The Research of QoS Approach in Web Servers


  • Yansu Hu School of Automation Northwest Polytechnical University Xi’an 710072, China
  • Dejun Mu School of Automation Northwest Polytechnical University Xi’an 710072, China
  • Ang Gao School of Automation Northwest Polytechnical University Xi’an 710072, China
  • Guanzhong Dai School of Automation Northwest Polytechnical University Xi’an 710072, China


Web Server, Proportional Delay Guarantee, Feedback Control, Predictive Control


Proportional Delay Guarantee has been widely used in the Web QoS service, and the most basic methods are the feedback of control theory and the predictive control of queuing theory. While the former belonging to passive control has a long setting time and imperfect real-time, the latter can not simulate the Web server queuing system well because of the model limitations. After the experimental verification and shortages analysis of the two methods, an improved approach is proposed in this paper. Based on the queuing feature of Web server and the HTTP 1.1 persistent connection, the improved approach predicts the delay by calculating the queue length and service rate and achieves the relative delay guarantee of different classes by adjusting their quota of worker threads. The experimental results demonstrate that the approach could maintain the relative delay guarantees well even in poor network environment and performs a much better superior compared with the traditional methods.


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