15,492 research outputs found
Gossip-based self-managing services for large scale dynamic networks
Modern IP networks are dynamic, large-scale and heterogeneous. This implies that they are more unpredictable and difficult to maintain and build upon. Implementation and management of decentralized applications that exploit these networks can be enabled only through a set of special middleware services that shield the application from the scale, dynamism and heterogeneity of the environment. Among others, these services have to provide communication services (routing, multicasting, etc.) and global information like network size, load distribution, etc. The goal is not to provide abstractions that hide the distributedness of the system, but rather, to hide the unpleasant features of the system, such as dynamism, scale and heterogeneity. Most importantly, these services have to be self-managing: they have to be able to maintain certain properties in the face of extreme dynamism of the network. In this manner, such services can serve as the lowest layer that makes possible building more complex applications, or simply as a plugin to enhance existing systems, for example, GRID environments. Apart from self-management, we require that the services be simple and lightweight, to allow easy implementation and incur low cost. Our approach to achieving these goals is based on the gossip communication model. Gossip protocols are simple, robust and scalable, besides, they can be applied to implement not only information dissemination, but several other functions, as we will show. So far, we have designed gossip-based protocols for maintaining random overlays, which define group membership. Based on this random overlay, we have designed gossip-based protocols to calculate aggregate values such as maxima, average, sum, variance, etc. We have also developed protocols to build several structured overlays in this framework, including superpeer, torus, ring, binary tree, etc. These protocols build on the random overlay and also on aggregate values. The gossip-based model is well suited to dynamic and large networks. Our protocols are extremely simple to implement while being robust and adaptive without adding any extra components or control loops. Our approach also support composition at a local level. At each node in the network, the same services are available: for example, data aggregation uses the random overlay (peer sampling service) and superpeer topology construction applies aggregate values, such as maximal and average capacity. In fact, protocols that implement the different services are heavily interconnected and form a modular system within this lighweight self-managing service layer. While this presentation focuses on the self-managing systems services, it is clear that other application-level services can also be built at higher layers. These services can be proactive, like load balancing, that can make use of the target (average) load and overlays for optimization of load transfer, or reactive, like broadcasting or search, that can be performed on top of an appropriate overlay network (eg spanning tree or superpeer network), maintained by the lighweight self-managing systems services
Exploiting the Synergy Between Gossiping and Structured Overlays
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
Mobile Computing in Digital Ecosystems: Design Issues and Challenges
In this paper we argue that the set of wireless, mobile devices (e.g.,
portable telephones, tablet PCs, GPS navigators, media players) commonly used
by human users enables the construction of what we term a digital ecosystem,
i.e., an ecosystem constructed out of so-called digital organisms (see below),
that can foster the development of novel distributed services. In this context,
a human user equipped with his/her own mobile devices, can be though of as a
digital organism (DO), a subsystem characterized by a set of peculiar features
and resources it can offer to the rest of the ecosystem for use from its peer
DOs. The internal organization of the DO must address issues of management of
its own resources, including power consumption. Inside the DO and among DOs,
peer-to-peer interaction mechanisms can be conveniently deployed to favor
resource sharing and data dissemination. Throughout this paper, we show that
most of the solutions and technologies needed to construct a digital ecosystem
are already available. What is still missing is a framework (i.e., mechanisms,
protocols, services) that can support effectively the integration and
cooperation of these technologies. In addition, in the following we show that
that framework can be implemented as a middleware subsystem that enables novel
and ubiquitous forms of computation and communication. Finally, in order to
illustrate the effectiveness of our approach, we introduce some experimental
results we have obtained from preliminary implementations of (parts of) that
subsystem.Comment: Proceedings of the 7th International wireless Communications and
Mobile Computing conference (IWCMC-2011), Emergency Management: Communication
and Computing Platforms Worksho
Handling Network Partitions and Mergers in Structured Overlay Networks
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
Improving the Scalability of DPWS-Based Networked Infrastructures
The Devices Profile for Web Services (DPWS) specification enables seamless
discovery, configuration, and interoperability of networked devices in various
settings, ranging from home automation and multimedia to manufacturing
equipment and data centers. Unfortunately, the sheer simplicity of event
notification mechanisms that makes it fit for resource-constrained devices,
makes it hard to scale to large infrastructures with more stringent
dependability requirements, ironically, where self-configuration would be most
useful. In this report, we address this challenge with a proposal to integrate
gossip-based dissemination in DPWS, thus maintaining compatibility with
original assumptions of the specification, and avoiding a centralized
configuration server or custom black-box middleware components. In detail, we
show how our approach provides an evolutionary and non-intrusive solution to
the scalability limitations of DPWS and experimentally evaluate it with an
implementation based on the the Web Services for Devices (WS4D) Java Multi
Edition DPWS Stack (JMEDS).Comment: 28 pages, Technical Repor
BaseFs - Basically Acailable, Soft State, Eventually Consistent Filesystem for Cluster Management
A peer-to-peer distributed filesystem for community cloud management. https://github.com/glic3rinu/basef
From supply chains to demand networks. Agents in retailing: the electrical bazaar
A paradigm shift is taking place in logistics. The focus is changing from operational effectiveness to adaptation. Supply Chains will develop into networks that will adapt to consumer demand in almost real time. Time to market, capacity of adaptation and enrichment of customer experience seem to be the key elements of this new paradigm. In this environment emerging technologies like RFID (Radio Frequency ID), Intelligent Products and the Internet, are triggering a reconsideration of methods, procedures and goals. We present a Multiagent System framework specialized in retail that addresses these changes with the use of rational agents and takes advantages of the new market opportunities. Like in an old bazaar, agents able to learn, cooperate, take advantage of gossip and distinguish between collaborators and competitors, have the ability to adapt, learn and react to a changing environment better than any other structure. Keywords: Supply Chains, Distributed Artificial Intelligence, Multiagent System.Postprint (published version
04411 Abtracts Collection -- Service Management and Self-Organization in IP-based Networks
From 03.10.04 to 06.10.04,
the Dagstuhl Seminar
04411 ``Service Management and Self-Organization in IP-based Networks\u27\u27 was held
in the International Conference and Research Center (IBFI), Schloss Dagstuhl.
During the seminar, several participants presented their current
research, and ongoing work and open problems were discussed. Abstracts of
the presentations given during the seminar as well as abstracts of
seminar results and ideas are put together in this paper. The first section
describes the seminar topics and goals in general.
Links to extended abstracts or full papers are provided, if available
Roles played by relational trust in strategic alliances
In this paper we develop the concept of relational quality as a proxy for relational trust. Exploration of data from 67 alliances confirms that relational quality is composed of three elements: initial conditions, partner interactions, and external events. We offer propositions on the relative importance of each of these elements depending on the different roles relational trust may play in strategic alliances: the role of a control mechanism, of a governance mechanism, or as an enabler of high risk initiativesManagement; Strategy
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