Hk/T:: A novel server-side Web caching strategy for multimedia applications

Server-side Web caching is an important technique used to reduce the User Perceived Latency (UPL). In large-scale multimedia systems, there are many Web proxies, connected with a multimedia server, that can cache some most popular multimedia objects. Multimedia objects have some particular characteristics, e.g., strict QoS requirements. Hence, even some efficient conventional caching strategies based on cache hit ratio, meant for non-multimedia objects, will confront some problems in dealing with the multimedia objects. If we consider additional resources of proxy besides cache space, say bandwidth, we can readily observe that high hit ratio may deteriorate the entire system performance. In this paper, we propose a novel placement model for networked multimedia systems, referred to as H-k/T model, which considers the combined influence of arrival rate, size, and playback time to select the objects to be cached. Based on this model, we propose an innovative Web cache replacement algorithm, named as ART-Greedy algorithm, which can balance the load among the proxies and achieve a minimum Average Response Time (ART) of the requests. Using an event-driven simulation, we evaluate the performance of our proposed algorithm under several situations. Our experimental results conclusively demonstrate that ART-Greedy algorithm outperforms the most popular and commonly used LFU (Least Frequently Used.) algorithm significantly.