Timed Petri Net-based Work Flow Model

As an effective support tool for process modeling, optimization analysis, business process automation, workflow technology to become a famous technology in recent years which is widely applied,strong researched and is rapid developmented in industry. In recent years, as companies'increasingly fierce market competition and changing business environment, the requirements of business process management and optimization become more and more. Among them, the time management of workflow system plays an important role.To achieve the time management of workflow, first of all is how to solve the formal way to describe the time information and time behavior. With intuitive graphical representation, clear semantics, solid theoretical foundation, abundant analysis techniques and be suitable to describe the characteristics of discrete parallel systems,Petri net, is considered the most promising methods of workflow modeling, and based on it, W. M. P. van der Aalst proposed workflow net. It has been proposed a variety of model based on the extended Petri nets which are described the time in workflow. This study was done on expansion and improvement of workflow model based on time Petri net.This paper firstly introduces the basic theory of workflow and Petri nets, and then analyzed the workflow net and the general time workflow net, and with an example, the shortcomings of general time workflow net in the definition of time information is elaborated.The first core component of this study is the time information definition in time workflow model. The time information in the general time workflow net includes time constraints of activity (enabled time, the fired time) and execution delay of activity. However, the information is still not enough to describe the complex time information of workflow. To address its shortcomings in the incomprehensive definition of time information, this paper add valuable time of token, valuable time of transition and time limit of overall process to the general time workflow net, Advanced Time Workflow-net(ATWF-NET) model is formed. And an example of ATWF-NET modeling and analysis show that the model can effectively solve the shortage of TWF-NET, can clearly describe the business processes with complex time information.The second core component of this study is the presentation of time information in the time workflow model. With the development of workflow applications, it is common that the time information is becoming increasingly uncertain; it has become new one of the difficulties in time modeling and analysis of workflow. To address the uncertainty of the time model, based on previous studies, this paper introduces the concept of fuzzy time to time to improve workflow net model, created ATWF-NET model based on fuzzy time, And detailed definite the modeling of time information in the workflow model and calculation of the time possibility of whole workflow. Finally, this paper gives an example to prove FATWF-NET can more completely describe the workflow system which has resources and activities with uncertain time constraints.