Effective reference probability incorporating the effect of expiration time in Web cache

Web caching has become an important problem when addressing the performance issues in Web applications. The expiration time of the Web data item is us eful a piece of information for performance enhancement in Web caching. In this paper, we introduce the notion of the effective reference probability that incorporates the. effect of expiration time for Web caching. For a for mal approach, we propose the continuous independent reference model extendi ng the existing independent reference model. Based on this model, we define formally the effective reference probability and derive it theoretically. By simply replacing the reference probability in the existing cache replace ment algorithms with the effective reference probability, we can take the e ffect of expiration time into account. The results of performance experimen ts show that the replacement algorithms using the effective reference proba bility always outperform existing ones. In particular, when the cache fract ion is 0.05 and data update is comparatively frequent (i.e., the update fre quency is more than 1/10 of the reference frequency), the performance is en hanced by more than 30% in LRU-2 and 13% in Aggarwal's method. The results show that the effective reference probability significantly enhances the pe rformance of Web caching when the expiration time is given.