Performance Analysis Of Computer Networks And Design Of Electronic Commerce Models Based On Petri Nets Theory

Performance analysis of computer networks and modeling electronic commerce system are two important researching subjects in the field of computer networks. In this paper, we mainly research and analyze performance analysis of TCP networks and buyer/seller design in electronic commerce. The performance of TCP networks and its relative problems are important researching subjects. This dissertation presents our outcomes of performance analysis of the operation mechanism of TCP networks based on petri nets theory. In the meanwhile, we further study the Performance of interworking unit between TCP/IP LANs and ATM trunk. Because electronic commerce is one of the important applications of computer networks, we research the seller/buyer modeling in electronic commerce based on petri nets in this paper.The main work of this dissertation are listed as follows:We introduce several main modeling mathematical tools of computer networks and compare and analyze these mathematical tools from the starting point that there are contradictions between modeling of computer networks and solving the model. We analyze the relations between stochastic Petri nets and basic stochastic process, and discuss the solution to various stochastic petri nets.According to the relativity among TCP connections sharing one bottleneck link and the dynamics of the TCP window, we present the multi-user model and single-user model of TCP network, and solve these two models through iterative algorithm. In order to verify our modeling approach, we compare the model's results with the output of the famous simulator ns2. The results show that our GSPN model of TCPlvnetworks can accurately estimate the performance of TCP connections under several given network parameters.We model the buffering mechanism of interworking unit with permanent virtual connection through M/M/1/K queuing approach and solve this model. Next, under the same conditions as queuing model, we present the GSPN model of interworking unit. In the meanwhile, we analyze the relations between setup and releasing of connections and performance of model. Finally, we present the DSPN model of interworking unit on the basis of considering the bursting characteristic of data flow of IP LANs and adopting the deterministic transitions which are more close to reality of setup and releasing of connections. We solve the DSPN model with TimeNET.An Object-Oriented Agent Petri Nets (OAP) is proposed in order to design the buyer/seller models in electronic commerce. This OAP model has not only the characteristics of object-oriented technology and Petri nets, but also the characteristics of agent system. Besides, asynchronous communication and synchronous communication can be achieved in the OAP model through the interfaces among buyer models and seller models. In this dissertation, we design the buyer (people who want to buy house) model and seller (developer of real estate) model of dealing in real estate in electronic commerce with OAP technology according to contract net protocol. Finally, we illustrate the live~ concurrent and effective properties of our models.Finally, the author makes a conclusion and proposes some further research directions.