摘要：Traditional workflow models have obvious shortcomings in describing complex workflows. Such complexity is due not only to the hierarchical property of business process, but also to the complicated dependencies among tasks. In this paper, we first introduce a conceptual task model based on UML class graph. Then we apply colored Petri nets to model task interfaces and composite task versions which form Task State Nets (TSNs) and Task Version Nets (TVNs). The main advantage is that they explicitly express all task interfaces' internal states and thus they can easily describe the complex control dependencies. Next we further combine TSN/TVN with place refining mechanism and bring forward our Hierarchical Task State Net (HTSN). It supports the description of workflow's hierarchical structure, multi-versions configuration of composite task as well as the analysis of structural properties. Finally, we give a case study
关键词：Complex workflow; Colored Petri net; Task ;State Net; Task version; Hierarchical Task State Net
