基于特征信息定位的P2P网络模型:Barnet

提出了Barnet,一个基于特征信息定位的Peer-to-Peer网络模型.该模型的目标是为广域网络构建一个高性能、高可用、协同、负载均衡的海量信息资源服务平台.分别描述了Barnet原型系统的构建目标、系统结构、信息资源的组织及信息资源的定位策略.描述了Barnet中所采用的一个基于Peer-to-Peer的分布式命名、定位、查找算法NetShot,讨论了NetShot中节点的命名、节点加入离开、节点间邻接关系和节点间消息传递方式等基本问题.提出了基于特征信息定位技术的概念,并讨论了在Barnet中使用基于特征信息定位技术对具体信息资源进行查找、定位的具体策略.     

A Decentralized Computational Infrastructure for Grid-Based Parallel Asynchronous Iterative Applications

Parallel asynchronous iterative algorithms relax synchronization and communication requirements, and can potentially extend Desktop Grids beyond embarrassingly parallel applications to support a broader class of parallel iterative applications. This paper presents the design and implementation of CometG, a decentralized (peer-to-peer) computational infrastructure that extends Desktop Grid environments to support these applications. CometG provides a decentralized and scalable tuple space, efficient communication and coordination support, and application-level abstractions that can be used to implement Desktop Grid applications based on parallel asynchronous iterative algorithms using the master-worker/BOT paradigm. The deployment and evaluations of CometG and a CometG-based application in a wide-area environment using the PlanetLab [7] test bed, as well as a campus network are presented.     

Sporadic decentralized resource maintenance for P2P distributed storage networks

In this paper, we propose a novel decentralized resource maintenance strategy for peer-to-peer (P2P) distributed storage networks. Our strategy relies on the Wuala overlay network architecture, (The WUALA Project). While the latter is based, for the resource distribution among peers, on the use of erasure codes, e.g., Reed–Solomon codes, here we investigate the system behavior when a simple randomized network coding strategy is applied. We propose to replace the Wuala regular and centralized strategy for resource maintenance with a decentralized strategy, where users regenerate new fragments sporadically, namely every time a resource is retrieved. Both strategies are analyzed, analytically and through simulations, in the presence of either erasure and network coding. It will be shown that the novel sporadic maintenance strategy, when used with randomized network coding, leads to a fully decentralized solution with management complexity much lower than common centralized solutions.     

Supporting Cooperative Software Processes in a Decentralized and Nomadic World

Recent advances in wireless networks enable decentralized cooperative and nomadic work scenarios where mobile users can interact in performing some tasks without being permanently online. Scenarios where connectivity is transient and the network topology may change dynamically are considered. Connectivity among nodes does not require the support offered by a permanent infrastructure but may rely on ad hoc networking facilities. In this paper, a scenario in which a nomadic group of software engineers cooperate in developing an application is investigated. The proposed solution, however, is not software process specific but holds for other cases where shared documents are developed cooperatively by a number of interacting nomadic partners. Support tools for these groups are normally based on a client-server architecture, which appears to be unsuitable in highly dynamic environments. Peer-to-peer solutions, which do not rely on services provided by centralized servers, look more promising. This paper presents a fully decentralized cooperative infrastructure centered around peer-to-peer versioning system (PeerVerSy), a configuration management tool based on a peer-to-peer architecture, which supports cooperative services even when some of the collaborating nodes are offline. Some preliminary experiences gained from its use in a teaching environment are also discussed     

Resource allocation in peer-to-peer networks

Resource allocation in peer-to-peer networks — An excess-based economic model This paper describes economic aspects of GNUnet, a peer-to-peer framework for anonymous distributed file-sharing. GNUnet is decentralized; all nodes are equal peers. In particular, there are no trusted entities in the network. This paper describes an economic model to perform resource allocation and defend against malicious participants in this context. The approach presented does not use credentials or payments; rather, it is based on trust. The design is much like that of a cooperative game in which peers take the role of players. Nodes must cooperate to achieve individual goals. In such a scenario, it is important to be able to distinguish between nodes exhibiting friendly behavior and those exhibiting malicious behavior. GNUnet aims to provide anonymity for its users. Its design makes it hard to link a transaction to the node where it originated from. While anonymity requirements make a global view of the end-points of a transaction infeasible, the local link-to-link messages can be fully authenticated. Our economic model is based entirely on this local view of the network and takes only local decisions.     

