Dynamic replication of web contents

作     者：Amjad Mahmood 

作者机构：Department of Computer Science University of Bahrain Kingdom of Bahrain 

出 版 物：《Science in China(Series F)》 (中国科学（F辑英文版）)

年 卷 期：2007年第50卷第6期

页      面：811-830页

核心收录：

学科分类：08[工学] 080402[工学-测试计量技术及仪器] 0804[工学-仪器科学与技术] 

主　　题：object replication Web distributed web-server system data placement Internet 

摘      要：The phenomenal growth of the World Wide Web has brought huge increase in the traffic to the popular web sites. Long delays and denial of service experienced by the end-users, especially during the peak hours, continues to be the common problem while accessing popular sites. Replicating some of the objects at multiple sites in a distributed web-server environment is one of the possible solutions to improve the response time/latency. The decision of what and where to replicate requires solving a constraint optimization problem, which is NP-complete in gen- eral. In this paper, we consider the problem of placing copies of objects in a dis- tributed web server system to minimize the cost of serving read and write requests when the web servers have limited storage capacity. We formulate the problem as a 0-1 optimization problem and present a polynomial time greedy algorithm with backtracking to dynamically replicate objects at the appropriate sites to minimize a cost function. To reduce the solution search space, we present necessary condi- tions for a site to have a replica of an object in order to minimize the cost function. We present simulation results for a variety of problems to illustrate the accuracy and efficiency of the proposed algorithms and compare them with those of some well-known algorithms. The simulation results demonstrate the superiority of the proposed algorithms.