Intelligent query processing in P2P networks: semantic issues and routing algorithms

P2P networks have become a commonly used way of disseminating content on the Internet. In this context, constructing efficient and distributed P2P routing algorithms for complex environments that include a huge number of distributed nodes with different computing and network capabilities is a major challenge. In the last years, query routing algorithms have evolved by taking into account different features (provenance, nodes' history, topic similarity, etc.). Such features are usually stored in auxiliary data structures (tables, matrices, etc.), which provide an extra knowledge engineering layer on top of the network, resulting in an added semantic value for specifying algorithms for efficient query routing. This article examines the main existing algorithms for query routing in unstructured P2P networks in which semantic aspects play a major role. A general comparative analysis is included, associated with a taxonomy of P2P networks based on their degree of decentralization and the different approaches adopted to exploit the available semantic aspects.Fil: Nicolini, Ana Lucía. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Ciencias e Ingeniería de la Computación. Universidad Nacional del Sur. Departamento de Ciencias e Ingeniería de la Computación. Instituto de Ciencias e Ingeniería de la Computación; ArgentinaFil: Lorenzetti, Carlos Martin. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Ciencias e Ingeniería de la Computación. Universidad Nacional del Sur. Departamento de Ciencias e Ingeniería de la Computación. Instituto de Ciencias e Ingeniería de la Computación; ArgentinaFil: Maguitman, Ana Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Ciencias e Ingeniería de la Computación. Universidad Nacional del Sur. Departamento de Ciencias e Ingeniería de la Computación. Instituto de Ciencias e Ingeniería de la Computación; ArgentinaFil: Chesñevar, Carlos Iván. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Ciencias e Ingeniería de la Computación. Universidad Nacional del Sur. Departamento de Ciencias e Ingeniería de la Computación. Instituto de Ciencias e Ingeniería de la Computación; Argentin

Logical Networks: Self-organizing Overlay Networks and Overlay Computing Systems: [EPI Proposal V2.0]

