Design And Implementation Of Http Cache System

In recent years, the number of Internet users and the demand for Internet applications has quickly increased, and a great amount of data traffic consumes network bandwidth, resulting in a decline in network congestion and data transmission speed. Therefore, Web cache technology has become a hot research field of network application. In the thesis, with the current mainstream of cache technology classified and analysed, we find that when the famous cache proxy server, like Squid or Apache, is running and the cache misses the user’s request, the process based on monitoring by interception will add extra user’s access delay.In order to solve this problem, the thesis puts forward the cache technology based on monitoring by bypass mirrored. The technology uses bypass port mirrored to monitor users Internet traffic. According to the tendency of users’request, the system downloads and caches the Web resources which are frequently requested. When the cache system listens to a user’s request and the requested Web resource has been cached, the system will use the HTTP session hijacking technology to guide the user to cache system to obtain the resources needed, so the user no longer needs to connect with a remote Web server. Therefore, the cache technology based on monitoring by bypass mirrored not only reduces network outlet flow, saves bandwidth charges, accelerates user’s access and transmission speed, at the same time solves the issue that cache technology based on monitoring by interception affects the user access delay.Our HTTP cache system based on monitoring by bypass mirrored is designed on the Windows platform.For achieving mirrored monitoring function, The system uses WinPcap tool to capture raw network packets from the image flow, and through network protocol analysis and filtering, the system gets the information of user requesting Web resource. For Web resources which users frequently request, system uses Socket program to download them from external network and cache them on disk. For achieving the management and distribution of disk cache, The system uses IIS program to establish the Intranet HTTP server. Guiding users to obtain the cached resources is by packetaging the response packet containing the cache location, and the system act as Web server to cheat users to obtain resources from Intranet HTTP server.The system uses Microsoft SQL server to show the information of Intranet user requesting Web resource.At the same time, in order to improve the efficiency of the system for the disk cache, the thesis implements hash table structure to store and organize the information users request, then uses hash algorithm to shorten the system processing time delay. And the system also uses cache replacement and resources expired detection methods to improve the cache hit rate and system resources consistency.Finally in the thesis, the HTTP cache system functionality and performance test results show that the designed system can mirroring monitor users’access to Internet traffic data, and hijacking redirect users request. Intranet cache accelerates to reduce user access delay. SQL server database shows the users’resource request status. Thus the HTTP cache system based on monitoring by bypass mirrored is practicable and feasible.