Members
Heads
Hala Skaf-Molli, Professor at Nantes Université, Head of GDD
Patricia Serrano-Alvarado, Associate Professor (HDR) at Nantes Université. Vice-Head of GDD
Members
Pascal Molli, Full Professor at Nantes Université since September 2010.
Achour Mostéfaoui, Full Professor at Nantes Université since November 2011
Matthieu Perrin, Associate Professor at Nantes Université, since September 2017
External Collaborator
Alban Gaignard, CNRS engineer, Institut du thorax, Inserm UMR 1087 / CNRS UMR 6291
Ph.D. Students
Julien Aimonier-Davat, Started in September 2020, Advisor: Hala Skaf-Molli, Co-Advisor: Pascal Molli
Vincent Kowalski. Started in October 2021. Advisor Achour Mostéfaoui, Co-Advisor: Emmanuelle Anceaume.
Minh-Hoang DANG. Started in October 2021. Advisor Pascal Molli, co-Advisor: Hala Skaf-Molli
Ghinwa Fakih. Started in January 2022. Advisor Patricia-serrano-alvarado
Manoé kieffer. Started in Septembre 2022. Advisor Patricia-serrano-alvarado
Hoang Thi Pham Thi, started in September 2023, Advisor Pascal Molli, co-Advisor: Hala Skaf-Molli
Engineer
Brice Nédelec. Started in January 2022
MsC Students
Manoé Kieffer, MsC. thesis Started in Februay 2022, Advisor: Patricia Serrano-Alverado
Former members
2022
Emmanuel Desmontils, associated professor at Nantes Université
2021
Swann Espagne, MsC. thesis, Started in January 2021, Advisor: Pascal Molli, Hala Skaf-Molli
François Lépine, MsC. thesis Started in January 2021, Advisor: Hala Skaf-Molli, Pascal Molli
Grégoire Bonin, thesis Started in September 2017, Advisor: Achour Mostefaoui, Co-Advisor: Matthieu Perrin
2020
Benjamin Moreau, Started in October 2017, Advisor: Pascal Molli, Co-Advisors: Patricia Serrano & Emmanuel Desmontils
CIFRE thesis in collaboration with OpenDataSoft
Facilitating Reuse On The Web Of Data
Defended November 6th, 2020
Abstract: Le Web des données est un ensemble de données liées qui peuvent être interrogées et réutilisées à l'aide de moteurs de requêtes fédérées. Pour protéger les jeux de données, les licences renseignent leurs conditions d'utilisation. Cependant, choisir une licence conforme n'est pas toujours aisé. En effet, pour protéger la réutilisation de plusieurs jeux de données, il est nécessaire de prendre en considération la compatibilité entre leurs licences. Nous pensons que pour faciliter la réutilisation, les moteurs de requêtes fédérées devraient respecter les licences. Dans ce contexte, nous nous intéressons à deux problèmes (1) comment calculer la relation de compatibilité entre des licences, et (2) comment respecter les licences pendant le traitement de requêtes fédérées. Pour le premier problème, nous proposons CaLi, un modèle capable d'ordonner partiellement n'importe quel ensemble de licences selon leur compatibilité.Pour le second problème, nous proposons FLiQue, un moteur de requête fédéré respectant les licences. FLiQue utilise CaLi pour détecter les conflits de compatibilité entre licences et assure que le résultat d'une requête fédérée respecte les licences. Dans le cadre de cette thèse, nous proposons également trois approches ODMTP, EvaMap et le SemanticBot ayant pour objectif de faciliter l'intégration de données au web des données.
Thomas Minier, Started in September 2017. Advisor: Pascal Molli, Co-Advisor: Hala Skaf
Web Preemption for Querying the Linked Open Data
Defended November 10th, 2020 / Youtube Replay of the Defense / Slides
Abstract: Following the Linked Open Data principles, data providers have published billions of RDF documents using public SPARQL query services. To ensure these services remain stable and responsive, they enforce quotas on server usage. Queries that exceed these quotas are interrupted and deliver partial results. Such interruption is not an issue if it is possible to resume queries execution afterward. Unfortunately, there is no preemption model for the Web that allows for suspending and resuming SPARQL queries. In this thesis, we propose to tackle the issue of building public SPARQL query servers that allow any data consumer to execute any SPARQL query with complete results. First, we propose a new query execution model called Web Preemption. It allows SPARQL queries to be suspended by the Web server after a fixed time quantum and resumed upon client request. Web preemption is tractable only if its cost in time is negligible compared to the time quantum. Thus, we propose SaGe: a SPARQL query engine that implements Web Preemption with minimal overhead. Experimental results demonstrate that SaGe outperforms existing SPARQL query processing approaches by several orders of magnitude in terms of the average total query execution time and the time for first results.
