The Study Of Cooperative Web Caching Using RCD Expression

Web caching is a technique applied in Internet, with which the frequently accessed web objects are copied in a more easily accessed network node. Web caching can shorten clients' waiting time and improve Internet's performance without bandwidth increase. So it plays an important role in improving the efficiency of accessing Internet.Web caching has three developing steps those are browser caching, proxy caching and cooperative caching. Among them, cooperative caching is the focus of current study. After recounting the theory, status quo and develop trend of web caching, this article puts out the RCD(Reduced Cache Digests) expression of the cached content and studies cooperative web caching using RCD expression. In RCD, the contents cached in proxy are classified into three groups: the recently accessed, the frequently accessed and the rarely accessed. Because the last group contributes nothing to the whole cache system, RCD only express the first two groups. Thus the dimension of the cached content's index is shortened. On the other hand, RCD especially adapts to servicing for client clusters with the same favoritism to web content, because it can store the accessed frequency of web objects. Based on RCD's frequency-storing characteristic, this article discusses the arithmetic of creating, renewing and accessing RCD index. Finally, considering the users'accessing-frequency, cooperative web caching using RCD index, which is distributed in local switches, is discussed.Academic study and simulative experiment show that the problem tnat each proxy shared by all clients and balancing loading between proxies can't be achieved simultaneously is conquered by the cooperative caching plan based on RCD . In this plan, a L7 switch with RCD provides a fast and effective way for local user to access Internet, resulting from its content-awareness ability exerted fully by RCD.