对等网P2P技术浅析

对等网(P2P)主要指计算机之间以对等方式形成的网络连接,弱化或完全取消了服务器的作用。对P2P网络的基本概念、技术实现、主要应用进行了介绍,并分析P2P技术与C/S模式互联网的区别。     

基于P2P的远程数据分发技术的应用

对等网络(P2P)有3种主要的组织结构:分布式哈希表(DHT)结构、树形结构、网状结构。P2P技术已经延伸到几乎所有的网络应用领域。该文以远程数据分发技术为例,从减少数据存储与传输成本、节约社会资源的角度出发,结合目前P2P技术的发展趋势,探讨并展望基于P2P技术的远程数据分发模式。     

Chord-PKI: A distributed trust infrastructure based on P2P networks

Many P2P applications require security services such as privacy, anonymity, authentication, and non-repudiation. Such services could be provided through a hierarchical Public Key Infrastructure. However, P2P networks are usually Internet-scale distributed systems comprised of nodes with an undetermined trust level, thus making hierarchical solutions unrealistic. In this paper, we propose Chord-PKI, a distributed PKI architecture which is build upon the Chord overlay network, in order to provide security services for P2P applications. Our solution distributes the functionality of a PKI across the peers by using threshold cryptography and proactive updating. We analyze the security of the proposed infrastructure and through simulations we evaluate its performance for various scenarios of untrusted node distributions.     

基于P2P的资源搜索方法研究

基于Peer-tO-Peer(P2P)理念的搜索方法较传统搜索方法具备更强的实时性和有效性，为新一代搜索引擎的研究提供了新的思路。文中首先介绍了基于F2P搜索方法的特点及分类，描述了各类基于F2P的资源搜索方法。在此基础上，分析了各类搜索方法的优缺点，并阐述了各类搜索方法的改进思路。最后探讨了基于F2P的资源搜索方法的研究与发展方向。     

基于多任务下载的P2P-VoD系统的测量与分析

近些年,P2P点播系统(P2P-Vo D)受到广泛关注,其大多研究工作基于理论性的传统假设,这些假设在真实的系统中是如何表现的不得而知。因此,在真实P2P-Vo D系统中对传统假设进行全面的测量和验证就显得十分迫切。对实际运行的P2P-Vo D系统Cool Fish进行了大量的测量与分析,发现了一些不同于以往假设的结果:节点加入不是简单地服从泊松分布;观看时间和影片流行度不呈严格的正相关性;跳转频率和影片流行度不呈负相关。最后对这些结果进行了深入的分析和讨论。     

面向IPv6的P2P流量管理机制研究

互联网正朝着IPv6的方向发展,P2P应用将是推动IPv6产业化的重要力量,但P2P业务在推动Internet宽带化的同时也带来了因资源过度占用而引起的网络拥塞问题和安全隐患.介绍了对等网络的基本概念,讨论了IPv6对P2P的支持功能,总结了应用于IPv6环境的P2P流量识别策略,设计了支持P2P流量识别的IPv6流标签和跳到跳选项,提出了面向IPv6的P2P流量管理模型,并分析了模型的功能组成及工作机制.     

结构化P2P系统路由机制的研究

基于分布式哈希表的结构化P2P系统得到了广泛的研究,这些系统的网络拓扑结构一般都以图论中的一些广为研究的图作基础,而且大量借鉴了并行系统的研究成果。介绍了几个常见的结构化P2P系统,对其拓扑结构和路由算法作了分析对比。     

基于组件的P2P分布实时数据交换体系结构

提出并实现了一种基于组件／XML的P2P分布实时数据交换系统PeXChange,系统使用XML实现面向多接口的通用数据交换,通过多事件通道和主动发现失效结点实现系统负载均衡和容错处理,采用基于角色的访问控制机制以加强系统的安全性和可管理性。PeXChange在设计和实现上采用组件的大粒度对象化没计范型,具有较好的可扩展性、安全性和容错性。广域网络环境下系统运行表明,PeXChange能够以对等模式提供高质量实时数据交换和共享,各Peer结点在异种数据模式映射、系统负载均衡与容错处理等方面能够满足企业级应用需求。     

基于结构化对等网络的高效分布式任务调度

提出与描述了一个基于结构化对等网络的高效分布式任务调度策略HDTS(High-Efficient Distributed Task Scheduling)。HDTS建立在结构化对等网络的应用层覆盖网络上,保证了系统的非集中性、可扩展性、自组织性,以及规模大的优点。HDTS把基于Chord风格的对等网络协议和容错及高效的多播调度策略结合起来,允许分布式计算的各种大量的子任务在对等网络的节点上高效的调度、分配、执行。除了支持主-从风格的并行计算外,系统允许具有数据依赖的分布式旅行商算法正确的执行,使系统具有通用性和开放性。测试结果表明:HDTS具有正确性与高效性,可以作为对等网络上计算资源高效共享与聚集的可行方案。     

一种P2P网络信息分类检索模型研究

P2P是在分布式自治系统与异构系统之间直接进行资源、服务和信息共享的系统,分布式P2P模型中存在安全性差、流量大和搜寻时间长等弱点,为了解决这些问题,利用"局部访问"原理,提出了一种能够根据历史访问的统计的分类搜索的分布式P2P模型的搜索方法,改善了分布式P2P模型的信息搜索性能,从而为解决上述问题提供了一种有效的途径.     

