Web cache management based on the expected cost of web objects

Abstract

With the recent explosion in usage of the World Wide Web, Web caching has become increasingly important. However, due to the non-uniform cost/size property of data objects in this environment, design of an efficient caching algorithm becomes an even more difficult problem compared to the traditional caching problems. In this paper, we propose the Least Expected Cost (LEC) replacement algorithm for Web caches that provides a simple and robust framework for the estimation of reference probability and fair evaluation of non-uniform Web objects. LEC evaluates a Web object based on its cost per unit size multiplied by the estimated reference probability of the object. This results in a normalized assessment of the contribution to the cost-savings ratio, leading to a fair replacement algorithm. We show that this normalization method finds optimal solution under some assumptions. Trace-driven simulations with actual Web cache logs show that LEC offers the performance of caches more than twice its size compared with other algorithms we considered. Nevertheless, it is simple, having no parameters to tune. We also show how the algorithm can be effectively implemented as a Web cache replacement module.