Arnaud Grall, Started in October 2017. Advisor: Pascal Molli, Co-Advisor: Hala Skaf
CIFRE thesis in collaboration with GFI World
Defended on December 15th, 2020
2018
Maxime Folschette, PostDoc
Started 2018, ended 2020, working in the national project INEX-MED , using the semantic web for data integration of Health data.
Maxime is now associate professor at Centrale Lille Institut
Brice Nédelec, PostDoc
Started in May 2017, ended in December 2018
Sara El Hassad, PostDoc
Started in March 2018, ended in March 2019
Nourredine Haouri, Research Engineer
Started in February 2018, ended in December 2018
Now: Research Engineer at WIDE (IRISA, Université Rennes 1)
2017
Matoula Petrolia, Started in December 2013. Advisor: Achour Mostefaoui, Co-Advisor: Claude Jard
Pauline Folz, Started in February 2014. Advisor: Pascal Molli, Co-Advisor: Hala Skaf.
Now: Researcher at Orange Labs (Grenoble) since June 2018
Defended 12 octobre 2017
Abstract : Following the Linked Data principles, data providers have published billions of RDF facts on the web. Anyone can retrieve some relevant information from the Linked Data by executing SPARQL queries. Such queries are useful in many domains including health or data journalism. However, there is a trade-off between performances of the queries and data availability when executing SPARQL queries. In this thesis, we have investigated how the collaboration of data consumers is opening new opportunities in this trade-off. More precisely, how the collaboration of data consumers can improve performances without degrading availability, or can improve availability without degrading performances. We consider that Linked Data can allow anyone to run a compact mediator that executes SPARQL queries over data sources on the web. The main idea is to connect these mediators together to build a federation of Linked Data consumers. In this federation, each mediator interacts with a subset of the network. Thanks to this federation, we have built : (i) a decentralized cache hosted by mediators. This client-side cache is able to handle a significative part of subqueries and then improve data availability without a low impact on performances. (ii) a delegation algorithm that allows mediators to delegate their queries to other mediators. We have demonstrated that delegation allows to run the workloads faster when collaborating. This clearly improves performances without degrading data availability.
Yann Busnel, Associate Professor at University of Nantes. (Now PR@IMT since September 2016)
Georges Nassopoulos, Started in October 2013. Advisor: Pascal Molli, Co-Advisor: Patricia Serrano, Emmanuel Desmontils
Deducing Basic Graph Patterns from Logs of Linked Data Providers, defended, May, 22, 2017
Abstract : Following the principles of Linked Data, data providers published billions of facts as RDF data. Executing SPARQL queries over SPARQL endpoints or Triple Pattern Fragments (TPF) servers allow to easily consume Linked Data. However, federated SPARQL query processing and TPF query processing decompose the initialquery into subqueries. Consequently, the data providers only see subqueries and the initial query is only known by end users. Knowing executed SPARQL queries is fundamental for data providers, to ensure usage control, to optimize costs of query answering, to justify return of investment, to improve the user experience or to create business models of usage trends. In this thesis, we focus on analyzing execution logs of TPF servers and SPARQL endpoints to extract Basic Graph Patterns (BGP) of executed SPARQL queries. The main challenge to extract BGPs is the concurrent execution of SPARQL queries. We propose two algorithms: LIFT and FETA. LIFT extracts BGPs of executed queries from a single TPF server log. FETA extracts BGPs of federated queries from a log of a set of SPARQL endpoints. For experiments, we run LIFT and FETA on synthetic logs and real logs. LIFT and FETA are able to extract BGPs with good precision and recall under certain conditions.
