Search results for "Distributed computing"
showing 10 items of 622 documents
Graph-grammar semantics of a higher-order programming language for distributed systems
1994
We will consider a new tiny, yet powerful, programming language for distributed systems, called DHOP, which has its operational semantics given as algebraic graph rewrite rules in a certain category of labeled graphs. Our approach allows to separate actions which affect several processes from local changes such as variable bindings. We also sketch how to derive an implementation from this specification.
AMCAS: Advanced Methods for the Co-Design of Complex Adaptive Systems
2006
Abstract This work proposes a new approximation to design and program Complex Adaptive Systems (CAS), these systems comprise neural network, intelligent agents, genetic algorithms, support vector machines and artificial intelligence systems in general. Due to the complexity of such systems, it is necessary to build a design environment able to ease the design work, allowing reusability and easy migration to hardware and/or software. Ptolemy II is used as the base system to simulate and evaluate the designs with different Models of Computation so that an optimum decision about the hardware or software implementation platform can be taken.
Deployment of a WLCG network monitoring infrastructure based on the perfSONAR-PS technology
2014
The WLCG infrastructure moved from a very rigid network topology, based on the MONARC model, to a more relaxed system, where data movement between regions or countries does not necessarily need to involve T1 centres. While this evolution brought obvious advantages, especially in terms of flexibility for the LHC experiment's data management systems, it also opened the question of how to monitor the increasing number of possible network paths, in order to provide a global reliable network service. The perfSONAR network monitoring system has been evaluated and agreed as a proper solution to cover the WLCG network monitoring use cases: it allows WLCG to plan and execute latency and bandwidth te…
Rethinking the IEEE 802.11e EDCA Performance Modeling Methodology
2010
Analytical modeling of the 802.11e enhanced distributed channel access (EDCA) mechanism is today a fairly mature research area, considering the very large number of papers that have appeared in the literature. However, most work in this area models the EDCA operation through per-slot statistics, namely probability of transmission and collisions referred to "slots." In so doing, they still share a methodology originally proposed for the 802.11 Distributed Coordination Function (DCF), although they do extend it by considering differentiated transmission/ collision probabilities over different slots.We aim to show that it is possible to devise 802.11e models that do not rely on per-slot statis…
Assessing the effectiveness of IEEE 802.11e in multi-hop mobile network environments
2004
The IEEE 802.11e technology is receiving much interest due to the promising enhancements it offers to wireless local area networks in terms of QoS support. Until now, research has focused on single hop, access point based environments, which are the most common. We review the enhancements proposed in the last IEEE 802.11e draft (version 8.0). We analyze the performance of the IEEE 802.11e protocol on ad-hoc networks (multi-hop) in terms of throughput and end-to-end delay. We also measure the effectiveness for static and fully dynamic networks with a variable number of source stations. Finally, we analyze the performance of IEEE 802.11e when legacy IEEE 802.11 stations (no IEEE 802.11e suppo…
Capacity and Energy-Consumption Optimization for the Cluster-Tree Topology in IEEE 802.15.4
2011
International audience; 802.15.4 proposes to use a cluster-tree hierar- chy to organize the transmissions in Wireless Sensor Networks. In this letter, we propose a framework to analyze formally the capacity and the energy consumption of this structure. We derive a Mixed Integer Linear Programming (MILP) formulation to obtain a topology compliant with the standard. This formulation provides the optimal solution for the network capacity: this con- stitutes an upper bound for any distributed algorithms permitting to construct a cluster-tree. This framework can also be used to evaluate the capacity and to compare quantitatively different cluster-tree algorithms.
Experimental realization of a Persistent Identifier Infrastructure stack for Named Data Networking
2015
The continuation of Persistent Identifier Infrastructures is crucial when next-generation Internet architectures based on Information-Centric Networking (ICN) arise. When moving to ICN, we must ensure the resolution of Persistent Identifiers (PID), such as the billions of Digital Object Identifiers (DOI) used today, to provide continued access to scientific literature and research data. It provides the base for the necessary transformations in the Handle System architecture and protocol for running a PID system on the Named Data Networking (NDN) architecture, which is a recent incarnation of ICN. Furthermore, it examines the PID-specific resolution access patterns, investigates the expected…
The Design of Secure and Efficient P2PSIP Communication Systems
2010
Recently, both academia and industry have initiated research projects directed on integration of P2PSIP paradigm into communication systems. In this paradigm, P2P network stores most of the network information among participating peers without help of the central servers. The concept of self-configuration, self-establishment greatly improves the robustness of the network system compared with the traditional Client/Server based systems. In this paper, we propose a system architecture for constructing efficient and secure P2PSIP communication systems. The proposed approach includes three-layer hierarchical overlay division, peer identifier assignment, cache based efficiency enhancement, proxy…
Dissensus, death and division
2009
The modeling of switching systems describing networks where death and duplication processes occur is described. A dissensus protocol, complementary to consensus protocol, is introduced and the convergence or divergence of the agents' state evolution is studied. We discuss some properties of the topology reached by the network when different rules of duplication and inheritance are implemented.
Computing Real-Time Dynamic Origin/Destination Matrices from Vehicle-to-Infrastructure Messages Using a Multi-Agent System
2012
Dynamic Origin/Destination matrices are one of the most important parameters for efficient and effective transportation system management. These matrices describe the vehicle flow between different points within a region of interest for a given period of time. Usually, dynamic O/D matrices are estimated from traffic counts provided by induction loop detectors, home interview and/or license plate surveys. Unfortunately, estimation methods take O/D flows as time invariant for a certain number of intervals of time, which cannot be suitable for some traffic applications. However, the advent of information and communication technologies (e.g., vehicle-to-infrastructure dedicated short range comm…