一种基于差评散布的P2P网络信任机制

面对各种网络攻击,P2P网络需要有效的信任机制隔离恶意节点,保证节点的成功交易。考虑节点行为特征和差评的重要性,提出基于差评散布的信任机制。服务节点一旦提供的服务被给出差评,对其近期交易的相关节点进行差评的散布,加大差评对服务节点声誉的影响力度。经过二次计算的节点声誉值能真实反映节点近期的声誉水平与交易趋势。实验结果表明,该信任机制能保证正常节点的交易成功率,有效对抗各种攻击行为。     

GrouPeer: Dynamic clustering of P2P databases

Sharing structured data in a P2P network is a challenging problem, especially in the absence of a mediated schema. The standard practice of answering a consecutively rewritten query along the propagation path often results in significant loss of information. On the opposite, the use of mediated schemas requires human interaction and global agreement, both during creation and maintenance. In this paper we present GrouPeer, an adaptive, automated approach to both issues in the context of unstructured P2P database overlays. By allowing peers to individually choose which rewritten version of a query to answer and evaluate the received answers, information-rich sources left hidden otherwise are discovered. Gradually, the overlay is restructured as semantically similar peers are clustered together. Experimental results show that our technique produces very accurate answers and builds clusters that are very close to the optimal ones by contacting a very small number of nodes in the overlay.     

Hybrid information retrieval policies based on cooperative cache in mobile P2P networks

The concept of Peer-to-Peer (P2P) has been introduced into mobile networks, which has led to the emergence of mobile P2P networks, and originated potential applications in many fields. However,mobile P2P networks are subject to the limitations of transmission range, and highly dynamic and unpredictable network topology, giving rise to many new challenges for efficient information retrieval. In this paper, we propose an automatic and economical hybrid information retrieval approach based on cooperative cache. In this method, the region covered by a mobile P2P network is partitioned into subregions, each of which is identified by a unique ID and known to all peers. All the subregions then constitute a mobile Kademlia (MKad) network. The proposed hybrid retrieval approach aims to utilize the floodingbased and Distributed Hash Table (DHT)-based schemes in MKad for indexing and searching according to the designed utility functions. To further facilitate information retrieval, we present an effective cache update method by considering all relevant factors. At the same time, the combination of two different methods for cache update is also introduced. One of them is pull based on time stamp including two different pulls: an on-demand pull and a periodical pull, and the other is a push strategy using update records. Furthermore, we provide detailed mathematical analysis on the cache hit ratio of our approach. Simulation experiments in NS-2 showed that the proposed approach is more accurate and efficient than the existing methods.     

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.     

改进RML路由算法及其在基于MAS的P2P系统框架中的应用

P2P计算模型很可能会成为下一个Internet技术的新亮点,基于这种模型的分布式计算已经成为当前研究的热点。目前大部分的研究项目旨在解决P2P的安全、可靠性及路由等问题。文章提出了一种改进的RML路由算法,并介绍了该算法在基于Multi-AgentSystem的P2P系统框架中的应用。     

面向IPTV的CDN-P2P仿真系统

为了准确评估上海电信IPTV系统引入P2P机制后的效果,实现一个CDN-P2P混合架构的IPTV实时图示可扩展仿真系统RGSS(Real-time Graphical Scalable Simulator)。RGSS采用基于消息的事件驱动引擎,支持大规模节点仿真且具有实时可视化功能。实验表明,RGSS在进行大规模节点仿真时,不仅保证了高准确性,而且有效降低了资源消耗,提高了仿真效率。     

基于P2P技术的GIS数据传输方法的研究

随着WebGIS用户数量的不断增加,传统的基于C/S结构网络传输模型已难以满足其不断增长的海量数据传输的要求.提出了一种新的基于P2P技术的GIS数据传输方法来解决该问题.借助相对成熟的P2P技术,由资源服务器搜索资源,然后建立连接,完成地图数据的传输,可有效地提高数据的传输速率.     

推拉结合的P2P VoD数据分发算法P2

提出了一种用于P2P VoD系统的推拉结合的数据分发算法P2.节点采用Pull的方式向合作节点请求数据,同时,在有空闲的上行带宽资源时,用Push的方式向子节点推送数据.间进行实验证明,结合随机选取策略的P2更好的利用节点的上行带宽资源,降低服务器的负载,从而提高整个系统的服务能力.