Vignette d'image

Schiavoni, Valerio

Nom
Schiavoni, Valerio
Affiliation principale
Site web
Fonction
Maitre-Assistant, Coordinateur Complex Systems and Big Data Competence Centre
Email
valerio.schiavoni@unine.ch
Identifiants
https://libra.unine.ch/handle/123456789/293
_
0000-0003-1493-6603

Résultat de la recherche

Filtres

3
3
Réinitialiser les filtres

Paramètres

Voici les éléments 1 - 3 sur 3
  • Publication
    Métadonnées seulement
    Lightweight, Efficient, Robust Epidemic Dissemination
    (2013-1-13)
    Matos, Miguel
    ;
    Schiavoni, Valerio 
    ;
    Felber, Pascal 
    ;
    Oliveira, Rui
    ;
    Rivière, Etienne 
    Gossip-based protocols provide a simple, scalable, and robust way to disseminate messages in large-scale systems. In such protocols, messages are spread in an epidemic manner. Gossiping may take place between nodes using push, pull, or a combination. Push-based systems achieve reasonable latency and high resilience to failures but may impose an unnecessarily large redundancy and overhead on the system. At the other extreme, pull-based protocols impose a lower overhead on the network at the price of increased latencies. A few hybrid approaches have been proposed—typically pushing control messages and pulling data—to avoid the redundancy of high-volume content and single-source streams. Yet, to the best of our knowledge, no other system intermingles push and pull in a multiple-senders scenario, in such a way that data messages of one help in carrying control messages of the other and in adaptively adjusting its rate of operation, further reducing overall cost and improving both on delays and robustness. In this paper, we propose an efficient generic push-pull dissemination protocol, Pulp, which combines the best of both worlds. Pulp exploits the efficiency of push approaches, while limiting redundant messages and therefore imposing a low overhead, as pull protocols do. Pulp leverages the dissemination of multiple messages from diverse sources: by exploiting the push phase of messages to transmit information about other disseminations, Pulp enables an efficient pulling of other messages, which themselves help in turn with the dissemination of pending messages. We deployed Pulp on a cluster and on PlanetLab. Our results demonstrate that Pulp achieves an appealing trade-off between coverage, message redundancy, and propagation delay.
  • Publication
    Métadonnées seulement
    CoFeed: privacy-preserving Web search recommendation based on collaborative aggregation of interest feedback
    (2013-1-13)
    Felber, Pascal 
    ;
    Kropf, Peter 
    ;
    Leonini, Lorenzo
    ;
    Luu, Toan
    ;
    Rajman, Martin
    ;
    Rivière, Etienne 
    ;
    Schiavoni, Valerio 
    ;
    Valerio, José
    Search engines essentially rely on the structure of the graph of hyperlinks. Although accurate for the main trend, this is not effective when some query is ambiguous. Leveraging semantic information by the mean of interest matching allows proposing complementary results that are tailored to the user's expectations. This paper proposes a collaborative search companion system, CoFeed, that collects user search queries and that considers feedback to build user-centric and document-centric profiling information. Over time, the system constructs ranked collections of elements that maintain the required information diversity and enhance the user search experience by presenting additional results tailored to the user's interest space. This collaborative search companion requires a supporting architecture adapted to large user populations generating high request loads. To that end, it integrates mechanisms for ensuring scalability and load balancing of the service under varying loads and user interest distributions. Moreover, collecting the recommendation data poses the problem of users’ privacy, and the bias one peer can induce to the system by sending fake recommendations. To that end, CoFeed ensures both publisher anonymity and rate limitation. With the former, the origin of the data is never known by the server that processes it, even if several servers collude to spy on some user. The latter, combined with decoupled authentication, allows to minimize the influence of cheating peers sending fake recommendations. Experiments with a deployed prototype highlight the efficiency of the system by analyzing improvement in search relevance, computational cost, scalability and load balancing.
  • Publication
    Métadonnées seulement
    A Component-Based Middleware Platform for Reconfigurable Service-Oriented Architectures
    (2011-6-7)
    Seinturier, Lionel
    ;
    Merle, Philippe
    ;
    Rouvoy, Romain
    ;
    Romero, Daniel
    ;
    Schiavoni, Valerio 
    ;
    Stefani, Jean-Bernard