Modeling And Performance Analysis For Web System Based On Timed Colored Petri Nets

Along with swift development and extensive application of the Web system, the function validation and performance improvement is more and more being focused. Therefore the development of Web system becomes a hard and complicated work. The developers want to make it possible that function validation and performance analysis can be done in the forepart so that they can discover the bug of design and take action to improve the performance of the Web system. Therefore, it is very important to model and analyze Web system.Many scholars take up with study of modeling and simulation of Web system and bring forward a lot of formalization methods which have been used into modeling and performance analysis, such as Queuing Network, Stochastic Petri Net, Stochastic Process Algebra, Colored Petri Net etc. The calculating processes of SPA, SPN and QN use the Markov chain. Because of the existence of state space explosion, it is very difficult and even impossible to translate a little system into a mathematical analyzing model. SPN has stronger ability to describe the model especially to analyze the performance of distributed systems, parallel systems and synchronous systems etc. However, as the increase of place, transition and token state space explosion still exists. Colored Petri net is a graphical tool being used to model and analyze the system performance, which especially adapts to describe sequence, concurrence, synchronization and conflict, can depict the static structure and analyze the dynamic behavior of system. Colored Petri net has both intuitionistic graphic description and profound mathematic foundation, which model can be validated and analyzed by some mathematical tool such as Markov chain. This paper considers an advanced Petri net, timed colored Petri net (TCPN), to establish more accurate Petri net model. TCPN is more effective to depict and analyze synchronization, communication and resource share of concurrence manipulations which occur in the model based on time. Therefore, it greatly adapts to model and analyze complicated Web system. This paper mainly fastens on improving the process of the Web system, modeling by TCPN and the performance analysis of the TCPN model. The main work of this paper is as follows:1. We analyze the characteristics of classical Petri net and hierarchical CPN, and we investigate the dynamic properties and the modeling advantage of TCPN. The performance analysis method of CPN Tools is studied.2. We study the mechanism and working process of the Web system from theory aspect. We adequately use the function of TCPN being good at simulating working processes to analyze the possible mistakes of the process and how to discover and modify them.3. We carry out the TCPN model of the Web system. Through a case in which we use function validation by state space and performance analysis by Monitor to investigate the login of user information and response process we realize the improvement of Web system process and enhance the performance of Web system.