Extending JXTA for P2P File Sharing Systems

File sharing is among the most important features of the today’s Internet-based applications. Most of such applications are server-based approaches inheriting thus the disadvantages of centralized systems. Advances in P2P systems are allowing to share huge quantities of data and files in a distributed way. In this paper, we present extensions of JXTA protocols to support file sharing in P2P systems with the aim to overcome limitations of server-mediated approaches. Our proposal is validated in practice by deploying a P2P file sharing system in a real P2P network.The empirical study revealed the benefits and drawbacks of using JXTA protocol for P2P file sharing systems.one of the most important concern

Benefits of an Implementation of H-P2PSIP

[Paper presented at:] Second International Conference on Advances in P2P Systems. AP2PS 2010. October 25-30, Florence (Italy)In this paper, we report on the results of experiments with an implementation of H-P2PSIP, which allows the exchange of information among different DHTs (Distributed Hash Tables) making use of a hierarchical architecture. This paper validates our previous H-P2PSIP proposal in an environment with a real TCP/IP stack close to a real scenario. The results show how the benefits of this real H-P2PSIP implementation in terms of routing performance (number of hops), delay and routing state (number of routing entries) are better than a flat DHT overlay network and how the exchange of information among different DHT overlay networks is feasible.This work has been supported by the FP7 TREND Grant (agreement No. 257740) and by the Regional Government of Madrid under the MEDIANET project (CAM, S2009/TIC-1468).European Community's Seventh Framework ProgramPublicad

Effectiveness of landmark analysis for establishing locality in p2p networks

Locality to other nodes on a peer-to-peer overlay network can be established by means of a set of landmarks shared among the participating nodes. Each node independently collects a set of latency measures to landmark nodes, which are used as a multi-dimensional feature vector. Each peer node uses the feature vector to generate a unique scalar index which is correlated to its topological locality. A popular dimensionality reduction technique is the space filling Hilbert’s curve, as it possesses good locality preserving properties. However, there exists little comparison between Hilbert’s curve and other techniques for dimensionality reduction. This work carries out a quantitative analysis of their properties. Linear and non-linear techniques for scaling the landmark vectors to a single dimension are investigated. Hilbert’s curve, Sammon’s mapping and Principal Component Analysis have been used to generate a 1d space with locality preserving properties. This work provides empirical evidence to support the use of Hilbert’s curve in the context of locality preservation when generating peer identifiers by means of landmark vector analysis. A comparative analysis is carried out with an artificial 2d network model and with a realistic network topology model with a typical power-law distribution of node connectivity in the Internet. Nearest neighbour analysis confirms Hilbert’s curve to be very effective in both artificial and realistic network topologies. Nevertheless, the results in the realistic network model show that there is scope for improvements and better techniques to preserve locality information are required

Event-Cloud Platform to Support Decision- Making in Emergency Management

The challenge of this paper is to underline the capability of an Event-Cloud Platform to support efficiently an emergency situation. We chose to focus on a nuclear crisis use case. The proposed approach consists in modeling the business processes of crisis response on the one hand, and in supporting the orchestration and execution of these processes by using an Event-Cloud Platform on the other hand. This paper shows how the use of Event-Cloud techniques can support crisis management stakeholders by automatizing non-value added tasks and by directing decision- makers on what really requires their capabilities of choice. If Event-Cloud technology is a very interesting and topical subject, very few research works have considered this to improve emergency management. This paper tries to fill this gap by considering and applying these technologies on a nuclear crisis use-case