【作者】 刘丹妮；

【导师】 唐达；

【作者基本信息】 大连理工大学 ， 计算机应用技术， 2005， 硕士

【摘要】 时间问题是一个企业提高效率和信誉的重要因素。因此,时间的验证与分析成为当今工作流研究的一个热点问题。在一个实际的工作流中,常常有一些可跨越活动和可替换路径,对可跨越活动适当取舍和可替换路径适当选择,会提高截止期限被满足的可能性。并且,在执行过程中,人们往往关心某些状态是否存在可达性,以及处理结果产生的最迟时间——截止期限。目前对工作流建模主要采用工作流图和petri网,普遍存在的问题是当系统中结点过多时,容易引起状态爆炸。 为了解决上述问题,本文介绍了一种基于工作流图的时间模型,提出了使用四种关键路径对工作流截止期限进行动态验证的方法。这种方法不必计算所有活动实例的截止期限,只需根据实际需要,针对部分实例计算,减少计算量,提高了工作流的执行效率。在一个实际的工作流中,常常有一些可跨越活动和可替换路径,对可跨越活动适当取舍和可替换路径适当选择,会提高截止期限被满足的可能性。 对活动增加截止期限的约束条件并验证可达情况,是人们在实际应用中对工作流系统提出的新要求。本文提出了一种基于层次时间petri网的工作流模型。在基于TPN的工作流模型中增加截止期限约束条件,并将各个路由结构按照给出的规则分层提取,得到只有顺序结构的HTPN模型。模型转化的同时进行了物理可达性的验证;给出层次时间树算法,利用得到的层次时间树对活动进行静态和动态时间验证。 在理论研究基础上,以FlexWork系统为背景,将上述两种时间验证思想相结合,利用层次划分思想在建模阶段进行物理可达性验证,采用关键路径进行时间静态和动态可达性验证,开发了一个工作流管理系统,理论研究成果在该系统中得到了较好的应用。更多还原

【Abstract】 There are some optional activities and alternative paths. Deadline will easily satisfy by utilizing them. When the workflow works, people focus on status which will be reached or and the deadline. The main methods of modeling are workflow graph and petri net. When there are many nodes, status eruption may happen.In order to estimate the latest finishing time of an activity node, a temporal model based on workflow graph is introduced. Then we propose four kinds of critical paths, which are used to verify the deadline of the workflow. By the method, we don’t need to calculate the deadlines of all the activities, but only to calculate some of them, according to the facts. The method reduces calculation, and improves the execution efficiency of workflow.The deadline of activity and reachability verification have been recognized as one of the most significant time limitations of today’s workflows. In this paper, a new temporal model , hierarchically timed petri net (HTPN), is proposed through incorporating the deadline constraints into TPN. We present rules to fetch structures hierarchically. While TPN is converted to HTPN, physical reachability is verified. An algorithm of hierarchically timed tree is put forward. Then, the method of verifying the timing reachability is given. We demonstrate the application of our method with an example.On the foundations of theoretical research, we have developed a workflow management system. This system is Flex Work based on the B/S three layers structure. In some distance, this system has performed the productions of the theoretical research.更多还原