2016
Brice Nédelec, Started in September 2012, Advisor: Pascal Molli, Co-Advisor: Achour Mostefaoui
"Collaborative editing in browsers", defended 5 october 2016
Abstract: Collaborative editors allow users to distribute the writ- ing of a document across space and time. Thanks to their ease of use, real-time collaborative editors working in Web browsers vastly contributed to the adoption of such tools. However, current editors are centralized : a service provider’s server hosts an editing session. It raises privacy and scalability issues. Recently, the enabling of browser-to-browser connection establishments opened new opportunities in favor of a de- centralized Web. Decentralized real-time collaborative editors working in Web browsers must effciently handle highly dynamic groups of different size. Contributions of this thesis are threefold : (i) To represent the document, we propose a replicated data structure for sequences using metadata the size of which scales sub- linearly compared to the number of inserted characters. (ii) To effciently propagate the changes to all editors involved in the collaborative writing, we propose a random peer sampling protocol that supports Web browsers constraints and self-adjusts its functioning to the variations of network membership. (iii) To demonstrate the feasibility of a decentralized real-time collaborative editors running in Web browsers, we propose an editor using (i) and (ii), and we highlight its scalability.
Nicolo Rivetti, Started in November 2013. Advisor: Achour Mostefaoui, Co-Advisor: Yann Busnel
"Efficient Stream Analysis and its Application to Big Data Processing", defended: 30 septembre 2016
abstract: Nowadays stream analysis is used in many context where the amount of data and/or the rate at which it is generated rules out other approaches (e.g., batch processing). The data streaming model provides randomized and/or approximated solutions to compute specific functions over (distributed) stream(s) of data-items in worst case scenarios, while striving for small resources usage. In particular, we look into two classical and related data streaming problems: frequency estimation and (distributed) heavy hitters. A less common field of application is stream processing which is somehow complementary and more practical, providing efficient and highly scalable frameworks to perform soft real-time generic computation on streams, relying on cloud computing. This duality allows us to apply data streaming solutions to optimize stream processing systems. In this thesis, we provide a novel algorithm to track heavy hitters in distributed streams and two extensions of a well-known algorithm to estimate the frequencies of data items. We also tackle two related problems and their solution: provide even partitioning of the item universe based on their weights and provide an estimation of the values carried by the items of the stream. We then apply these results to both network monitoring and stream processing. In particular, we leverage these solutions to perform load shedding as well as to load balance parallelized operators in stream processing systems.
Gabriela Montoya, Started in October 2012. Advisor: Pascal Molli, Co-Advisor: Hala Skaf.
Now: Associate Professor at Aalborg University
"Answering SPARQL Queries using Views", defended 11 March 2016.
Abstract: The Semantic Web allows data publishers to make available an increasing number of datasets concerning the whole society. SPARQL queries can be written to consume the datasets data. In this context, the effective execution of SPARQL queries on the relevant datasets is a critical issue. Unfortunately, SPARQL does not allow to access data from the Deep Web, and this significantly reduces the search space. In addition, the existing infrastructures to execute the SPARQL queries do not provide good data availability. To address these two problems, we have used views in the Semantic Web context to optimize the query execution and also the access to the Deep Web. SemLAV is a mediator that allows for executing SPARQL queries over data sources on the Web. SemLAV is based on views that relate external data to the mediator global schema. SemLAV avoids generating and executing an exponential number of query rewritings by computing the materialization order for the selected views. FEDRA considers a federation of SPARQL endpoints that have partially replicated datasets. FEDRA optimizes the execution of federated queries by selecting the endpoints in a way that the transferred data are minimized.
Matthieu Perrin, Started in October 2012. Advisor: Claude Jard (AELOS), Co-Advisor: Achour Mostefaoui.
"Spécification des objets partagés dans les systèmes répartis sans-attente", defended 7 june 2016
Dans les systèmes répartis à très large échelle, les critères de cohérence forts comme la cohérence séquentielle et la linéarisabilité sont souvent trop coûteux, voire impossibles à obtenir. Dans cette thèse, nous nous posons la question de la spécification des objets que l’on peut tout de même obtenir. Nous soutenons qu’il est toujours possible de séparer leur spécification en deux facettes : un type de données abstrait qui spécifie l’aspect fonctionnel des opérations et un critère de cohérence faible qui décrit la qualité de service garantie par l’objet dans son environnement réparti. Nous illustrons ces concepts par une mise en œuvre dans le langage D : les types de données abstraits sont les classes du programme et les critères de cohérence sont choisis dans une liste fournie par la bibliothèque CODS. Nous dressons une carte de l’espace des critères faibles organisée autour de trois familles de critères primaires (localité d’état, convergence et validité) et trois familles de critères secondaires (cohérence d’écritures, cohérence pipeline et sérialisabilité). Chaque critère secondaire renforce deux critères primaires, mais les trois critères primaires ne peuvent pas être implémentés ensembles dans les systèmes considérés. Nous étudions également l’effet de la causalité sur ces familles.
