Dynamic replication of web contents

作者：Mahmood Amjad^*

来源：Science in China - Series F: Information Sciences , 2007, 50(6): 811-830.

DOI：10.1007/s11432-007-0018-5

• object replication
• Web
• distributed web-server system
• data placement
• Internet

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 general. In this paper, we consider the problem of placing copies of objects in a distributed 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 conditions 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.

• 出版日期2007-12