Client-Side Content Delivery Policies in Replicated (Performance Evaluation Journal)

Several techniques have been developed to address web-service reliability, and to provide a better QoS for Internet users. A relatively new technique is Web services geographical replication. Geographical replication can be achieved with both server-side and client-side policies. Among these policies, in this paper we contrasted, qualitatively and quantitatively (via simulation), the most promising client-side techniques: one parallel strategy and one single-server strategy. The aim of our study was to determine the pros and cons of the two approaches. We analytically quantified the overhead introduced by the selected parallel strategy and proposed two extensions of the parallel strategy to reduce its overhead still maintaining the simplicity of the original approach. Results of our analysis pointed out the problems of adopting a parallel strategy in a widespread fashion, and indicated the scenarios in which a parallel strategy may be advantageous. As a result of our study we proposed a hybrid strategy that combines the parallel and the single server strategies.