Adaptive schemes for distributed web caching

In distributed web caching architectures, institutional proxies take advantage of their neighbors' contents in order to reduce the number of requests forwarded to the server. Intuitively, the maximum benefit from this cooperation is expected when the proxies that exhibit similar requests are grouped together. The current practice is to follow a static and manual configuration of neighbors. Such an approach has a number of drawbacks: (i) static allocation may not determine the best neighbors, especially if global knowledge of the participating proxies is not available, (ii) a manual allocation places significant administrative burden, (iii) static schemes are insensitive to changes in access patterns, and (iv) they cannot deal with the introduction of new, potentially useful, proxies. In this paper, we propose a set of algorithms that allow proxies to independently explore the network for better neighbors and continuously update their configuration in an adaptive fashion. The simulation experiments illustrate that dynamic neighbor reconfiguration leads to significantly higher hit ratios compared to the static approach. Although some researchers in the past have recognized the need for adaptive caching, to the best of our knowledge this is the first study to propose concrete algorithms and evaluate their efficacy.