Contents 1 Team on March 15, 2010 ...........................................42 Capsule ...........................................52.1 Slogan and logo............................................ 5 2.2 One equation fits all and keywords ................................. 6 2.3 How to read this proposal ...................................... 63 Vertical view ...........................................63.1 Panorama............................................... 6 3.2 General definitions .......................................... 8 3.3 Virtual organization ......................................... 9 3.4 Execution model ........................................... 94 Horizontal view ...............................................94.1 Panorama............................................... 94.2 Arigatoni overlay network ...................................... 10 4.2.1 Arigatoni units........................................ 10 4.2.2 Virtual organizations in Arigatoni ............................. 12 4.2.3 Resource discovery protocol (RDP)............................. 12 4.2.4 Virtual Intermittent Protocol (VIP) ............................ 13 4.2.5 iNeu: librairies for network computing........................... 144.3 Babelchord, a DHT’s tower ..................................... 144.4 Synapse,interconnecting heterogeneous overlay networks. . . . . . . . . . . . . . . . . . . . . 154.5 Cross-layer overlay design for geo-sensible applications . . . . . . . . . . . . . . . . . . . . . . 175 Diagonal view...............................................175.1 Panorama............................................... 17 5.2 Trees versus graphs: a conflict without a cause .......................... 17 5.3 Fault tolerance ............................................ 18 5.4 Parametricity and universality ................................... 18 5.5 Social networking........................................... 19 5.6 Choice of development platform................................... 19 5.7 Quality metrics for an overlay computer .............................. 19 5.8 Trust and security .......................................... 20 5.9 New models of computations .................................... 216 Topics and time line...............................................226.1 Panorama............................................... 226.2 Topicview............................................... 22 6.2.1 Vertical issues......................................... 22 6.2.2 Horizontal issues ....................................... 22 6.2.3 Diagonalissues........................................ 236.3 Timeview............................................... 23 6.3.1 Short-term .......................................... 23 6.3.2 Medium-term......................................... 24 6.3.3 Long-term........................................... 247 Potential application domains ...........................................247.1 Panorama............................................... 24 7.2 P2P social networks ......................................... 25 7.3 Overlay computer for mobile ad hoc networks........................... 25 7.4 OverStic: the mesh overlay network in Sophia Antipolis ..................... 27 7.5 Reducing the Digital Divide..................................... 28 7.6 GRID applications: scenario for seismic monitoring ....................... 29 7.7 Interconnection of heterogeneous overlay networks ........................ 30 7.8 Toward an overlay network of things (RFID) ........................... 318 Software ...........................................328.1 Panorama............................................... 328.2 Prototype software.......................................... 32 8.2.1 Arigatoni simulator ..................................... 32 8.2.2 Ariwheels........................................... 32 8.2.3 BabelChord.......................................... 36 8.2.4 Synapse............................................ 37 8.2.5 Open-Synapse Client..................................... 38 8.2.6 myTransport Gui....................................... 39 8.2.7 CarPal: a P2P carpooling service ............................. 39 8.2.8 Husky interpreter....................................... 408.3 Potential software .......................................... 41 8.3.1 myMed (in french), see http://www-sop.inria.fr/mymed . . . . . . . . . . . . . . . . 419 Contracts...........................................439.1 INTERREG Alcotra: myMed,2010-2013.............................. 43 9.2 COLOR:JMED,2010 ........................................ 43 9.3 FP6 FET GlobalComputing: IST AEOLUS, 2006-2010 ..................... 43 9.4 JET TEMPUS DEUKS, 2007-2009................................. 4410 Collaborations ...........................................4411 Self assessment ...........................................4411.1 Trivia ................................................. 45 11.2 Conclusions.............................................. 45We propose foundations for generic overlay networks and overlay computing systems. Such overlays are built over a large number of distributed computational agents, virtually organized in colonies or virtual organizations, and ruled by a leader (broker) who is elected democratically (vox populi, vox dei) or imposed by system administrators (primus inter pares). Every agent asks the broker to log in the colony by declaring the resources that can be offered (with variable guarantees). Once logged in, an agent can ask the broker for other resources. Colonies can recursively be considered as evolved agents who can log in an outermost colony governed by another super-leader. Communications and routing intra-colonies goes through a broker-2-broker PKI-based negotiation. Every broker routes intra- and inter- service requests by filtering its resource routing table, and then forwarding the request first inside its colony, and second outside, via the proper super-leader (thus applying an endogenous-first-estrogen- last strategy). Theoretically, queries are formulæ in first-order logic equipped with a small program used to orchestrate and synchronize atomic formulæ (atomic services). When the client agent receives notification of all (or part of) the requested resources, then the real resource exchange is performed directly by the server(s) agents, without any further mediation of the broker, in a pure peer-to-peer fashion. The proposed overlay promotes an intermittent participation in the colony, since peers can appear, disappear, and organize themselves dynamically. This implies that the routing process may lead to failures, because some agents have quit or are temporarily unavailable, or they were logged out manu militari by the broker due to their poor performance or greediness. We aim to design, validate through simulation, and implement these foundations in an overlay network computer system. (From [Liquori-Cosnard TGC-07 paper])

Découverte et allocation des ressources pour le traitement de requêtes dans les systèmes grilles

