Modeling Web Proxy Cache Architectures

In this paper we evaluate the performance of design alternatives for Web proxy cache architectures. Our performance study employs deterministic and stochastic Petri nets (DSPN) as stochastic modeling formalism because DSPN provide an illustrative graphical representation. The presented DSPN models address in particular the sensitivity of the performance of proxy cache architectures on the traffic intensity and burstiness of client requests as well as on the cache size and network transfer times. We employ DSPN for a comparative performance study of two Web proxy cache architectures: a shared proxy cache and a partitioned proxy cache for text and image documents. For comparison and validation purpose, we also present performance figures for a simple Web server without a proxy cache. For both cache architectures, the benefits of prefetching are also investigated.