Selective Update Approach to Maintain Strong Web Consistency in Dynamic Content Delivery

Zhou SU  Masato OGURO  Jiro KATTO  Yasuhiko YASUDA  

IEICE TRANSACTIONS on Communications   Vol.E90-B   No.10   pp.2729-2737
Publication Date: 2007/10/01
Online ISSN: 1745-1345
DOI: 10.1093/ietcom/e90-b.10.2729
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Section on New Challenge for Internet Technology and its Architecture)
content delivery networks,  consistency algorithm,  web cache performance,  network traffic,  

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Content delivery network improves end-user performance by replicating Web contents on a group of geographically distributed sites interconnected over the Internet. However, with the development whereby content distribution systems can manage dynamically changing files, an important issue to be resolved is consistency management, which means the cached replicas on different sites must be updated if the originals change. In this paper, based on the analytical formulation of object freshness, web access distribution and network topology, we derive a novel algorithm as follows: (1) For a given content which has been changed on its original server, only a limited number of its replicas instead of all replicas are updated. (2) After a replica has been selected for update, the latest version will be sent from an algorithm-decided site instead of from its original server. Simulation results verify that the proposed algorithm provides better consistency management than conventional methods with the reduced the old hit ratio and network traffic.