Web Access Design And Implementation Of The Features Of The Simulator

Web object caching is one of the most prevalent approaches to improving Web performance . Caching can be applied at several locations: at the client, at the proxy server, at the server. Researches show that the hit ratio of web caching can attain 30%-50%. Web caching can improve web performance greatly , but it also put forward many problem.The most important problem in the application of web caching is how to manage web cache efficiently,studying the web access characteristics is the foundation of managing web cache efficiently. Some common characteristics identified in proxy workloads are: (l)the document popularity often follows Zipf's law; (2) the file size distribution for Web documents is heavy-tailed; (3)many(e.g.,50-70%) of the documents are referenced only once; and (4) temporal locality and spacial locality exist in the Web proxy reference stream.Web LOG generation simulator plays an important role in studying web caching system, so far there are two approaches to synthesizing web access workloads: The trace-based approach and The mathematical analytical approach. The trace-based approach uses a history trace and either samples it or permutes the orderings of the requests to generate a new workload; The mathematical analytical approach creates mathematical models to generate workloads. After analyses the web object access characteristics, this paper use mathematical analytical approach to design and implement a web LOG simulator: WEBSIM, in which the web object popularity distribution, web object size distribution and web temporal locality are simulated. WEBSIM not only can synthesize web object access workload, but also has higher flexibility, and provide basis for further studying web caching and prefetching.