Building resilient low-diameter peer-to-peer topologies

As more applications rely on underlying peer-to-peer topologies, the need for efficient and resilient infrastructure has become more pressing. A number of important classes of topologies have emerged over the last several years, all with various strengths and weaknesses. For example, the popular structured peer-to-peer topologies based on distributed hash tables (DHTs) offer applications assured performance, but are not resilient to attacks and major disruptions that are likely in the overlay. In contrast, unstructured topologies where nodes create random connections among themselves on-the-fly, are resilient to attacks but can not offer performance assurances because they often create overlays with large diameters, making some nodes practically unreachable. We propose Phenix, a peer-to-peer algorithm for building resilient low-diameter peer-to-peer topologies that can resist different types of organized and targeted malicious behavior. Phenix leverages the strengths of these existing approaches without inheriting their weaknesses and is capable of building topologies of nodes that follow a power-law while being fully distributed requiring no central server, thus, eliminating the possibility of a single point of failure in the system. We present the design and evaluation of the algorithm and show through extensive analysis, simulation, and experimental results obtained from an implementation on the PlanetLab testbed that Phenix is robust to network dynamics such as bootstrapping mechanisms, joins/leaves, node failure and large-scale network attacks, while maintaining low overhead when implemented in an experimental network.     

A measurement study supporting P2P file-sharing community models

Knowledge of emergent properties of existing peer-to-peer file-sharing communities can be helpful for the design and implementation of innovative peer-to-peer protocols/services that exploit autonomicity, self-configuration, resilience, scalability, and performance. It is well known that the performance of this class of peer-to-peer applications depends on several parameters that represent the topological structure of the overlay network, the users’ behavior, and resource dynamics. Estimation of these parameters is difficult, but it is crucial for analytical models as well as for realistic simulation of peer-to-peer applications.In this paper, we present an active measurement-based study designed to glean insights on the above parameters within the Gnutella network. The measurement software that we developed is able to collect topological information about the overlay network topology in a few minutes; in a second step, it contacts the users discovered during the topological measurement in order to acquire a novel dataset regarding the shared resources.     

基于Agent的Peer-to-Peer式分布式构件库系统

为解决构件库中存在的种种问题,在分析了软件复用现状和构件库的特点的基础上,提出了一种基于Agent的P2P式的分布式构件库系统,阐述了系统的体系结构并在理论基础上开发出了原型系统。该系统能够达到软构件复用的目的,验证了方法的可行性。     

Distribution and synchronisation of engineering information using active database technology

Today, work collaboration is normal practice in developing modern products. Engineering collaborative work involves a number of team members that need to share and exchange design ideas while working with engineering analysis tools such as mechanical computer aided engineering systems. This work presents the M-Sync prototype system that uses an active database approach to enable exchange of engineering information among distributed team members in a timely manner. The distributed data is fully accessible by the local member and is automatically synchronised between different places using a database management system that support event-condition-action (ECA) database rules. Only updates introduced at one location are distributed to other locations, thereby minimizing information transfer and enhancing performance. Members working at different locations can therefore work in a peer-to-peer (P2P) manner and interactively manipulate the same set of information at the same time.     

GoDisco++: A gossip algorithm for information dissemination in multi-dimensional community networks

In this paper we propose GoDisco++, a gossip based approach for information dissemination in online social community networks. GoDiscoo++ uses local information available to nodes—that is information associated with a node and its neighbors. The algorithm exploits multiple relations which may exist between nodes, and applies social principles and behavior inspired decentralized mechanisms for targeted dissemination. The dissemination process works with the dual aims of (i) maximizing the spread among relevant nodes (high recall) and (ii) minimizing spamming among non-relevant nodes (high precision). Such a designed dissemination scheme can have interesting applications like probabilistic publish/subscribe, decentralized recommendation and contextual advertisement systems, to name a few. We validate the proposed approach with simulation experiments performed using real and synthetic datasets.     

