Flexible Open Caching for the Web

Caching plays a vital role in the performance of any large-scale distributed system and, as the variety and number of Web applications grows, is becoming an increasingly important research topic within the Web community. Existing caching mechanisms are largely transparent to their users and cater for resources which are primarily read-only, offering little support for customisable or complex caching strategies. In this paper we examine the deficiencies in these mechanisms with regard to applications with requirements for shared access to data where clients may require a variety of consistency guarantees. We present 'open' caching within an object-oriented framework, an approach to solving these problems which, instead of offering caching transparency makes the caching mechanism highly visible allowing great flexibility in caching choices. Our implementation is built upon the W3Objects infrastructure and allows clients to make caching decisions for individual resources with minimal impact upon other resources which do not support our mechanisms.