2015
Luis-Daniel Ibáñez, Started in August 2011. Advisor: Pascal Molli, Co-Advisors: Hala Skaf-Molli, Olivier Corby
Now: Lecturer at University of Southampton, WAIS Team (UK)
"Towards a Read/Write Web of Linked Data", defended 25 feb 2015.
Abstract : The Linked Data initiative has made available millions of pieces of data for querying through a federation of autonomous participants. However, the Web of Linked data suffers of problems of data heterogeneity and quality. We cast the problem of integrating heterogeneous data sources as a Local-as-View mediation (LAV) problem, unfortunately, LAV may require the execution of a number of “rewritings” exponential on the number of query subgoals. We propose the Graph-Union (GUN) strategy to maximise the results obtained from a subset of rewritings. Compared to traditional rewriting execution strategies, GUN improves execution time and number of results obtained in exchange of higher memory consumption. Once data can be queried data consumers can detect quality issues, but to resolve them they need to write on the data of the sources, i.e., to evolve Linked Data from Read/Only to Read-Write. However, writing among autonomous participants raises consistency issues. We model the Read-Write Linked Data as a social network where actors copy the data they are interested into, update it and publish updates to exchange with others. We propose two algorithms for update exchange: SU-Set, that achieves Strong Eventual Consistency (SEC) and Col-Graph, that achieves Fragment Consistency, stronger than SEC. We analyze the worst and best case complexities of both algorithms and estimate experimentally the average complexity of Col-Graph, results suggest that is feasible for social network topologies.
2014
Diego Torres, Started in December 2010. Advisor: Pascal Molli, Co-Advisor: Alicia Diaz, Hala Skaf-Molli
Defense on 3 october 2014
Title:"Personal Knowledge Management in the context of Web Knowledge Communities''
Abstract : Social and Semantic Web has impacted in the manner of knowledge building is fulfill in the Web. The Social Web promoted the partici- pation of users to create and edit Web content and knowledge. The content proliferation and the need to have a better machine mana- gement of such information trigger the Semantic Web. Currently, the Social and the Semantic Web are living together and they share a same topic: a better management of knowledge. However, most of the Social Web information is not part of the Semantic Web, and Semantic Web information is not used to improve the Social Web. This thesis introduced an innovative approach to stimulate a co- evolu- tion between the Semantic and Social Web: social and machine forces work together in order to have mutual benefits. We claim that having a co-evolution between Social and Semantic Web will improve the ge- neration of semantic data and a knowledge production improvement in the Social Web.
Nagham Alhadad, Started in September 2010. Advisor: Philippe Lamarre, Co-Advisors: Yann Busnel, Patricia Serrano-Alvarado.
Title: "Combler le fossé entre les mondes sociaux et numériques : modélisation de systèmes et évaluation de la confiance", 20 June 2014
Jury: Bruno DEFUDE, Professeur d’université, TELECOM SudParis, rapporteur. Marie-Christine ROUSSET, Professeur d’université, Université Joseph Fourier de Grenoble, rapportrice. Emmanuelle ANCEAUME, Chargée de Recherche, IRISA / CNRS Rennes, examinatrice. Pascal MOLLI, Professeur d’université, Université de Nantes, examinateur. Christophe SIBERTIN-BLANC, Professeur d’université, Université Toulouse1–Capitole, examinateur. Yann BUSNEL, Maître de conférence, Université de Nantes, co-encadrant. Philippe LAMARRE, Professeur d’Université, INSA de Lyon, directeur. Patricia SERRANO-ALVARADO, Maître de conférence, Université de Nantes, co-encadrante
Abstract: Nowadays, digital systems are connected through complex architectures. Participants to these systems perform activities like chatting or sharing data. Persons, physical and digital resources are involved in these activities, such that a system can be considered as a representation of two worlds, the social world and the digital world and their relations. Evaluating these systems is generally limited to technical aspects. Today, trust becomes an important key in the evaluation process. In this context, we raise two questions: how to formalize the entities that compose a system and their relations for a particular activity? and how to evaluate trust in a system for this activity? Our contributions are divided into two parts. The first part proposes a formal metamodel named SocioPath, to model a system with all entities of social and digital worlds and their relations. The second part evaluates the users’ trust in the systems they use for a given activity. We propose an approach named, SocioTrust, to compute the user’s trust in a system using probability theory. Then we propose a second approach named, SubjectiveTrust that takes into account the uncertainty in the trust values. This approach is based on subjective logic.
