基于P2P流媒体的在线直播系统模型研究

在传统网络电视直播系统的基础上,提出了一种基于P2P流媒体的在线直播系统架构,它针对流媒体传输要求带宽高、延迟小、实时性强等特点,采用P2P模型中的混合模型,实现了一种动态自适应的区域自治机制.对P2P网络中的信息源进行实时动态分配,极大地提高了各节点间信息传输速率,并且采用RTP、RTSP等流式传输协议,使整个P2P网络的信息传输稳定性、安全性都有一定的保障.     

局域网下的P2P流媒体直播性能优化方案

随着P2P实时流媒体在网络上的流行,来自P2P实时流媒体应用的流量占据了在ISP主干链路的流量中相当大的比例.对于种类繁多并且私有化了应用层协议的P2P流媒体应用来说,目前很少有针对性的方法在不损害用户播放效果的前提下来缓解其对主干网的流量压力.通过对目前主流的基于Mesh结构的P2P流媒体直播系统工作原理的分析,提出一套基于应用层协议的针对局域网用户的P2P实时流媒体优化方案,能够从整体上有效减少P2P流媒体应用对该局域网外部节点的依赖,同时从下载效率以及播放延时等方面改善该局域网内部的P2P流媒体服务的用户体验.实验结果表明,在局域网内具有一定数量的P2P实时流媒体用户以及相对集中的节目源的情况下,该方案在改善网络流量和用户体验方面均能起到很好的效果.     

P2P流媒体激励机制研究

相对于传统的P2P文件共享系统,P2P流媒体系统的激励机制更为必要.分析并总结了当前P2P流媒体系统中已提出的比较有代表性的几种激励机制:基于信誉的、基于市场的、基于惩罚的、基于社会福利的以及一种自然的激励模型,并讨论了每种机制的典型实例,在此基础上对未来工作进行了展望.     

P2P流媒体服务方案及其关键技术研究

根据近年来P2P流媒体服务方案的研究成果,归纳并总结P2P流媒体的关键技术,包括覆盖网络构建技术、数据调度技术以及各种优化技术。由此可知,P2P流媒体是一种性价比高、扩展性好的流媒体服务体系,并指出P2P流媒体可进一步的研究方向为P2P流媒体的应用与测量、理论分析与建模、体系架构以及与视频编码、移动网络技术的结合等。     

一种基于节点可选度的P2P点播流媒体数据调度算法

当前的P2P(Peer-to-Peer)点播流媒体系统中数据调度算法未能充分利用每个用户节点自身的特性.在分析典型数据调度算法基础上提出一种基于节点可选度的数据调度算法(SSP算法).该算法一方面在调度下载数据块时综合考虑了邻居节点带宽能力及其所拥有的数据信息.另一方面对服务节点的请求处理过程进行了优化.SSP算法有利于提高用户节点播放视频的连续性,降低流媒体服务器的负载压力,从而改善P2P点播流媒体系统的整体服务质量.仿真结果和实际应用表明算法性能良好,适用于用户节点能力差异较大的P2P点播流媒体环境.     

IMS 可管理P2P 流媒体应用服务器的设计与实现

基于IP多媒体子系统的流媒体系统采用的都是传统的客户端/服务器（Client/Server,C/S）架构,当大量用户同时请求流媒体服务时,中心媒体服务器将成为整个系统的性能瓶颈。在参考ETSI TISPAN制定的IMS-based IPTV架构基础上,给出了基于IMS的可管理P2P流媒体系统架构,并根据引入P2P技术的系统需求设计了可管理P2P流媒体应用服务器的软件模块结构及P2P分发树的构建算法。在原有基于C/S架构的流媒体应用服务器基础上,通过扩展集中管理和维护对等节点树P2P模块实现了媒体上传节点的选择,并以直播业务为例进行了原型系统验证。测试结果显示该系统能够有效地将终端节点组织成P2P流媒体分发网络,并有效地降低了媒体服务器的压力,提升了流媒体系统的性能。     

