Concurrent Evaluation of Web Cache Replacement and Coherence Strategies

When studying Web cache replacement strategies, it is often assumed that documents are static. Such an assumption may not be realistic, especially when large-size caches are considered. Because of the strong correlation between the efficiency of the cache replacement strategy and the real state of the cached documents, one may expect dramatic changes of the cache performance when there is a possibility of hits on out-of-date documents. The authors’ aim in this study is to outline using simulation the impact of some cache coherence techniques such as the invalidation protocol, the TTL-based strategies, and prefetching on the efficiency of the cache replacement strategies. Using a simple cache model, they will show that the cache hits recorded when using some replacement strategies are more likely to be performed on out-of-date documents. They will show also the impact of the workload used on the outcome of the simulation.