Abstract: The efficient delivery of web content has been identified
as a key issue of research for some time. Forward (or
reverse) proxies, which are positioned along the request
route from the users' browsers to the origin content servers,
maintain a cache with copies of content from their origin
servers. The strategic placement of proxies across the
backbone ISP or the Content Delivery Network can
drastically improve the performance of the system (in terms
of network bandwidth savings, origin server load, and
user-request latency).
The ultimate goal of this work is to develop a tool that
decides on the position and the number of proxies required
in order to achieve given performance improvements
(expressed in terms of network bandwidth, origin server
load, and user-latency). We believe such a tool will be very
helpful to ISPs/CDNs, content providers, and end-users
and is, thus, very much lacking.
Abstract: Numerous research efforts have produced a large number of algorithms and mechanisms for web proxy caches. In order to build powerful webproxies and understand their performance, one must be able to appreciate the impact and significance of earlier contributions and how they can be integrated. To do this we employ a cache replacement algorithm, 'CSP', which integrates key knowledge from previous work. CSP utilizes the communication Cost to fetch web objects, the objects' Sizes, their Popularities, an auxiliary cache and a cache admission control algorithm. We study the impact of these components with respect to hit ratio, latency, and bandwidth requirements.
Numerous research efforts have produced a large number of algorithms and mechanisms for web proxy caches. In order to build powerful webproxies and understand their performance, one must be able to appreciate the impact and significance of earlier contributions and how they can be integrated To do this we employ a cache replacement algorithm, 'CSP, which integrates key knowledge from previous work. CSP utilizes the communication Cost to fetch web objects, the objects' Sizes, their Popularifies, an auxiliary cache and a cache admission control algorithm. We study the impact of these components with respect to hit ratio, latency, and bandwidth requirements. Our results show that there are clear performance gains when utilizing the communication cost, the popularity of objects, and the auxiliary cache. In contrast, the size of objects and the admission controller have a negligible performance impact. Our major conclusions going against those in related work are that (i) LRU is preferable to CSP for important parameter values, (ii) accounting for the objects' sizes does not improve latency and/or bandwidth requirements, and (iii) the collaboration of nearby proxies is not very beneficial. Based on these results, we chart the problem solution space, identifying which algorithm is preferable and under which conditions. Finally, we develop a dynamic replacement algorithm that continuously utilizes the best algorithm as the problem-parameter values (e.g., the access distributions) change with time.