Study And Implementation Of A Hierarchal Workflow Simulation Model

Workflow simulation has become a new hotspot in workflow study, as workflow technology is growing into maturity. But the relative achievement is poor, because the study on workflow simulation was going on few times ago.This paper presents a hierarchal workflow simulation model based on the theory of discrete event dynamic system (DEDS) simulation. A simulation system has been realized based on this model and integrated into our distributed workflow infrastructure system (WFIS). This model is distributed into three layers. The bottom layer is DEDS simulation layer; the second layer is dynamic simulation of workflow process-model; the top layer is analysis of simulation results. And the DEDS simulation layer is used as the basic of workflow simulation layer, and will be called by workflow simulation layer. The analysis layer takes charge of collecting and stating simulation data which the second layer produced. This kind of hierarchy makes these layers have relationships with each other but also keep their separateness. As a result, this hierarchy will help us to alter one layer but not have to concern about another one. Therefore a loose coupling between these layers is made up.This simulation system allows business process-model to be simulated through setting up simulation conditions. At the end of simulation, many statistical data would be provided for users to analyze performance indexes of this process-model, and then to improve the process-model.The paper firstly introduces some base knowledge of workflow simulation, which includes: intro of workflow management system(WFMS); intro of the integration between workflow simulation system and WFMS; intro of simulation's meaning and processes. And then the theory of DEDS simulation is analyzed, which is the foundation of system realization, including the base strategy and some common simulation-model. Accordingly a hierarchal workflow simulation model is brought forward, including its structure and the mechanism of its realization. Finally, we introduce the design and implementation of a workflow simulation system based on this hierarchal simulation model.