Caching protocol method and system based on request frequency and relative storage duration

The invention relates generally to retaining objects in cache and, more particularly, to methods and systems for implementing a protocol for replacing cached objects with recently received objects. A method and system for caching objects and replacing cached objects in an object-transfer environment maintain a dynamic indicator (Pr(f)) for each cached object, with the dynamic indicator being responsive to the frequency of requests for the object and being indicative of the time of storing the cached object relative to storing other cached objects. In a preferred embodiment, the size of the object is also a factor in determining the dynamic indicator of the object. In the most preferred embodiment, the cost of obtaining the object is also a factor. A count of the frequency of requests and the use of the relative time of storage counterbalance each other with respect to maintaining a cached object in local cache. That is, a high frequency of requests favors maintaining the object in cache, but a long period of cache favors evicting the object. Thus, cache pollution is less likely to occur.