A Taste of Crispy Squid

Distributed proxy caches are in use throughout the world to reduce access latency and bandwidth demands for Internet object transfer. The CRISP project seeks to build more eeective distributed Web caches by exploring alternatives to the hierarchical structure and multicast handling of probes common to the most popular distributed Web cache systems. CRISP caches are structured as a collective of autonomous Web proxy servers sharing their cache directories through a common mapping service that can be queried with at most one message exchange. Individual servers may be conngured to replicate all or part of the global map in order to balance access cost, overhead and hit ratio, depending on the size and geographic dispersion of the collective cache. We have prototyped several CRISP cache structures in Crispy Squid, an extension to the Squid Internet Object Cache. We are evaluating these cache structures using Proxycizer, a full-featured package for replaying traces of observed request traac into Web cache prototypes.