PECOLE: P2P multimedia collaborative environment

PECOLE (Peer-to-pEer COLlaborative Environment) is a fully decentralized multimedia collaborative environment that supports a wide range of collaborative multimedia applications, including chat, shared browsing, shared telepointer, multipoint-to-multipoint audio/video conferencing and multilingual collaboration. PECOLE can intelligently run on very constrained resources, is highly resilient, scalable and does not rely on dedicated servers. Instead, PECOLE is built upon a Peer-to-Peer (P2P) overlay network, using SUN’s JXTA framework and SWT technology. In this paper, we present the architecture and implementation of PECOLE with the performance results of the tests we conducted.

P2P应用程序及设计

Napster 和QICQ一样的P2P应用程序已经受到了越来越多网络用户的青睐，P2P应用程序使得用户可以利用现有的网络，以平等的方式共享彼此的资源，极大地提高了方便性。微软的NET框架提供了一个丰富的开发P2P应用的平台。本文介绍了P2P应用程序的有关概念以及如何利用Microsoft NET编写P2P应用程序。     

Storing and Indexing Spatial Data in P2P Systems

The peer-to-peer (P2P) paradigm has become very popular for storing and sharing information in a totally decentralized manner. At first, research focused on P2P systems that host 1D data. Nowadays, the need for P2P applications with multidimensional data has emerged, motivating research on P2P systems that manage such data. The majority of the proposed techniques are based either on the distribution of centralized indexes or on the reduction of multidimensional data to one dimension. Our goal is to create from scratch a technique that is inherently distributed and also maintains the multidimensionality of data. Our focus is on structured P2P systems that share spatial information. We present SpatialP2P, a totally decentralized indexing and searching framework that is suitable for spatial data. SpatialP2P supports P2P applications in which spatial information of various sizes can be dynamically inserted or deleted, and peers can join or leave. The proposed technique preserves well locality and directionality of space.     

Privacy-preserving data infrastructure for smart home appliances based on the Octopus DHT

Smart homes are about to become reality, involving technology such as Radio-Frequency Identification (RFID), which enables querying for extended product information from the manufacturer or from public databases. However, every query for information issued from a smart home could adversely affect the privacy of its inhabitants. Since every Electronic Product Code assigned to RFID-equipped objects is unique, it is easily possible to create detailed and long-term customer profiles by linking queries on particular items to a specific person. In order to address the privacy problem, this paper proposes a novel peer-to-peer (P2P) infrastructure for organized sharing and private querying of data, which is formed by many smart devices across several homes. The efficiency of this approach is examined with experiments involving several hundred nodes. Furthermore, larger peer-to-peer networks of smart home appliances are simulated. According to our evaluation, the proposed solution is able to satisfy real-time requirements in settings where smart devices are geographically close. Moreover, the architecture can be used to store information of nearly one million different products within a network of one thousand nodes, which is a reasonable size for a local collaborative infrastructure between smart homes in towns or cities.     

P2P环境中的skyline查询综述

随着数据规模的增长以及网络技术的发展,对等网络(P2P)作为一种分布式信息共享与搜索的平台引起了越来越广泛的关注。基于对等网络高度动态、高度分散、扩展性强等特点,P2P上的skyline计算方法不仅需要满足集中式skyline计算方法的各种要求,还需要考虑减小网络通讯量、减少平均节点访问数、保持负载平衡等。文中对这个发展领域的最新技术进行了研究,并且描述了分布式skyline方法的目的和主要原理,概括了适用于P2P环境中的现有方法,并进行了性能比较分析。最后,给出了P2P环境skyline计算的未来发展方向。     

Quantitative Assessment of a Peer-to-peer Cooperative Infrastructure Using Stochastic Well-Formed Nets

Traditional support tools for software engineers, normally based on a client-server architecture, are unsuitable to deal with the new issues emerging from the current (and future) cooperative work scenarios (where connectivity is intrinsically transient, the number of interacting partners dynamically changes, etc.). This paper presents a quantitative assessment of a fully decentralized, peer-to-peer, cooperative infrastructure. Stochastic Well-Formed Nets (SWNs) modelling the new peer-to-peer architecture, and a traditional (client-server) one, are developed and analysed: we used SWNs for their ability to directly exploit the symmetries intrinsically present in the modelled systems, thus greatly reducing the complexity of the analysis. The main goal is to compare the impact of the two alternative protocols on the collaborative work. Together with the performance figures of interest, methodological issues concerning the choice of the most appropriate model abstraction level, the adoption of a compositional modelling approach, and the management of the model complexity are also discussed.     

