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This work describes a novel live video streaming system for P2P networks, referred to as P2broadcast. The video streaming service has bandwidth requirements to guarantee presentation quality. Therefore, a scalable strategy to quickly find a path from a media server to a client with abundant bandwidth is very important. A common approach in the literature is the bandwidth first (BF) scheme, which allows a newcomer to adopt a BF tree traversal scheme to find its parent peer on the P2P overlay tree to retrieve the media content. The BF scheme is likely to build a deep overlay tree, resulting in long start‐up latency as the number of peers on the overlay tree grows. P2broadcast reduces start‐up latency by organizing peers into hierarchical clusters and making the overlay tree become a ‘short‐and‐wide’ tree. The hierarchical clustering structure enables a newcomer to find its parent peer among the set of peers that are more likely to provide large available bandwidth only. Limiting the set of potential parent peers not only reduces start‐up latency but also improves the system availability. Additionally, unlike the BF scheme that only concerns available bandwidth, P2broadcast utilizes a cost function to evaluate the appropriateness of a potential parent peer. The cost function considers the depth of the newcomer on the overlay tree, making the overlay tree become a short‐and‐wide tree. In addition to start‐up latency reduction, the short‐and‐wide tree feature also alleviates the service interruption probability due to the leaving or failure of a peer. Our simulation results show that P2broadcast greatly outperforms the BF scheme in terms of system availability, and achieves around 66% savings in start‐up latency and 10% decrement in service interruption probability. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
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Chi‐Jen Wu De‐Kai Liu Ren‐Hung Hwang 《International Journal of Communication Systems》2007,20(1):83-102
This work describes a novel location‐aware, self‐organizing, fault‐tolerant peer‐to‐peer (P2P) overlay network, referred to as Laptop. Network locality‐aware considerations are a very important metric for designing a P2P overlay network. Several network proximity schemes have been proposed to enhance the routing efficiency of existing DHT‐based overlay networks. However, these schemes have some drawbacks such as high overlay network and routing table maintenance overhead, or not being completely self‐organizing. As a result, they may result in poor scalability as the number of nodes in the system grows. Laptop constructs a location‐aware overlay network without pre‐determined landmarks and adopts a routing cache scheme to avoid maintaining the routing table periodically. In addition, Laptop significantly reduces the overlay maintenance overhead by making each node maintain only the connectivity between parent and itself. Mathematical analysis and simulations are conducted to evaluate the efficiency, scalability, and robustness of Laptop. Our mathematical analysis shows that the routing path length is bounded by logd N, and the joining and leaving overhead is bounded by d logd N, where N is the number of nodes in the system, and d is the maximum degree of each node on the overlay tree. Our simulation results show that the average latency stretch is 1.6 and the average routing path length is only about three in 10 000 Laptop nodes, and the maximum degree of a node is bounded by 32. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
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现有的服务组合方法多是获取候选服务节点的信息,在集中式组合引擎上搜索路径.这种集中式方法不仅具有单点失效、可扩展性差等缺点,而且候选服务的QoS没有保证,服务搜索空间过大,组合效率较低.文章提出了一种分布式的服务组合方法(BDDSC),将分散在网络中性能有保证的服务节点构建成服务覆盖网络,使各个节点协作执行进行动态服务... 相似文献
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Xianru Liu Shiguo Wang Hong Ji 《International Journal of Communication Systems》2014,27(12):3956-3970
In peer‐to‐peer (P2P) networks, with the aim to support semantic search and keep scalability at the same time, a novel double‐layer P2P protocol is proposed. Firstly, keywords representing resource characteristics are compressed into bloom filters and structured P2P layer is constructed. Secondly, through analyzing one's bloom filters, each node extracts its interest, which is represented by a characteristic vector V. After obtaining common interest among nodes through comparing their Vs, a small‐world model is constructed, and another unstructured P2P layer is obtained. Consequently, on the basis of the decentralized architecture, a double‐layer semantic search P2P protocol is structured. When objective resource is being located, its similarity to local interest is used to determine whether it should be located in unstructured P2P semantic layer or structured layer adaptively, which not only improves search efficiency but also supports semantic location more widely. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
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NGN(下一代网络)采用集中控制的统一的承载网提供综合业务,解决了QoS(服务质量)、安全性和可管理问题,但这种集中管理模式部分削弱和丧失了互联网无所不在的性能,不能有效地支持以P2P为代表的互联网新应用和机-机业务.此外,NGN按服务质量和使用量收费的业务模型,不适应目前消费类宽带业务的发展,以宽带接入包月为代表的互联网运营模式强烈冲击传统电信业务模式,动摇了NGN业务模型的基础.NGN需要并行发展具有分布管理能力的下一代互联网,利用互联网作为基层承载网,在其上应用层建立重叠网支持P2P应用和提供分布式管理,面向广大消费者提供固定和移动宽带互联网业务,支持机-机的各种应用,充分发挥互联网无所不在的优势. 相似文献