De nos jours, les systèmes Grille, grâce à leur importante capacité de calcul et de stockage ainsi que leur disponibilité, constituent l'un des plus intéressants environnements informatiques. Dans beaucoup de différents domaines, on constate l'utilisation fréquente des facilités que les environnements Grille procurent. Le traitement des requêtes distribuées est l'un de ces domaines où il existe de grandes activités de recherche en cours, pour transférer l'environnement sous-jacent des systèmes distribués et parallèles à l'environnement Grille. Dans le cadre de cette thèse, nous nous concentrons sur la découverte des ressources et des algorithmes d'allocation de ressources pour le traitement des requêtes dans les environnements Grille. Pour ce faire, nous proposons un algorithme de découverte des ressources pour le traitement des requêtes dans les systèmes Grille en introduisant le contrôle de topologie auto-stabilisant et l'algorithme de découverte des ressources dirigé par l'élection convergente. Ensuite, nous présentons un algorithme d'allocation des ressources, qui réalise l'allocation des ressources pour les requêtes d'opérateur de jointure simple par la génération d'un espace de recherche réduit pour les nœuds candidats et en tenant compte des proximités des candidats aux sources de données. Nous présentons également un autre algorithme d'allocation des ressources pour les requêtes d'opérateurs de jointure multiple. Enfin, on propose un algorithme d'allocation de ressources, qui apporte une tolérance aux pannes lors de l'exécution de la requête par l'utilisation de la réplication passive d'opérateurs à état. La contribution générale de cette thèse est double. Premièrement, nous proposons un nouvel algorithme de découverte de ressource en tenant compte des caractéristiques des environnements Grille. Nous nous adressons également aux problèmes d'extensibilité et de dynamicité en construisant une topologie efficace sur l'environnement Grille et en utilisant le concept d'auto-stabilisation, et par la suite nous adressons le problème de l'hétérogénéité en proposant l'algorithme de découverte de ressources dirigé par l'élection convergente. La deuxième contribution de cette thèse est la proposition d'un nouvel algorithme d'allocation des ressources en tenant compte des caractéristiques de l'environnement Grille. Nous abordons les problèmes causés par la grande échelle caractéristique en réduisant l'espace de recherche pour les ressources candidats. De ce fait nous réduisons les coûts de communication au cours de l'exécution de la requête en allouant des nœuds au plus près des sources de données. Et enfin nous traitons la dynamicité des nœuds, du point de vue de leur existence dans le système, en proposant un algorithme d'affectation des ressources avec une tolérance aux pannes.Grid systems are today's one of the most interesting computing environments because of their large computing and storage capabilities and their availability. Many different domains profit the facilities of grid environments. Distributed query processing is one of these domains in which there exists large amounts of ongoing research to port the underlying environment from distributed and parallel systems to the grid environment. In this thesis, we focus on resource discovery and resource allocation algorithms for query processing in grid environments. For this, we propose resource discovery algorithm for query processing in grid systems by introducing self-stabilizing topology control and converge-cast based resource discovery algorithms. Then, we propose a resource allocation algorithm, which realizes allocation of resources for single join operator queries by generating a reduced search space for the candidate nodes and by considering proximities of candidates to the data sources. We also propose another resource allocation algorithm for queries with multiple join operators. Lastly, we propose a fault-tolerant resource allocation algorithm, which provides fault-tolerance during the execution of the query by the use of passive replication of stateful operators. The general contribution of this thesis is twofold. First, we propose a new resource discovery algorithm by considering the characteristics of the grid environments. We address scalability and dynamicity problems by constructing an efficient topology over the grid environment using the self-stabilization concept; and we deal with the heterogeneity problem by proposing the converge-cast based resource discovery algorithm. The second main contribution of this thesis is the proposition of a new resource allocation algorithm considering the characteristics of the grid environment. We tackle the scalability problem by reducing the search space for candidate resources. We decrease the communication costs during the query execution by allocating nodes closer to the data sources. And finally we deal with the dynamicity of nodes, in terms of their existence in the system, by proposing the fault-tolerant resource allocation algorithm

Barriers and facilitators to accessing and utilising post-treatment psychosocial support by Black men treated for prostate cancer—a systematic review and qualitative synthesis

Purpose: To synthesise findings from published studies on barriers and facilitators to Black men accessing and utilising post-treatment psychosocial support after prostate cancer (CaP) treatment. Methods: Searches of Medline, Embase, PsycInfo, Cochrane Database of Systematic Reviews and Central, CINAHL plus and Scopus were undertaken from inception to May 2021. English language studies involving Black men aged ≥18 and reporting experiences of, or suggestions for, psychosocial support after CaP treatment were included. Low or moderate quality studies were excluded. Searches identified 4,453 articles and following deduplication, 2,325 were screened for eligibility. Two independent reviewers carried out screening, quality appraisal and data extraction. Data were analysed using thematic synthesis. Results: Ten qualitative studies involving 139 Black men were included. Data analysis identified four analytical constructs: experience of psychosocial support for dealing with treatment side effects (including impact on self-esteem and fear of recurrence); barriers to use of psychosocial support (such as perceptions of masculinity and stigma around sexual dysfunction); facilitators to use of psychosocial support (including the influence of others and self-motivation); and practical solutions for designing and delivering post-treatment psychosocial support (the need for trusted healthcare and cultural channels). Conclusions: Few intervention studies have focused on behaviours among Black CaP survivors, with existing research predominantly involving Caucasian men. There is a need for a collaborative approach to CaP care that recognises not only medical expertise but also the autonomy of Black men as experts of their illness experience, and the influence of cultural and social networks

CHORUS Deliverable 2.2: Second report - identification of multi-disciplinary key issues for gap analysis toward EU multimedia search engines roadmap

