Search results for "distributed system"

A secure architecture for P2PSIP-based communication systems

2009

Today, Peer-to-Peer SIP based communication systems have attracted much attention from both academia and industry. The decentralized nature of P2P might provide the distributed peer-to-peer communication system without help of the traditional SIP server. However, it comes to the cost of reduced manageability and therefore causes security problems, e.g. distrust, privacy leaks, unpredictable availability, etc. In this paper, we investigate on P2PSIP security issues and propose a proxy-based system architecture that improves security during P2PSIP session initiation. The main issues considered in this architecture include Source inter-working, Encryption & Decryption, Policy Management, Desti…

Broadband Internet Access via Multi-Hop Wireless Mesh Networks: Design, Protocol and Experiments

2010

Published version of an article from the journal: Wireless Personal Communications. The original publication is available at Spingerlink. http://dx.doi.org/10.1007/s11277-009-9907-9 While bandwidth for Internet access in urban areas is steadily increasing in recent years, many rural areas are still suffering from the effect of the digital divide. This paper presents a broadband Internet access paradigm developed in the context of the ADHOCSYS project, which was financed by the European Commission under the 6th Framework Program Information and Society Technologies, within the strategic objective of Broadband for All. Aiming at providing reliable Internet access in rural and mountainous regi…

A symbolic distributed event detection scheme for Wireless Sensor Networks

2016

Due to the possibility of extensive and pervasive deployment of many tiny sensor devices in the area of interest, Wireless Sensor Networks (WSNs) result particularly suitable to detect significant events and to react accordingly in industrial and home scenarios. In this context, fuzzy inference systems for event detection in WSNs have proved to be accurate enough in treating imprecise sensory readings to decrease the number of false alarms. Besides reacting to event occurrences, the whole network may infer more information to enrich the event semantics resulting from reasoning processes carried out on the individual nodes. Contextual knowledge, including spatial and temporal relationships, …

An Integrated Environment for Dynamic Processes in distributed Image Analysis System

1998

Distributed systems, sharing same network, are composed by multiple high-performance microcomputers. To improve the performance of such system is necessary to distribute the occurred processes following a suitable approach. To do that, a set of parameters and two composed objects (Tablet and Bonnet: in brief, an extended task and an asynchronous worker respectively) have been defined to satisfy the distribution the tasks. These objects allow to arrange the distribution of processes and data, on the processors, in static and dynamic way. An high level interactive iconic environment, with a set of visual tools, has been developed to improve the management of the resource and to execute the ac…

Logical Consensus for Distributed Network Agreement

2008

In this paper we introduce a novel consensus mechanism where agents of a network are able to share logical values, or Booleans, representing their local opinions on e.g. the presence of an intruder or of a fire within an indoor environment. Under suitable joint conditions on agents? visibility and communication capability, we provide an algorithm generating a logical linear consensus system that is globally stable. The solution is optimal in terms of the number of messages to be exchanged and the time needed to reach a consensus. Moreover, to cope with possible sensor failure, we propose a second design approach that produces robust logical nonlinear consensus systems tolerating a maximum n…

Symbolic Programming of Distributed Cyber-Physical Systems

Cyber-Physical Systems (CPSs) tightly integrate physical world phenomena and cyber aspects of computational units. The composition of physical, computational and communication systems demands different levels and types of abstraction as well as novel programming methodologies allowing for homogeneous programming, knowledge representation and exchange on heterogeneous devices. Current modeling approaches, frameworks and architectures result fairly inadequate to the task, especially when resource-constrained devices are involved. This work proposes symbolic computation as an effective solution to program resource constrained CPS devices with code maintaining strict ties to high-level specific…

Testing wearable IoT applications through sensor virtualization

2020

The development of distributed IoT applications requires the integration of data provided by different sensors embedded in multiple devices. As an example, an application for health monitoring in an assisted living scenario may include several wearable and fixed nodes each carrying different sensors and running specific code. Verifying that the application is properly working according to the specifications requires assessing that the code of each node behaves consistently in all the possible use cases. Tests involving sensor data may be difficult or costly to replicate realistically and this could also slow down the development of the application in its early stages. In this paper we intro…

Reputation management in distributed systems

2008

Several distributed applications, implemented over today’s Internet, are based on the assumption that participating agents collaborate in order to achieve their own goal. However, when these applications are modelled as unstructured distributed systems, the greater autonomy and decentralization encourage antisocial behaviours, which are likely to cause performance degradation for the whole system. This paper presents a fully distributed reputation management system that allows the evaluation of agent reputation in unstructured environments without any centralized coordination. The proposed approach is based on game theory and is capable of capturing the highly dynamic nature of the involved…

A Simulation Software for the Evaluation of Vulnerabilities in Reputation Management Systems

2019

Multi-agent distributed systems are characterized by autonomous entities that interact with each other to provide, and/or request, different kinds of services. In several contexts, especially when a reward is offered according to the quality of service, individual agents (or coordinated groups) may act in a selfish way. To prevent such behaviours, distributed Reputation Management Systems (RMSs) provide every agent with the capability of computing the reputation of the others according to direct past interactions, as well as indirect opinions reported by their neighbourhood. This last point introduces a weakness on gossiped information that makes RMSs vulnerable to malicious agents’ intent …

Work Partitioning on Parallel and Distributed Agent-Based Simulation

2017

Work partitioning is a key challenge with ap- plications in many scientific and technological fields. The problem is very well studied with a rich literature on both distributed and parallel computing architectures. In this paper we deal with the work partitioning problem for parallel and distributed agent-based simulations which aims at (i) balancing the overall load distribution, (ii) minimizing, at the same time, the communication overhead due to agents' inter-dependencies. We introduce a classification taxonomy of work partitioning strategies and present a space-based work partitioning ap- proach, based on a Quad-tree data structure, which enables to: identify a good space partitioning …