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The mismatch between the structured peer-to-peer (P2P) overlay network, which is based on Hashing, and the actual physical network, leads to query repeatedly passing through some nodes in the actual route when it is applied in Ad-hoc networks. An approach of getting an appropriate node identifier (ID) bearing its local physical information is proposed, in which the traditional theory of getting node ID through Hashing the node's Internet protocol (IP) address is abandoned, and a topology-aware overlay network suiting Ad-hoc networks is constructed. The simulation results show that the overlay network constructed in the proposed method can avoid the route being iteratively accessed. Meanwhile, it can effectively minimize the latency and improve the load balance. 相似文献
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在CNGIIPv6上建立诚信安全的P2P环境和分布管理系统 总被引：5，自引：2，他引：5
文章指出中国为实施中国下一代互联网(CNGI)计划而大规模布设IPv6骨干网,这为发展P2P应用、建立诚信安全具有分布管理能力的P2P网络环境提供了机会:一方面在CNGI的IPv6网上一开始就可以实行实名制,从而发展建立网络新秩序;另外一方面可以在CNGI上以无缝和持续演进的方式建立智能结点重叠网,以支持P2P应用并提供分布式管理.文章认为CNGI发展的IPv6终端和IPv6用户网(如家庭网、传感器网等)可以通过在现有IPv4有线/无线接入网和城域网中建立IPv6隧道连接到IPv6骨干网P2P平台,以获得足够的通达能力,并在此基础上发展基于P2P的各种新应用. 相似文献
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提出一种适合于路由表大小为O(logN) 的结构化P2P协议的负载均衡方法,该方法采用负载感知的被动式路由表维护算法和路由算法提高轻载结点作为路由中继结点的概率,并通过一种缓存机制来降低承载热点文件的结点的请求负载.实验结果表明,在用户查询服从Zipf分布的环境下,该负载均衡方法可使系统达到较好的负载均衡. 相似文献
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基于Web Services的分布式服务发现系统的研究 总被引：1，自引：0，他引：1
Internet中分布着大量不同类型的计算服务．为了更有效的查找这些服务，设计了一个面向计算的分布武服务发现系统。网络中的计算资源被部署为Web服务，并通过组件之间的互操作性调用服务。改进了UDDI中的服务订阅机制．并给出了服务部署、服务发布、服务定位和授权认证等关键问题的解决方案。利用集群及PC机环境构建系统。并进行了实际测试。 相似文献
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Mingzhe Fang Dandan Wang Zhenqiang Mi Mohammad S. Obaidat 《International Journal of Communication Systems》2018,31(10)
Web service discovery facilitates the implementation of complex and reconfigurable applications in service‐oriented architecture, such as service selection, composition, and provision. This paper presents an approach for semantic and automated Web service discovery. Our approach to semantic Web service discovery consists of ontology‐based service preprocessor, reasoning‐based service filter, and parameter‐based service matcher. An important feature of this approach is that the relationship among concepts in ontology is quantified and considered as an important factor in the matching process, which results in high precision and recall. Additionally, we propose a filtering method based on logical reasoning to preprocess the large amount of Web services. Through the filtering method, Web services which are feasible in logic are selected to be matched with user requests. So there is a great improvement in the run‐time performance of service discovery approach. Experiments show that our approach is feasible and effective to discover the required Web services. 相似文献
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Recently, the peer‐to‐peer (P2P) architecture has become a popular scheme for Internet users to rapidly exchange files. As reported in previous studies, P2P traffic accounts for a significant portion of overall Internet traffic. Many computing resources, for example, network bandwidth and disk space, may be consumed by P2P clients. Accordingly, in this paper, we devise a novel scheme that integrates advantageous features of both the conventional client–server and the P2P architectures to create an offline downloading service. Specifically, the proposed service acts as an agent that downloads required files from the BitTorrent network without consuming local computing resources. In other words, users can stay offline during the download process. Because the proposed scheme aims to provide service to numerous users at the same time, a proper scheduling technique is adopted to achieve better download performance. Moreover, a free‐riding mechanism is seamlessly incorporated with the proposed priority queuing to facilitate more effective bandwidth utilization. Empirical studies show that our scheme is promising in practical applications. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
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This letter presents an enhancement of EigenTrust. Using the beta distribution, local trust values can be more correctly evaluated. Simulation shows that the proposed scheme calculates the local trust more correctly by up to 8%. For personalization, the proposed scheme provides cumulative transitive values from the local trust to the global trust with mathematically guaranteed convergence. 相似文献
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Ming‐Feng Chen Yi‐Bing Lin Herman C.‐H. Rao Quincy Wu 《Wireless Communications and Mobile Computing》2006,6(1):17-34
