Research On Verification Of Workflow Model Based On Directed Hypergraph

Workflow technology is an important computer technology to realize automation management of enterprise business process. In order to solve the verification problem of workflow structure, this thesis introduced firstly the related concepts of workflow technology and current research status, then clarified the hazards of using workflow model with errors and the need of verification before applying a workflow model to a workflow system. Summarized current research results on workflow structure verification and three major verification methods of workflow model: WF-NET method,Method based on Pi Calculus,Reduction and replacement method. Based on above research, we provid a new verification method of workflow model based on directed hypergraph.Due to directed hypergraph's mathematical foundation and rigorous formal analysis ability, it can describes clearly the relationship of many-to-many, one-to-many,and many-to-one. In the process of workflow modeling by using the directed hypergraph method, we can omit Pseudo-nodes such as Split-AND,Join-AND,Split-OR,Join-OR, reduce model's elements to make the model more concise and more easy to understand. Based on directed hypergraph's characteristic, the principle of workflow model mapping to directed hypergraph is provided, and then the workflow model based on directed hypergraph was built.The workflow model's structure errors, such as deadlock and lack of synchronization, and corrsponding reasons were clarified, and a new workflow model verification method based on directed hypergraph is proposed. The method first build an instance subgraph for each branch of Split-OR, then search the instance subgraph based on Left-most and Depth-most principles to find the errors existence or non-existence in the workflow model.Using an enterprise IT department's purchasing process model to illustrate the operation steps of the verification method based on directed hypergraph. Results have shown that the deadlock and lack of synchonization existed in the workflow model can be identified.A workflow model verification tool-WF Editor is developed. A purchasing model of an enterprise's IT department is used to verify the proposed method's validity, the structure errors in the model such as deadnode,deadend,unreachable goal,deadlock and lack of synchronization were found. The results show that the method is effective.