( Dep art ment of Comp uter S cience an d Technology , Tsing hua University , B eij ing 100084) Abstract 　Exception handling is one of t he key issues t hat comp uter supported cooperative system must en counter Properly describing t he p rocedure of exception handling is helpful to designing and implementing t he funetions in a workflow management system Pet rinet is a app rop riate tool for validating t he correct ness of p rocess definition and giving evaluation But it is bur densome to describe a variety of p rocedures un der different conditions In t his p aper , t he handling element s including activities , exception event s , st rate gies , and met hods are described by means of an int uitional formal p resent ation , and especially t he handling p rocedures are described under different st rategies Wit h messagebased mechanism , t he temporary infor mation p roduced by t he interrupted activity inst ance is fir st analyzed and t hen how to p rocess information by formal p resent ation is described Finally , t he relationship in compensatory operations between exception handling and t ransaction p rocessing is illust rated The formal p res