【摘要】 随着计算机技术和网络技术的不断进步,视频点播服务已经逐渐变成现实,基于协作缓存的视频点播系统是一个分布式结构,中心集群存放影片数据,本地集群缓存数据并提供视频点播服务,具有很好的可扩展性。该文针对VOD系统的协作缓存,提出了静态调度和动态迁移相结合的调度策略,静态调度能够根据影片数据的缓存分布情况,实时调度服务请求,并同时考虑多个VOD服务器的负载动态平衡;动态任务迁移能对服务流分布进行实时分析,并根据服务数据本地化的原则进行服务迁移,进一步提高了协作缓存的命中率。该文阐述了基于协作缓存的视频点播系统的拓扑结构,对静态调度和动态迁移进行了详细设计,并给出了相应的形式化表示。更多还原

【Abstract】 Wit h the advance of computer and network technologies,VOD has begun to become rea listic.A VOD system based on cooperative cache has a distributed topological ar chitecture.In such a system,a central group,which consists of a number of VOD servers,is used to store all video data,and a number of local groups,which a re also composed of several VOD servers,are used to provide VOD service for the clients in their corresponding areas.Obviously,such a system has good flexibi lity.In order to promote the performance of such a VOD system,this paper puts forward a static schedule method with a dynamic migration method.Combining the information about the placing of every movie data with the information of serve rs’ load,the static schedule method can give good performance.By analyzing th e placing of VOD service streams and migrating some streams from a server to a better server,the dynamic migration method can make data access local,so tha t the hit rate of the cooperative cache can be improved.The article expatiates the topological architecture of a VOD system based on cooperative cache,designs the static schedule and dynamic migration method in detail,and formalizes the design.更多还原