After addressing the state-of-the-art during the first year of Chorus and establishing the existing landscape in multimedia search engines, we have identified and analyzed gaps within European research effort during our second year. In this period we focused on three directions, notably technological issues, user-centred issues and use-cases and socio- economic and legal aspects. These were assessed by two central studies: firstly, a concerted vision of functional breakdown of generic multimedia search engine, and secondly, a representative use-cases descriptions with the related discussion on requirement for technological challenges. Both studies have been carried out in cooperation and consultation with the community at large through EC concertation meetings (multimedia search engines cluster), several meetings with our Think-Tank, presentations in international conferences, and surveys addressed to EU projects coordinators as well as National initiatives coordinators. Based on the obtained feedback we identified two types of gaps, namely core technological gaps that involve research challenges, and “enablers”, which are not necessarily technical research challenges, but have impact on innovation progress. New socio-economic trends are presented as well as emerging legal challenges

Incentive-driven QoS in peer-to-peer overlays

A well known problem in peer-to-peer overlays is that no single entity has control over the software, hardware and configuration of peers. Thus, each peer can selfishly adapt its behaviour to maximise its benefit from the overlay. This thesis is concerned with the modelling and design of incentive mechanisms for QoS-overlays: resource allocation protocols that provide strategic peers with participation incentives, while at the same time optimising the performance of the peer-to-peer distribution overlay. The contributions of this thesis are as follows. First, we present PledgeRoute, a novel contribution accounting system that can be used, along with a set of reciprocity policies, as an incentive mechanism to encourage peers to contribute resources even when users are not actively consuming overlay services. This mechanism uses a decentralised credit network, is resilient to sybil attacks, and allows peers to achieve time and space deferred contribution reciprocity. Then, we present a novel, QoS-aware resource allocation model based on Vickrey auctions that uses PledgeRoute as a substrate. It acts as an incentive mechanism by providing efficient overlay construction, while at the same time allocating increasing service quality to those peers that contribute more to the network. The model is then applied to lagsensitive chunk swarming, and some of its properties are explored for different peer delay distributions. When considering QoS overlays deployed over the best-effort Internet, the quality received by a client cannot be adjudicated completely to either its serving peer or the intervening network between them. By drawing parallels between this situation and well-known hidden action situations in microeconomics, we propose a novel scheme to ensure adherence to advertised QoS levels. We then apply it to delay-sensitive chunk distribution overlays and present the optimal contract payments required, along with a method for QoS contract enforcement through reciprocative strategies. We also present a probabilistic model for application-layer delay as a function of the prevailing network conditions. Finally, we address the incentives of managed overlays, and the prediction of their behaviour. We propose two novel models of multihoming managed overlay incentives in which overlays can freely allocate their traffic flows between different ISPs. One is obtained by optimising an overlay utility function with desired properties, while the other is designed for data-driven least-squares fitting of the cross elasticity of demand. This last model is then used to solve for ISP profit maximisation

CHORUS Deliverable 2.1: State of the Art on Multimedia Search Engines

Based on the information provided by European projects and national initiatives related to multimedia search as well as domains experts that participated in the CHORUS Think-thanks and workshops, this document reports on the state of the art related to multimedia content search from, a technical, and socio-economic perspective. The technical perspective includes an up to date view on content based indexing and retrieval technologies, multimedia search in the context of mobile devices and peer-to-peer networks, and an overview of current evaluation and benchmark inititiatives to measure the performance of multimedia search engines. From a socio-economic perspective we inventorize the impact and legal consequences of these technical advances and point out future directions of research

Survey of Models and Architectures to Ensure Linked Data Access

Mobile Access to the Web of Data is currently a real challenge in developing countries, mainly characterized by limited Internet connectivity and high penetration of mobile devices with the limited resources (such as cache and memory). In this paper, we survey and compare proposed solutions (such as models and architectures) that could contribute to solving this problem of mobile access to the Web of Data with intermittent Internet access. These solutions are discussed in relation to the underlying network architectures and data models considered. We present a conceptual study of peer-to-peer solutions based on gossip protocols dedicated to design the connected overlay networks. In addition, we provide a detailed analysis of client-server and data replication systems generally designed to ensure the local availability of data on the system. We conclude with some recommendations to achieve a connected architecture that provides mobile contributors with local access to the Web of data