This paper proposes iMobile, a proxy‐based platform for developing mobile services for various mobile devices and wireless access technologies. iMobile acts as a message gateway that allows mobile devices to relay messages to each other through various protocols on different access networks. It allows mobile devices to access internet services, corporate databases and to control various network devices. iMobile implements three key abstractions: dev‐let, info‐let and app‐let. An info‐let provides abstract view of information space. An app‐let implements service or application logic by processing information from various info‐lets. A dev‐let receives and sends messages through any particular protocols for mobile devices. The let engine supports user and device profiles for personalization and transcoding, and invokes proper app‐lets and info‐lets to answer requests from a dev‐let. The iMobile modular architecture allows developers to write device drivers, information access methods and application logic independently from each other. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
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Kunwar Pal Mahesh Chandra Govil Mushtaq Ahmed 《International Journal of Communication Systems》2018,31(2)
Nowadays, peer‐to‐peer network plays a significant role in data transfer and communication. The past few years have witnessed considerable growth in this area because of its inherent advantages. Peer‐to‐peer live streaming has a significant impact on video transmission over the Internet. Major factors that influence the performance of P2P live streaming are overlay construction and scheduling strategies. Although, a large number of scheduling schemes are developed but none of them is comprehensive enough to provide solutions to live streaming issues. These suffer from substantial delay and low video quality at the receiver side. In this paper, a new start‐up–based selection procedure and slack time–based scheduling scheme is proposed. The start‐up selection procedure defines the start‐up buffer location for new peer, and the scheduling scheme selects both the chunk and peers. The proposed scheduling scheme uses both push and pull priority–based strategies. The simulation results of the proposed approach demonstrates significant improvement in both the network performance and video quality at the receiver side. It is observed that playback delay, startup delay, and end‐to‐end delay in the network are reduced and quality of the video at receiver side is improved as the distortion and frame loss ratio is decreased. 相似文献
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基于结构匹配的Web服务发现方法常常由于XML Schema定义的灵活性,使得一些本来语义相近的Web服务由于描述结构的不同而匹配失败,且计算开销较高。为此提出了一种基于细粒度数据语义的SAWSDL服务匹配方法和一个数据语义分解转换算法。将每一个消息级参数转换为多个细粒度的数据参数,使得基于消息级的SAWSDL服务匹配转化为更细粒度的数据语义匹配。实验结果表明该方法能够提高Web服务的效果,且计算开销较低。 相似文献
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Peer‐to‐peer (P2P) overlay networks were developed initially for file sharing such as Napster and Gnutella; but later, they have become popular for content sharing, media streaming, telephony applications, etc. Underlay‐unawareness in P2P systems can result in suboptimal peer selection for overlay routing and hence poor performance. In this paper, we present a comprehensive survey of the research work carried out to solve the overlay‐underlay mapping problems up till now. The majority of underlay‐aware proposals for peer selection focus on finding the shortest overlay routes by selecting nearest nodes according to proximity information. Another class of approaches is based on passive or active probing for provision of underlay information to P2P applications. Some other optimizations propose use of P2P middleware to extract, process, and refine underlay information and provide it to P2P overlay applications. Another class of approaches strive to use ISPs or third parties to provide underlay information to P2P overlay applications according to their requirements. We have made a state‐of‐the‐art review and comparison for addressing the overlay‐underlay mismatch in terms of their operation, merits, limitations, and future directions. 相似文献
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Peer‐to‐peer networks are overlay networks that are built on top of communication networks that are called underlay networks. In these networks, peers are unaware of the underlying networks, so the peers choose their neighbors without considering the underlay positions, and therefore, the resultant overlay network may have mismatches with its underlying network, causing redundant end‐to‐end delay. Landmark clustering algorithms, such as mOverlay , are used to solve topology mismatch problem. In the mOverlay algorithm, the overlay network is formed by clusters in which each cluster has a landmark peer. One of the drawbacks of mOverlay is that the selected landmark peer for each cluster is fixed during the operation of the network. Because of the dynamic nature of peer‐to‐peer networks, using a non‐adaptive landmark selection algorithm may not be appropriate. In this paper, an adaptive landmark clustering algorithm obtained from the combination of mOverlay and learning automata is proposed. Learning automata are used to adaptively select appropriate landmark peers for the clusters in such a way that the total communication delay will be minimized. Simulation results have shown that the proposed algorithm outperforms the existing algorithms with respect to communication delay and average round‐trip time between peers within clusters. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献