基于Super-peer的P2P流媒体服务系统构架的研究

在分析比对现有P2P流媒体服务系统构架的基础上，提出了一种新的P2P流媒体服务系统构架，在构架中引入了带有冗余的Super—peer结构，使得该流媒体服务系统可以达到较高的效率和健壮性。     

基于P2P平台的流媒体技术

网络改变着我们得生活,越来越多的人都通过网络来观看电视节目,让人们有了更多的频道选择。在此基础上,各种基于P2P流媒体播放软件层出不穷,本文将着重介绍P2P流媒体技术,包括流媒体传输协议以及如何实时传送。最后简要介绍流媒体播放的实现架构。     

基于P2P技术的流媒体直播系统的研究与实现

本文介绍了P2P技术和流媒体的技术框架,并对它们进行研究和分析,并在此基础上设计和实现了一个高质量的流媒体直播系统。     

基于Gossip协议的P2P流媒体直播系统的研究

通过对当今P2P流媒体直播系统主流模型的对比分析,在Gossip协议的基础上,提出一种自适应Gossip协议P2P流媒体直播系统模型,针对节点的异质性实现动态的更新状态和查找节点的机制,充分利用节点的带宽,提高了系统的效率。     

Systematic evaluation of peer‐to‐peer systems using PeerfactSim.KOM

Comparative evaluations of peer‐to‐peer protocols through simulations are a viable approach to judge the performance and costs of the individual protocols in large‐scale networks. In order to support this work, we present the peer‐to‐peer system simulator PeerfactSim.KOM, which we extended over the last years. PeerfactSim.KOM comes with an extensive layer model to support various facets and protocols of peer‐to‐peer networking. In this article, we describe PeerfactSim.KOM and show how it can be used for detailed measurements of large‐scale peer‐to‐peer networks. We enhanced PeerfactSim.KOM with a fine‐grained analyzer concept, with exhaustive automated measurements and gnuplot generators as well as a coordination control to evaluate sets of experiment setups in parallel. Thus, by configuring all experiments and protocols only once and starting the simulator, all desired measurements are performed, analyzed, evaluated, and combined, resulting in a holistic environment for the comparative evaluation of peer‐to‐peer systems. An immediate comparison of different configurations and overlays under different aspects is possible directly after the execution without any manual post‐processing. Copyright © 2015 John Wiley & Sons, Ltd.     

非结构化P2P系统Overlay优化技术综述

非结构化P2P Overlay网络的结构松散, 网络中资源的分布没有明确的限制, 这使得非结构化P2P Overlay网络中的资源搜索在很大程度上依赖于通信开销巨大的泛洪法, 因而非结构化P2P系统在伸缩性, 可用性等方面, 存在明显的不足. 非结构化P2POverlay网络的上述特点决定了非结构化P2P Overlay优化技术的重要性. 本文分四大类别, 对非结构化P2P Overlay优化技术进行了介绍, 分析比较了各类方法的优劣以及它们的适用场合, 并在此基础上对未来工作进行了展望.     

A generic decentralized trust management framework

This paper describes TRUSTPACK , a decentralized trust management framework that provides trust management as a generic service. TRUSTPACK is unique in that it does not provide a central service. Instead, it is run by many autonomous services. This design enables TRUSTPACK to alleviate privacy concerns, as well as potentially provide better personalization and scalability when compared with current centralized solutions. A major component of TRUSTPACK is a generic decentralized graph query processing framework called GRAPHPACK , which was also developed as part of this work. GRAPHPACK consists of a decentralized graph processing language as well as an execution engine, as elaborated in this paper. The paper also presents several examples and a case study showing how TRUSTPACK can be used to handle various trust management scenarios, as well as its incorporation in an existing third party P2P file sharing application. Prototypes of TRUSTPACK and GRAPHPACK are available as open source projects at http://code.google.com/p/trustpack/ and http://code.google.com/p/graphpack/ , respectively. Copyright © 2013 John Wiley & Sons, Ltd.     

