Request Scheduling Algorithm Research And Implementation Of Video On Demand System

With the high-speed development of internet technology and unprecedented abundance of network resource, the technology of Video on Demand (VOD) has developed quickly as a stretch of conventional television medium in the inter-connected network. It is statistic that the VOD technology has a very wide foreground; some specialists in the field have even said that the market of it can be measured in billion dollars. Take our country's current instance into consideration, we can see that both software and hardware market of this field are monopolized by foreign companies, and the structure of central service center is still in the highest flight of the system construction field, this structure cannot fulfill the need of handling massive request from large scale areas. Thus, demand of both the market and users calls for the research of new structure and the request schedule on it. So it is very important and useful to research the VOD system structure and the request schedule algorithm on it.In this thesis, we analyze the need of VOD system and its current problem in system structure. Then we bring about a new expansible, distributed cluster structure for the VOD system with fault-tolerance ability to certain extent, the structure can be used in the WAN. On the base of this structure, we worked out a dynamic request schedule algorithm which makes decision on request information and dynamic load of servers and nodes in system. We give a realization of the algorithm and test it under a half-simulative system. Besides, we also compare our algorithm with several classical task schedule algorithms. The result of the test shows that this algorithm has reached the design demand with fault-tolerance ability to some extend. As a supplement of request schedule, we also bring about a media-content schedule algorithm on both node level and server level.