5,280 research outputs found

    Fine Grained Component Engineering of Adaptive Overlays: Experiences and Perspectives

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    Recent years have seen significant research being carried out into peer-to-peer (P2P) systems. This work has focused on the styles and applications of P2P computing, from grid computation to content distribution; however, little investigation has been performed into how these systems are built. Component based engineering is an approach that has seen successful deployment in the field of middleware development; functionality is encapsulated in ‘building blocks’ that can be dynamically plugged together to form complete systems. This allows efficient, flexible and adaptable systems to be built with lower overhead and development complexity. This paper presents an investigation into the potential of using component based engineering in the design and construction of peer-to-peer overlays. It is highlighted that the quality of these properties is dictated by the component architecture used to implement the system. Three reusable decomposition architectures are designed and evaluated using Chord and Pastry case studies. These demonstrate that significant improvements can be made over traditional design approaches resulting in much more reusable, (re)configurable and extensible systems

    The state of peer-to-peer network simulators

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    Networking research often relies on simulation in order to test and evaluate new ideas. An important requirement of this process is that results must be reproducible so that other researchers can replicate, validate and extend existing work. We look at the landscape of simulators for research in peer-to-peer (P2P) networks by conducting a survey of a combined total of over 280 papers from before and after 2007 (the year of the last survey in this area), and comment on the large quantity of research using bespoke, closed-source simulators. We propose a set of criteria that P2P simulators should meet, and poll the P2P research community for their agreement. We aim to drive the community towards performing their experiments on simulators that allow for others to validate their results

    Handling Network Partitions and Mergers in Structured Overlay Networks

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    Structured overlay networks form a major class of peer-to-peer systems, which are touted for their abilities to scale, tolerate failures, and self-manage. Any long-lived Internet-scale distributed system is destined to face network partitions. Although the problem of network partitions and mergers is highly related to fault-tolerance and self-management in large-scale systems, it has hardly been studied in the context of structured peer-to-peer systems. These systems have mainly been studied under churn (frequent joins/failures), which as a side effect solves the problem of network partitions, as it is similar to massive node failures. Yet, the crucial aspect of network mergers has been ignored. In fact, it has been claimed that ring-based structured overlay networks, which constitute the majority of the structured overlays, are intrinsically ill-suited for merging rings. In this paper, we present an algorithm for merging multiple similar ring-based overlays when the underlying network merges. We examine the solution in dynamic conditions, showing how our solution is resilient to churn during the merger, something widely believed to be difficult or impossible. We evaluate the algorithm for various scenarios and show that even when falsely detecting a merger, the algorithm quickly terminates and does not clutter the network with many messages. The algorithm is flexible as the tradeoff between message complexity and time complexity can be adjusted by a parameter

    Talking to the Empowered Consumer Dealing with the Shift of Power

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    The concept of the empowered consumer cannot be considered as a field of exact scientific research yet. Nevertheless, it has become part of scholars’ interest and gains more and more importance in the research of organisational relationships with customers. It is suggested that two influencing criteria are especially at the forefront: The emergence of the Internet, which effected that barriers to collect and to disseminate information across boundaries were decisively reduced. As a consequence consumers could organise globally and collect and exchange information and experiences about organisations and their products. Furthermore, flexible interactivity between companies and consumers, but particularly from consumers to consumers enable direct interaction changing many previously established rules of doing business. Due to these new opportunities new business models developed and the proposition is that intangible values such as reputation gained even more importance and influence tangible outcomes. Suggestions are that 1.), this concept links communication, corporate behaviour and legitimacy of activities influencing reputation as a driver of value. 2.), reputation as a corporate asset can be managed but it is beyond the pure control of an organisation. 3.), reputation is part of public perception, which an organisation has to build, maintain and expand depending on communicative abilities and willingness to accept consumers as a centre of power. The following discussion will present Grunig et al.’s communication model explaining changed organisational challenges. It is put forward as a framework for marketing for times in which online opportunities added to the earlier b2b and b2c models c2c and P2P considerations and architectures. The annual studies of the market research institute puls undertaking regular representative research among German consumers since November 2005 will present evidence for the relationship of improved prices, which may be achieved, and the perception a firm possesses. This paper deals mostly with German examples and data, but the hypothesis is that a) the general situation in other Western countries is alike, but needs b) specific additional research, since cultural differences are expected to have a considerable influence, especially when criteria such as individualist and collectivist organisation of society and high and low context communication styles are involved. Hence, the results of the same study in different countries are therefore expected to present some variation. Additionally, the Cluetrain Manifesto challenges corporate behaviour of those companies still believing to have the ability to control information disseminated by and written about it. Examples provided will support the hypothesis that powerful consumers may have significant impact on organisational behaviour, decision-making and outcomes. Keywords: Empowered Consumer Concept, Symmetric Two-way communication, Reputation, c2c, P2

    Exploiting the Synergy Between Gossiping and Structured Overlays

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    In this position paper we argue for exploiting the synergy between gossip-based algorithms and structured overlay networks (SON). These two strands of research have both aimed at building fault-tolerant, dynamic, self-managing, and large-scale distributed systems. Despite the common goals, the two areas have, however, been relatively isolated. We focus on three problem domains where there is an untapped potential of using gossiping combined with SONs. We argue for applying gossip-based membership for ring-based SONs---such as Chord and Bamboo---to make them handle partition mergers and loopy networks. We argue that small world SONs---such as Accordion and Mercury---are specifically well-suited for gossip-based membership management. The benefits would be better graph-theoretic properties. Finally, we argue that gossip-based algorithms could use the overlay constructed by SONs. For example, many unreliable broadcast algorithms for SONs could be augmented with anti-entropy protocols. Similarly, gossip-based aggregation could be used in SONs for network size estimation and load-balancing purposes

    A component-based middleware framework for configurable and reconfigurable Grid computing

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    Significant progress has been made in the design and development of Grid middleware which, in its present form, is founded on Web services technologies. However, we argue that present-day Grid middleware is severely limited in supporting projected next-generation applications which will involve pervasive and heterogeneous networked infrastructures, and advanced services such as collaborative distributed visualization. In this paper we discuss a new Grid middleware framework that features (i) support for advanced network services based on the novel concept of pluggable overlay networks, (ii) an architectural framework for constructing bespoke Grid middleware platforms in terms of 'middleware domains' such as extensible interaction types and resource discovery. We believe that such features will become increasingly essential with the emergence of next-generation e-Science applications. Copyright (c) 2005 John Wiley & Sons, Ltd

    Agent-oriented Modeling for Collaborative Learning Environments: A Peer-to-Peer Helpdesk Case Study

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    In this paper, we present the analysis and modelling of Help&Learn, an agent-based peer-to-peer helpdesk system to support extra-class interactions among students and teachers. Help&Learn expands the student’s possibility of solving problems, getting involved in a cooperative learning experience that transcends the limits of classrooms. To model Help&Learn, we have used Agent-Object-Relationship Modeling Language (AORML), an UML extension for agent-oriented information systems modeling. The aim of this research is two-fold. On one hand, we aim at modeling the variety of roles and the complexity of their interactions and activities within the Help&Learn system. On the other hand, we aim at showing the expressive power and the modeling strengths of AORML
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