This thesis describes the design and implementation of new admission control policies, including the Least Recently Used-Adaptive Threshold (LRU-AT) for Web caching. This policy considers the size of the requested document as an admission constraint in conjunction with the traditional LRU replacement policy. By adaptively tuning the document size, we show that the LRU-AT policy obtains a balance between the document hit ratio and the byte hit ratio. At lower cache sizes, the LRU-AT policy achieves significant improvement in the document hit ratio compared to the traditional LRU and the LRU-Threshold policies. We also show that the LRU-AT policy achieves a higher byte hit ratio when compared to the LRU-T policy. Compared to the LRU policy, we find that the LRU-AT policy has a wide variation in the byte hit ratio, which is probably due to the adaptive tuning of the size filter. At higher cache sizes, the hit ratio with the LRU-AT policy is comparable to the LRU and the LRU-T policies. As opposed to this the byte hit ratio with the LRU-AT policy is significantly higher than that yielded by the LRU-T policy and comparable to the LRU policy. |