The Design And Implementation Of A Workflow Engine Based On Petri Net

Workflow management system is a tool to realize Computer Support Collaboration Work, workflow of management functions could be implemented automatically or semi-automatically. It can make workflow by specification, to realize computer assistant control. Not only to benefit the standardization of work, but also convenient for the reasonable disposition of personnel and resource, the supervision, examination of workflow to improve working efficiency.Workflow engine is the kernel of the Workflow management system. It interprets the process description and controls the instantiation of processes and sequencing of activities, adding work items to the user work lists, invoking application tools as necessary, and providing supervision and management.First, the status of the research about workflow management system, workflow technology and basic concept of workflow, the reference model of Workflow Manage System interface, meta-model of workflow and the theory of Petri Net are analyzed. The Lightweight workflow engine based on Petri Net described by XML is designed according to five interfaces about WfMS, and implemented in Java. Clear structure and easy amendment are achieved by XML description. Adopting JAVA technology enables it has cross-platform feature.Process interpretation and loading module, process execution model, and database model are researched. The process interpretation and loading module is based on the theory of Petri Net and Workflow assembly model, workflow model based on XML is proposed. In the process execution model, the workflow instances execution principles and engine execution design, the design of the key classes and the parallel assembly routing algorithm are researched.Design patterns are adopted in the workflow engine several times. Through the introducing of design patterns, the program becomes readable, maintainable and useable. The application of BUILDER and STRATEGY combined with a project are analyzed.At the end of the paper, a management platform is taken as an example to show the three characteristics of the workflow engine. This project is one module of telecom"Number Know-all"system, which has been running in some area of country. First, Petri Net model is established, and the descriptive segment of XML is generated based on the operation flow of the project, then, execution effect of the parallel assembly is...