P2P-FISM: Mining (recently) frequent item sets from distributed data streams over P2P network

Data intensive large-scale distributed systems like peer-to-peer (P2P) networks are finding large number of applications for social networking, file sharing networks, etc. Global data mining in such P2P environments may be very costly due to the high scale and the asynchronous nature of the P2P networks. The cost further increases in the distributed data stream scenario where peers receive continuous sequence of transactions rapidly. In this paper, we develop an efficient local algorithm, P2P-FISM, for discovering of the network-wide recent frequent itemsets. The algorithm works in a completely asynchronous manner, imposes low communication overhead, a necessity for scalability, transparently tolerates network topology changes, and quickly adapts to changes in the data stream. The paper demonstrates experimental results to corroborate the theoretical claims.     

基于DHT的P2P系统的负载均衡算法

在基于DHT的结构化P2P系统中，DHT的使用以及节点处理能力的不同导致系统中节点的负载不均衡．现有的负载均衡算法存在两个不足：①负载的转移没有考虑节点之间的链路延迟；②算法依赖于系统中固定位置的某些节点．提出了分布式负载均衡算法：每个节点周期性的收集系统局部负载信息，然后选择链路延迟较小的节点进行负载转移．算法依赖于系统中的所有节点，解决了单点失败问题．同时，负载的转移是在链路延迟较小的节点之间进行的．仿真实验表明，①对于各种系统利用率，该算法都可以获得理想的负载均衡效果；②算法可以使负载转移开销减少45％以上．     

The importance of considering unauthentic transactions in trust management systems

In peer-to-peer (P2P) networks, trust management is a key tool to minimize the impact of malicious nodes. EigenTrust is claimed to be one of the most powerful distributed reputation management systems focused on P2P file-sharing applications. It is the theoretical base of other systems, and it has also been directly modified in an attempt to improve its performance. However, none of them give appropriate importance to all the information about transactions. This paper proposes an enhancement of EigenTrust, which considers unsatisfactory transactions in greater depth. Pos&Neg EigenTrust is able to obtain a blacklist of the identities of the malicious nodes. Therefore, it is able to significantly reduce the number of unsatisfactory transactions in the network.     

Workflow-based semantics for peer-to-peer specifications

In this paper we introduce SMoL, a simplified BPEL-like language for specifying peer and service behaviour in P2P systems. We then define a transformational semantics of SMoL in terms of Yet Another Workflow Language (YAWL) workflows, which enables the simulation (e.g., testing possible execution scenarios) and analysis (e.g., verifying reachability or lock freedom) of the behaviour of P2P peers and services.     

一种基于物理网络拓扑的高效Chord模型

在结构化P2P系统中,建立逻辑overlay时没有考虑底层物理网络拓扑结构,其路由机制主要是根据节点逻辑上的相邻性进行设计,导致物理网络邻近节点的延迟较大。该文在Chord 基础上提出一种P-Chord系统模型,利用物理网络的拓扑结构,在节点路由表中增加了邻居表,实验证明P-Chord在路由延迟和覆盖网络的跳数上相比Chord都有较好的改善。     

P2P系统中一种基于声誉的混合抗污染机制

提出一种新的基于节点声誉和目标声誉的混合抗污染机制。该机制由投票节点的声誉决定选定的目标文件的声誉。节点声誉通过引入严厉的惩罚策略及投票激励机制,有效孤立了污染者,刺激了用户对文件污染的警觉度,阻止污染的进一步扩散。仿真结果表明,与目标声誉系统相比,该机制收敛更快,抗污染性能更好。     

Start making sense: The Chatty Web approach for global semantic agreements

This paper describes a novel approach for obtaining semantic interoperability in a bottom–up, semi-automatic manner without relying on pre-existing, global semantic models. We assume that large amounts of data exist that have been organized and annotated according to local schemas. Seeing semantics as a form of agreement, our approach enables the participating data sources to incrementally develop global agreements in an evolutionary and completely decentralized process that solely relies on pair-wise, local interactions.