Data sharing in DHT based P2P systems

International audienceThe evolution of peer-to-peer (P2P) systems triggered the building of large scale distributed applications. The main application domain is data sharing across a very large number of highly autonomous participants. Building such data sharing systems is particularly challenging because of the "extreme" characteristics of P2P infrastructures: massive distribution, high churn rate, no global control, potentially untrusted participants... This article focuses on declarative querying support, query optimization and data privacy on a major class of P2P systems, that based on Distributed Hash Table (P2P DHT). The usual approaches and the algorithms used by classic distributed systems and databases forproviding data privacy and querying services are not well suited to P2P DHT systems. A considerable amount of work was required to adapt them for the new challenges such systems present. This paper describes the most important solutions found. It also identies important future research trends in data management in P2P DHT systems

IOPE: Interactive Ontology Population and Enrichment Guided by Ontological Constraints (revised version from WISE'21)

International audienceIn this paper, we focus on the construction of specialized ontologies that capture skills of experienced experts in a particular domain with the goal to share them with a larger community of trainees or less experienced experts in the domain. Our main contribution is the automatic construction of a Graphical User Interface (GUI), named IOPE, built from the ontological constraints of an input ontology, as the support of the controlled update process of the considered ontology. The resulting GUI functions as a guidance for the experts with no knowledge of OWL/RDFS, which enables them to easily explore and update their ontologies. We illustrate the functionality of IOPE on an ontology for simulation-based medical workshops called ONTOSAMSEI. In an extensive set of experiments, we discuss the effectiveness and efficiency of our proposed approach in a specialized medical domain.Dans cet article, nous abordons la construction d'ontologies métiers qui capturent les compétences de spécialistes experts du domaine, et cela dans un but de partage avec une communauté d'apprenants et de spécialistes moins expérimentés.Notre principale contribution est la construction automatique d'une interface utilisateur, nommée IOPE, à partir des contraintes d'une ontologie métier, et autorisant la mise à jour et l'enrichissement contrôlée de cette ontologie. L'interface graphique joue le rôle de guide pour les experts qui n'ont aucune connaissance des langages ontologiques (OWL/RDFS). Nous illustrons l'usage d'IOPE à l'aide d'une ontologie spécialisée dans le domaine des ateliers médicaux pour la simulation, appelée ONTOSAMSEI

Towards a Mediation System Framework for Transparent Access to Largely Distributed Sources

International audienc