2,617 research outputs found
2 P2P or Not 2 P2P?
In the hope of stimulating discussion, we present a heuristic decision tree
that designers can use to judge the likely suitability of a P2P architecture
for their applications. It is based on the characteristics of a wide range of
P2P systems from the literature, both proposed and deployed.Comment: 6 pages, 1 figur
Data storage solutions for the federation of sensor networks
In the near future, most of our everyday devices will be accessible via some
network and uniquely identified for interconnection over the Internet. This
new paradigm, called Internet of Things (IoT), is already starting to influence
our society and is now driving developments in many areas.
There will be thousands, or even millions, of constrained devices that will
be connected using standard protocols, such as Constrained Application Protocol
(CoAP), that have been developed under certain specifications appropriate
for this type of devices. In addition, there will be a need to interconnect
networks of constrained devices in a reliable and scalable way, and federations
of sensor networks using the Internet as a medium will be formed.
To make the federation of geographically distributed CoAP based sensor
networks possible, a CoAP Usage for REsource LOcation And Discovery (RELOAD)
was recently proposed. RELOAD is a peer-to-peer (P2P) protocol that
ensures an abstract storage and messaging service to its clients, and it relies
on a set of cooperating peers that form a P2P overlay network for this purpose.
This protocol allows to define so-called Usages for applications to work
on top of this overlay network. The CoAP Usage for RELOAD is, therefore,
a way for CoAP based devices to store their resources in a distributed P2P
overlay. Although CoAP Usage for RELOAD is an important step towards
the federation of sensor networks, in the particular case of IoT there will be
consistency and efficiency problems. This happens because the resources of
CoAP devices/Things can be in multiple data objects stored at the overlay network,
called P2P resources. Thus, Thing resource updates can end up being
consuming, as multiple P2P resources will have to be modified. Mechanisms
to ensure consistency become, therefore, necessary.
This thesis contributes to advances in the federation of sensor networks by
proposing mechanisms for RELOAD/CoAP architectures that will allow consistency
to be ensured. An overlay network service, required for such mechanisms
to operate, is also proposed.Num futuro próximo, a maioria dos nossos dispositivos do dia-a-dia estarão
acessíveis através de uma rede e serão identificados de forma única para
poderem interligar-se através da Internet. Este novo paradigma, conhecido
hoje por Internet das Coisas (IoT), já está a começar a influenciar a nossa
sociedade e está agora a impulsionar desenvolvimentos em inúmeras áreas.
Teremos milhares, ou mesmo milhões, de dispositivos restritos que utilizarão protocolos padrão que foram desenvolvidos de forma a cumprir determinadas
especificações associadas a este tipo de dispositivos, especificações essas
que têm a ver com o facto destes dispositivos terem normalmente restrições
de memória, pouca capacidade de processamento e muitos possuirem limitações
energéticas. Surgirá ainda a necessidade de interligar, de forma fiável e
escalonável, redes de dispositivos restritos.(…
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
A Case for Cooperative and Incentive-Based Coupling of Distributed Clusters
Research interest in Grid computing has grown significantly over the past
five years. Management of distributed resources is one of the key issues in
Grid computing. Central to management of resources is the effectiveness of
resource allocation as it determines the overall utility of the system. The
current approaches to superscheduling in a grid environment are non-coordinated
since application level schedulers or brokers make scheduling decisions
independently of the others in the system. Clearly, this can exacerbate the
load sharing and utilization problems of distributed resources due to
suboptimal schedules that are likely to occur. To overcome these limitations,
we propose a mechanism for coordinated sharing of distributed clusters based on
computational economy. The resulting environment, called
\emph{Grid-Federation}, allows the transparent use of resources from the
federation when local resources are insufficient to meet its users'
requirements. The use of computational economy methodology in coordinating
resource allocation not only facilitates the QoS based scheduling, but also
enhances utility delivered by resources.Comment: 22 pages, extended version of the conference paper published at IEEE
Cluster'05, Boston, M
Dynamic load balancing for the distributed mining of molecular structures
In molecular biology, it is often desirable to find common properties in large numbers of drug candidates. One family of
methods stems from the data mining community, where algorithms to find frequent graphs have received increasing attention over the
past years. However, the computational complexity of the underlying problem and the large amount of data to be explored essentially
render sequential algorithms useless. In this paper, we present a distributed approach to the frequent subgraph mining problem to
discover interesting patterns in molecular compounds. This problem is characterized by a highly irregular search tree, whereby no
reliable workload prediction is available. We describe the three main aspects of the proposed distributed algorithm, namely, a dynamic
partitioning of the search space, a distribution process based on a peer-to-peer communication framework, and a novel receiverinitiated
load balancing algorithm. The effectiveness of the distributed method has been evaluated on the well-known National Cancer
Institute’s HIV-screening data set, where we were able to show close-to linear speedup in a network of workstations. The proposed
approach also allows for dynamic resource aggregation in a non dedicated computational environment. These features make it suitable
for large-scale, multi-domain, heterogeneous environments, such as computational grids
Resilient availability and bandwidth-aware multipath provisioning for media transfer over the internet (Best Paper Award)
Traditional routing in the Internet is best-effort. Path differentiation including multipath routing is a promising technique to be used for meeting QoS requirements of media intensive applications. Since different paths have different characteristics in terms of latency, availability and bandwidth, they offer flexibility in QoS and congestion control. Additionally protection techniques can be used to enhance the reliability of the network.
This paper studies the problem of how to optimally find paths ensuring maximal bandwidth and resiliency of media transfer over the network. In particular, we propose two algorithms to reserve network paths with minimal new resources while increasing the availability of the paths and enabling congestion control. The first algorithm is based on Integer Linear Programming which minimizes the cost of the paths and the used resources. The second one is a heuristic-based algorithm which solves the scalability limitations of the ILP approach. The algorithms ensure resiliency against any single link failure in the network.
The experimental results indicate that using the proposed schemes the connections availability improve significantly and a more balanced load is achieved in the network compared to the shortest path-based approaches
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Self-organizing peer-to-peer social networks
This is the author's accepted manuscript. The final published article is available from the link below. Copyright @ 2008 The Authors.Peer-to-peer (P2P) systems provide a new solution to distributed information and resource sharing because of its outstanding properties in decentralization, dynamics, flexibility, autonomy, and cooperation, summarized as DDFAC in this paper. After a detailed analysis of the current P2P literature, this paper suggests to better exploit peer social relationships and peer autonomy to achieve efficient P2P structure design. Accordingly, this paper proposes Self-organizing peer-to-peer social networks (SoPPSoNs) to self-organize distributed peers in a decentralized way, in which neuron-like agents following extended Hebbian rules found in the brain activity represent peers to discover useful peer connections. The self-organized networks capture social associations of peers in resource sharing, and hence are called P2P social networks. SoPPSoNs have improved search speed and success rate as peer social networks are correctly formed. This has been verified through tests on real data collected from the Gnutella system. Analysis on the Gnutella data has verified that social associations of peers in reality are directed, asymmetric and weighted, validating the design of SoPPSoN. The tests presented in this paper have also evaluated the scalability of SoPPSoN, its performance under varied initial network connectivity and the effects of different learning rules.National Natural Science of Foundation of Chin
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