【作者】 吴杰；

【导师】 张世永；

【作者基本信息】 复旦大学 ， 计算机应用技术， 2008， 博士

【摘要】 随着计算机技术的快速发展以及宽带网络的普及,流媒体应用得到了迅速推广,据最新的互联网发展状况统计显示,中国2.1亿网民中约八成是网络音乐和网络影视的用户,流媒体应用已经成为当今互联网的一项主流应用。由于流媒体应用具有带宽要求高、占用时间长、QoS要求严格等特性,研究具有大规模承载能力,高可扩展性及鲁棒性,高性价比,资源集约,安全,及具有良好QoS保障的,可运营可管理的流媒体内容分发技术成为一个全球范围内流媒体应用领域的一个挑战性课题。与传统的中心式服务或基于CDN架构的服务相比,P2P流媒体具有更好的优越性及潜力,但由于P2P本身存在的问题,该领域仍旧是一个有许多待解决的挑战性难题的活跃研究领域。其需要研究的关键技术问题主要包括:Peer节点的动态性管理,Peer节点的异构性,高效率覆盖网的构建,节点的调度算法,内容安全等。本文针对P2P流媒体内容分发与服务这个课题进行了深入细致的研究,其主要工作和创新点包含如下:1、提出了一种P2P环境下的VoD模型—KadStreaming。KadStreaming采用网状覆盖网(mesh-based overlay network),利用改良的分布式哈希技术(DistributedHash Table),实现地域感知(locality awareness),就近服务,有效地改善了系统数据交互的效率和流媒体服务质量。针对数据调度和节点选择,提出QoS激励的全局能力成长优先模型,通过建立节点的能力模型,节点一方面能找到最优节点获取服务,另一方面系统优先吸纳最优节点加入,通过节点间的有效协商,使系统具有良好的可扩展性及QoS保障,实现有效的Peer节点服务能力的聚集,以支撑大规模流媒体VoD系统的需求。2、提出了基于组织行为学的层次网状P2P直播模型—HimP2P。HimP2P通过采用具有分层特点的网状结构来构建覆盖网,在异构环境下支持多对一服务,具有抗抖动性强,延时小的特点,通过引入组织行为学的概念,建立节点能力及贡献模型,根据节点服务能力来动态调整普通节点在P2P架构中的层次,优化整个系统的覆盖网,从而最终实现P2P网络能力最大化和整体延时最小化。3、提出了P2P与CDN混合的可运营可管理的流媒体内容分发模型—PeerCDN。PeerCDN继承了P2P系统与CDN系统的优点,通过系统模型的合理架构,一方面充分利用商用CDN网络前期的巨大软硬件投资,延续系统稳定可控等优点;另一方面,通过P2P技术的合理采用,提高CDN网络中心节点向边缘缓存节点内容分发的效率,同时通过边缘缓存节点的协调,充分发掘终端用户的上行带宽、存储和计算资源,在较少投入的情况下,显著提升系统的并发能力,实现具有良好QoS保障的大规模流媒体业务的支撑。针对P2P流媒体系统易受内容污染攻击的问题,PeerCDN还提出的内容污染免疫算法,特别针对直播环境,充分利用了CDN的已有架构,提出了通过分布式主动检测和中心式强制隔离相结合的方法,来保证用户获取合法可靠的媒体内容,并对恶意攻击节点进行惩罚,有效提升了系统的可运营性。4、针对P2P流媒体内容服务系统目前的小规模,封闭式等不利于内容运营的问题,提出了基于Web service的内容联盟框架,通过松散耦合的方式实现内容的联盟,提出了一种面向内容服务特定领域的UDDI扩展注册和查询平台及基于XML的内容的注册和交换标准,以支持异构内容服务的统一注册和高效查询,打破P2P流媒体内容服务系统的封闭性,使资源共享,产业发展成为可能。P2P流媒体作为一种新型的流媒体内容分发与服务方法,具有良好的产业化应用前景,对服务提供商和用户都具有较强的吸引力。本文的研究工作为推动P2P流媒体的应用发展提供了良好的理论和实践基础。更多还原

【Abstract】 With the dramatic development of computer technology and the wide deployment of broadband network,the streaming media application gains great popularity.The latest data from the internet statistics show that among 210M internet users of China, about 80%users enjoy network audio and network video services.Streaming media application thus becomes the main application nowadays.As streaming media requires high bandwidth,long duration and strict QoS,it poses a great challenge for researchers to develop a large-scale capable,cost-effective,robust,safe,QoS guaranteeing,friendly-to-ISPs streaming content delivery and service system. Compared with the traditional server centric model and CDN model,P2P has more distinct features.As there are many issues of problem,P2P streaming is still an active research area with many challenging problems to be addressed.For example,peer dynamicity management,peer heterogeneity,efficient overlay construction,peer scheduling and content safety.This dissertation focuses on the P2P streaming content delivery and services,the main contributions are as follows:1.A novel P2P VoD scheme-KadStreaming is proposed.KadStreaming uses mesh-based overlay network and innovated DHT to realize locality awareness and nearby service,it efficiently improves the performance of the system.According to the Peer selection,a QoS incentive global capacity growth first model is put forward.By comparing the capacity of peers,the peers negotiate to provide or get services,the high capability is more likely to get high priority and thus enhance the capacity of the whole system.2.A social behavior based hierarchy-mesh P2P live streaming scheme(HimP2P) is put forward.HimP2P uses hierarchy-mesh overlay network,it supports many to one service model and then has less delay and more robustness.Him will optimize the overlay network by promoting the high capacity peer node,and then benefit the whole system.3.A novel scheme of hybrid P2P streaming system—PeerCDN is proposed. PeerCDN inherits the both excellent features of P2P and CDN system.It makes full use the CDN large amount of hardware/software investment,by using P2P technology,the effect of content delivery among the original server and cache servers was greatly improved.At the same time,by the coordination of cache server,the client Peers’ resource is aggregated.To prevent the system from content pollution attack,an immunity algorithm is proposed.By using the distributed active check and centic polited isolation,the peers are protected from content pollution.4.A web-service based loosely-coupled content alliance framework is presented. The framework integrates the small-scale,isolated content providers together.It suggests an extended-UDDI registration and search platform,and a XML-based information exchange standard.It makes easy to share content with each other and will be conducive to content industry.As a novel approach of streaming media content delivery and service,P2P streaming enjoys good commercial value because it attracts both the service provider and the end-users.This dissertation’s research provides a sound theory and practicial foundation and helps the development of P2P streaming.更多还原