The Management Of Time And Resource For Nondetermined Workflow Based On Petri Nets

The management of workflow is one of the hotspots in the field of computer application. Many modeling approaches have arisen, in which Petri net is one of the important and practical approaches for the modeling of workflow. Time and resource are two important aspects in workflow system. At present, the time and resource management of workflow based on Petri net have been researched deeply, the workflow constrained by time and resource is widely used in real life.At present, the research works of nondetermined workflow mainly focus on the duration time of activities. This thesis introduces a kind of nondetermined workflow. This kind of workflow considers both the nondertermined duration time of activities and the nondertermined preparation time of resources. Thus, this thesis does some research in the following aspects.First, the definition and the modeling approach of nondetermined workflow(NTA/R_WF) is given. The definition of nondetermined workflow(NTA/R_WF) is given and the Petri net model of NTA/R_WF is addressed, then the modeling approach for the workflow is obtained.Second, a set of reduction rules are introduced to reduce the scale of the NTA/R_WF_Net model from the aspects of nonreused resource and reused resource. It can be proved that the reduction rules keep time and resource constraints invariant in the workflow and don't influent the finish time of the workflow. The model is more simple and easy to understand and analyze after reduction.Thirdly, the methods of analyzing the time performance and resolving the resource conflict resolution are proposed. We analyze the key activities and the key line influencing the time to finish the workflow, then a resource conflict resolution—KAPS (key-activity priority strategy) and WSPS (waiting-short priority strategy) is introduced. This method can resolve the conflicts of both the nonreused resource and the reused resource. Though this resolution, the earliest and latest time to finish each activities is obtained. At last, the definition of resource conflict is given and four resolutions to remove resource conflict are introduced. This thesis takes a workflow for production manufacture and sale system and a workflow for architectural decoration system as examples to demonstrate the process of modeling, reduction, time analysis and the resource conflict resolution given in this thesis.