Web System Modeling And Performance Evaluation

With the development of Internet, Web- World Wide Web(WWW) 's applicable field become more extensive, the progress of technology tends to be diversified. For the quickly increasable web users, Web must provide more reliable and high quality services, so it can keep up with the development. It is a very important research field for the web system performance evaluation. Based on deeply analyzing and mastering current research state at home and abroad, using the mathematic theory of queueing and queueing network, modeling the large web cluster system, modeling the basic platform of the multi tier web application, modeling the web application. The system's expressions of performance measures are obtained from simulation and tests. Through comparing and analyzing, the system's optimal results are presented, which provides theoretical basis and analysis methods for the web system performance planning and Web application designing.Firstly, by adopting the queue model of M/G/1, the optimal establishing policy of the cluster system are presented, considering the servers performance and server number simutaniously; Through the transition of complex queueing network model, by analyzing based on the M/M/c queue model, the range of optimal server number of the cluster are obtained; By adopting the M/M/c queue model with vacations, the optimal power management policy of the cluster are presented; from simulation, performance evaluation is done for the cluster's load balancing policies. Numerical analysis and validation is done for these models.Sencondly, based on the running enviroment of the multi tier web application, models are presented for web server, application server and database server respectively. Through queueing network analyzing, integrating the system tests, the optimal configuration policy of the sevice platform's establishment are presented. For web's basic network platform, queueing network model is given. By adopting the MVA algorithm and diffussion approxmimate algorithm of queueing network, the performance expressions are obtained. By comparision with simulation of NS-2, system's bottleneck is analyzed and improved policies are presented. Thirdly, queueing network analysis is done to the large scale J2EE application established in server clusters and small J2EE application on sharing hosts. Model's accuracy is validated from tests. The system optimal establishment policy is presented. For the composite web services, a marchov chain model is established according to the parelell relationship. A queueing network model is established according the complex composite relationship, Solving and numerical analysis are done respectively. System optimal establishment policy is presented. Through transition for web application's UML model, by analyzing from layered queueing network, according to the MVA algorithm of layered queueing network, some performace indices of the application are obtained, so performance prediction are done to the software.Finally, through analyzing of response time and traffic flow of AJAX of the instances of web application, actual optimal performance policies are presented for the web application, simple analysis for other performance indices are also presented.