The AI3 CacheBone project

Hierarchical WWW cache formation which provides both higher hit rates and saves overall bandwidth consumption through fetching WWW objects and periodically redistributing them among member caches is proposed as an application on a satellite Internet infrastructure. With regular prefetching and distribution of WWW objects, our system can utilize the satellite Internet with continuous streaming data transmissions for efficient WWW caching. Our system consists of a single hub cache and several rim caches. The hub cache is a core unit which is located at the satellite hub station and gathers WWW objects from the Internet, while the rim cache fetches requested WWW objects from the hub cache as well as receiving WWW objects pushed from the hub cache. The prefetching strategy of the rim cache is based on the statistical pattern analysis of user accesses. Traffic monitoring is used to manage both prefetching and object push operations. In order to reduce the consumption of bandwidth in the satellite Internet, multicast transmission of WWW objects is introduced. Furthermore, cached objects are checked regularly with an ''if update' tag so that their consistency can be maintained with reasonable overhead. We discuss our design and implementation of the AI3 CacheBone with our adaptive hierarchical WWW cache formation scheme. Through experiments, we show that the performance of our rim cache shows an improvement of approximately three fold when compared with ordinary hierarchical cache systems such as Squid.