Distributed Vod System Based On Proxy Caching Strategy

Internet has grown rapidly in recent years. The developments of both bone network and local access network bring VOD applications a bright future. Since the bandwidth's needs of disk I/O and network are very immense, when facing a large amount of users, server's I/O and network's bandwidth become the bottleneck of the system. The VOD system handles mainly multimedia data, while the multimedia data usually needs much more disk space and bandwidth. In large VOD system, it's not easy to manage efficiently network bandwidth. So it can hardly satisfy the need of the customers.The World Wide Wed system in the Internet has fully confirmed that caching technology is an important way of efficient utilization of bandwidth resources. And so has the VOD system. In particular, only video-prefix caching strategy has been confirmed being efficient and saving storage space, because digital video is huge. proxy is a new technique to reduce client's start delay and network traffic, which gains a good result in the web domain. Because of very large file size and real time restrictions, traditional web proxy techniques are not suitable for streaming media applications. Video proxy techniques have to face more new challenges.This thesis is based on the distributed VOD prototype system researches in video proxy techniques. Main works are as follow:Firstly, a distributed video proxy system has been designed and realized. By adopting cluster techniques, a group of commercial PCs worked as a server to serve the clients. The proxy system has good scalability.Secondly, a segment-based caching replacement policy has been put forward to reduce bandwidth utilization and user perceived delays significantly by adding the middleware component in the video proxy along the path between clients and servers.