基于主动P2P网络架构的视频点播系统设计

针对当前P2P(peer-to-peer)网络只能通过固定的协议和服务有限地利用节点资源的弱点提出了主动P2P网络(APN)架构。文中结合P2P网络技术和主动网络技术各自的优点,把P2P网络的服务和协议代码封装在数据包中,随数据包一起传送,并由需要的节点加载和执行,从而完成服务和协议的动态扩充和部署。文中基于此架构提出的视频点播系统的设计方案,提高了服务质量。     

TCR: a trustworthy and churn-resilient academic distribution and retrieval system in P2P networks

As the number of people using the internet has surged over the past few years, more and more people are choosing to share and retrieve information online. There are several decentralized retrieval applications that provide file-sharing platforms for exactly this purpose. However, these applications cannot guarantee churn resilience, trustworthiness, or low cost of retrieval. Therefore, in this paper, we present a system called trustworthy and churn-resilient academic distribution and retrieval system in P2P networks, or TCR, which: (1) ensures that information will not be centralized by central network administrators; (2) utilizes LSH to classify nodes with similar research topics into a local subnetwork, and applies routing algorithms with trust score equations to determine the next trustworthy node to forward the message, thus ensuring each node can accurately and efficiently find its trustworthy nodes within only a few hops; (3) provides a trustworthy management system that itself deals in trustworthiness, ensuring that even when there is a large proportion of malicious nodes, the system can still detect and punish misbehaving nodes; (4) guarantees that nodes can still retrieve the desired files even when in high-churn networks. We finally demonstrate that our TCR entails low message costs, provides high match rates, detects malicious nodes, and ensures churn resilience and search efficiency when compared to other P2P retrieval systems.

     

An autonomic approach for P2P/cloud collaborative environments

The rise of Cloud Computing has progressively dimmed the interest in volunteer and peer-to-peer computing, in general. However, efficient and cost-effective large scale distributed collaborative environments cannot be achieved leveraging upon the Cloud alone. In this paper, we propose a novel hybrid P2P/cloud approach where components and protocols are autonomically configured according to specific target goals, such as cost-effectiveness, reliability and availability. The proposed approach is based on the Networked Autonomic Machine (NAM) framework, which allows distributed system designers to include different kinds of cost and performance constraints. As an example, we show how the NAM-based approach can be used to design collaborative storage systems, enabling the definition of an autonomic policy to decide, according to cost minimization and data availability goals, how to part data chunks among peer nodes and Cloud, based on the local perception of the P2P network.     

<Emphasis Type="SmallCaps">MiCa</Emphasis>: Lightweight and mobile collaboration across a collaborative editing service in the cloud

Nowadays, we assist to an explosion of mobile applications due to the rapid development of mobile devices, which are becoming the device of choice for people to collaborate with family members, friends and business colleagues and/or customers. Mobile devices (such as smartphones, tablets and laptops) are well-suited for information delivery than sophisticated desktop PCs in many professional areas (e.g. writing reports for disaster management). However, collaboratively editing a shared document in real-time through ad-hoc peer-to-peer mobile networks requires increasing amounts of computation, data storage and network communication. More particularly, preserving the consistency in a decentralized way of the manipulated shared document under constraints of the mobile applications, namely the freshness and the energy consumption, remains still problematic. In this paper, we propose a new cloud service-based approach, called MiCa (Mobile Collaboration in the Cloud), to achieve efficient and scalable real-time editing works by allowing mobile users an online access to abundant computing power and data storage. Our service is a two levels system. The first level provides self-protocol to create clones of mobiles, manage users’ groups and recover failed clones in the cloud. The second level supports safe mechanisms for synchronizing collaborative works in fully decentralized way. On the mobile side, the energy consumption is largely reduced since all procedures for maintaining consistency of shared documents are executed on the clone side. Based on three important criteria (energy consumption, network traffic and responsiveness time), an experimental evaluation demonstrates the efficiency and effectiveness of our service MiCa.