The Application Of Resource Discovery Of P2P Mechanism In Video Grid

The Video Grid, which is based on the technology of Content Distribution Network, integrates current technologies of various multimedia, and encapsulates them into services. This system provides an uniform interface of Video on Demand to users. Due to the video grid adopts the client/server mode,which is based on the CDN architecture, to provide the video service, the video resource discovery of Video Grid is a basically centralized. It limits the expansibility of video grid and leads to the problem of single point of failure. Compared with grid, the resource discovery mechanism of the vod system which is based on the P2P technology possesses the characteristics of the self-organization, the distribution and the dynamic, and can better adapt temselves to the dynamic and the scalability of distributed network.In this paper, based on the research about grid and P2P technologies, we have designed a PGVOD (P2P-Grid Video On Demand) system which can support large-scale users accept the video services at the same time, and has classified the grid resources into two layers. The management and discovery of the upper layer resource adopt centralized mechanism and the lower layer adopt P2P mechanism. Combined with the related concepts and the research experience of the grid and P2P, a combined resource discovery method called PC method is proposed and the process of resource discovery is realized by adopting the related algorithm. The experimentations simulated large concurrent users and designed the density of video on demand, which is according with the Poisson distribution, to test the method proposed. The paper evaluated the model design and algorithm performance.The paper makes following contributions:First, this thesis analyses the structure of current Video Grid and the characteristics of video resources, discusses the function requirement of resource discovery mechanism in grid environment and some disfigurements of resource discovery in current Video Grid.Second, in the system design of the structure of information service, we expand the Monitoring and Discovery Service-MDS and the Index service of Globus technology, and establish a Video Grid system of two-layer structure-PGVOD.Next, according to the inapplicability in multi-attributes and range query, a method of grid resource discovery based on Chord-PC method is proposed. This method enhances the efficiency of resource discovery by restricting the queries and updating of resources to corresponded Virtual Organizations.Finally, this paper simulates the resource discovery in PGVOD by applying the PC method into the arithmetic of resource discovery of the Grid simulator, compares the PC method with other video resource discovery methods. The result shows that, comparing with the resource discovery methods in current Video Grid and VOD systems of P2P manner, PC method has less spending of time and network, lightens the load of servers, and avoids the performance bottleneck.