Research On Proxy Caching Techniques For The Internet

With the development of Internet technologies and Web services, Web traffic still increases exponentially. It results in severe network bandwidth scarcity, network congestion and server overloading, which are the key issues affecting the continuous growing of the Internet. Proxy cache is the main and effective technique to solve these issues. Now it has become an international main research area in which the studies on consistency policies and replacement policies always are the two directions of research, while the front of research on proxy caching techniques is how to better incorporate these two policies which results in a desirable performance of a proxy caching system. In this paper, the research is made more thoroughly on the proxy caching techniques for the Internet. The main results are as follows.1.According to the research on proxy cache consistency policies, it is discussed that Adaptive TTL is more attractive in weak consistency policies, which can be easily implemented and reduce the probability of returning stale data to users.2.According to the research on proxy cache replacement policies, it is discussed that replacement algorithms based on cost/value model arepreferable. However, the model requires to be modified and simplified to easily calculate, to reflect Web access characteristics and to reduce access latency.3. A new performance metric called staleness-hit rate is proposed. It balances these two performance metrics. Therefore, it can better estimate all the algorithms of proxy cache and the overall performance of a proxy caching system.4. A new algorithm called ACR (Adaptive Consistency and Replacement algorithm) is proposed, designed and implemented. It incorporates cache consistency policy with cache replacement policy in which the cache consistency policy is Adaptive TTL mechanism, while the cache replacement policy is based on a cost/value model. It can better incorporate these two policies and reflect Web access characteristics. It also can guarantee returning the fresher data to users with the lower cost, which reflects the superiority of a combination of these two policies and improves the overall performance of a proxy caching system. Using Trace-Driven simulation, the results show that ACR algorithm is better than several traditional algorithms in staleness-hit rate, hence ACR algorithm proves to be rational, effective and practical.