Variable QoS from Shared Web Caches: User-Centered Design and Value-Sensitive Replacement

Due to differences in server capacity, external bandwidth, and client demand, some Web servers value cache hits more than others. Assuming that a shared cache knows the extent to which different servers value hits, it may employ a value-sensitive replacement policy in order to generate maximum aggregate value for servers. We consider both the prediction and value aspects of this problem and introduce a novel value-sensitive LFU/LRU hybrid which biases the allocation of cache space toward documents whose origin servers value caching most highly. We compare our algorithm with others from the Web caching literature and discuss from an economic standpoint the problems associated with obtaining servers’ private valuation information. Keywords—World Wide Web, caching, quality of service, replacement policies, user-centered design, markets, incentives