Prefix Caching of Continuous Media Streams in the Internet

互联网普及程度的急剧增长，加上用户访问速度的提高，导致IP网络中对流媒体服务的需求增加。然而，互联网的异构性和分散性，以及缺乏端到端服务质量保证机制，极大地阻碍了向所有客户提供高质量交付和低延迟的努力。多媒体流应用程序的成功取决于开发新技术，以提供低启动延迟和高音频/视频质量，而不需要控制从多媒体源/服务器到最终用户的整个路径。我们提出了一种基于主动代理服务和前缀缓存的方法，它有可能满足这些需求。代理前缀缓存是一种机制，通过这种机制，连续媒体（CM）对象的前几秒钟存储在靠近客户机的代理服务器上。前缀缓存允许代理隐藏长端到端延迟带来的延迟，需要屏蔽不可靠的网络服务，需要处理从源到达的流，或者需要处理代理和客户端之间稀缺的资源。在本提案中，研究人员概述了调查该机制的几个方面的研究，包括：-前缀缓存机制的设计和评估，-前缀缓存与带宽平滑的集成，-在代理上开发有效的资源分配方案，视频源和互联网流量的特征，以供这些调查使用。at&t Research和马萨诸塞大学（University of Massachusetts）的联合参与提供了一种独特的协同效应，这在其他情况下是不可能的。at&t以worldnet流量数据的形式提供对资源的访问，这些数据提供了互联网上当前CM工作负载的快照，并提供了在学术界不容易获得的视频测试平台/原型平台的访问。另一方面，马萨诸塞大学提供了比工业实验室更长远的视角，以及在主动服务、带宽平滑和可靠传输协议领域的专业知识。

The dramatic growth in the popularity of the Internet, coupled with the increase in user accessspeeds, has led to an increased demand for streaming media services in IP networks. However, theheterogeneous and decentralized nature of the Internet, and the lack of end-to-end mechanisms forquality-of-service guarantees, significantly hampers the effort to provide quality delivery and lowdelay to all clients. The success of multimedia streaming applications hinges on developing newtechniques for providing both low start-up delay and high audio/video quality, without requiringcontrol over the entire path from the multimedia source/server to the end users. We propose anapproach based on active proxy services and prefix caching that has the potential of satisfying theserequirements. Proxy prefix caching is a mechanism whereby the first several seconds of a continuousmedia (CM) object are stored at a proxy server close to a client. The prefix cache allows the proxyto hide latencies introduced by either long end-to-end delays, the need to mask unreliable networkservices, the need to process the stream arriving from the source, or the need to deal with scarceresources between the proxy and clients. In this proposal the researchers outline research investigating several aspects of this mechanism which in-clude:-Design and evaluation of preix caching mechanisms,-Integration of prefix caching with bandwidth smoothing,-Development of effective resource allocation schemes at the proxy, and-Characterization of video sources and Internet traffic to feed into the these investigations. The joint participation of AT&T Research and the University of Massachusetts provides a uniquesynergy that would not otherwise be possible. AT&T provides access to resources in the form ofWorldNet traffic data, which supplies a snapshot of current CM workloads in the Internet, andaccess to video testbed/prototyping platforms that are not readily available in academia. On theother hand, UMass provides a much more long-term perspective than is possible at an industriallab, as well as expertise in the area of active services, bandwidth smoothing, and reliable transportprotocols.