2012
Sylvie Cazalens, Associate Professor at University of Nantes until 2012, now associate professor in Lyon.
Toufik Sarni, Started in 2009. Advisor: Patrick Valduriez, Co-advisor: Audrey Queudet.
Title: "Vers une mémoire transactionnelle temps réel" ("Towards a real-time transactional memory"), 16 October 2012.
Jury: Michel Banâtre, Directeur de Recherche INRIA Rennes (rapporteur), Luc Bouganim, Directeur de Recherche INRIA Paris-Rocquencourt (rapporteur), Maryline Chetto, Professeur Université de Nantes (examinatrice), Audrey Queudet, Maître de conférences Université de Nantes (co-encadrante), Gaël Thomas, Maître de Conférences Université Pierre et Marie Curie (examinateur), Patrick Valduriez, Directeur de Recherche INRIA Montpellier (directeur)
Abstract : With the advent of multicore systems, the transactional memory (TM) concept has attracted much interest from both academy and industry. Indeed, by supporting the ACI (Atomicity, Consistency and Isolation) proprieties, the TM concept eases parallel programming and avoids the severe problems of lock-based methods such as deadlock situations and priority inversion. In addition, unlike lock-based methods, TM allows several transactions to access resources in parallel, and thus increases the system's bandwidth. Moreover, TM embeds a transaction's scheduler which either rollbacks the transaction when the conflict is detected, or commits the transaction on success. The thesis's objective is to study the TM's adaptation to soft real-time systems in which processes must complete within deadlines as far as it is possible. Up to now, the scheduling of real-time transactions within TM has not been studied. To address this issue, we first make an experimental and comparative study to show whether the TM is suitable for real-time multicore systems. In particular, we evaluate the transaction's execution time variation when accessing shared resources. Second, we propose a novel solution which introduces a real-time transactional model within TM and we design and implement a real-time software transactional memory named RT-STM. This one integrates new synchronization protocols which allows to prioritize the shared resources' accesses according to the processes' urgency. Finally, we show how to make RT-STM suitable for firm real-time systems, proposing some adaptations allowing to guarantee a certain level of quality of service (QoS) to processes sharing resources.
Thomas Cerqueus, Started in October 2009. Advisor: Philippe Lamarre, Co-Advisors: Sylvie Cazalens
Title : Contributions au problème d'hétérogénéité sémantique dans les systèmes pair-à-pair : application à la recherche d'information, 15 November 2012.
Jury : Sylvie Calabretto, Professeur Université de Lyon (rapporteur), Abdelkader Hameurlain, Professeur Université de Toulouse (rapporteur), Gabriel Antoniu, Directeur de recherche INRIA Rennes (examinateur), Marc Gelgon, Professeur Université de Nantes (examinateur), Sylvie Cazalens, Maître de conférence Université de Nantes (co-encadrante), Philippe Lamarre, Professeur Université de Lyon (directeur)
Abstract : We consider peer-to-peer (P2P) data sharing systems in which each peer is free to choose the ontology that best fit its needs to represent its data. This is what we call semantic heterogeneity. This situation prevents from perfect interoperability because queries issued by peers may be misunderstood by other peers. First we focus on the notion of semantic heterogeneity because it seems to us that it is a complex notion. We define several measures allowing to precisely characterize semantic heterogeneity of a P2P system according to different facets. Second we define two protocols. The first one, called CorDis, allows to reduce semantic heterogeneity related to the disparities between peers. It disseminates correspondences in the system so that peers learn new correspondences. The second protocol, called GoOD-TA, allows to reduce semantic heterogeneity related to the topology of a system. The goal is to organize it in way that semantically close peers are close in the system. Thus two peers are neighbours if they use the same ontology, or if numerous correspondences exist between their respective ontologies. Third we propose an algorithm called DiQuESH for the routing and the treatment of top-k queries in semantically heterogeneous P2P systems. This algorithm allows a peer to retrieve the k most relevant documents from its neighbourhood. We experimentally show that CorDis and GoOD-TA improve results obtained by DiQuESH.
Khaled Aslan Almoubayed, Started in November 2009. Advisor: Pascal Molli, Co-Advisor: Hala Skaf-Molli
Title: "Divergence Awareness in Distributed Multi-Synchronous Collaborative Systems'', 26 November 2012.
Jury : Bruno Defude, Professeur, TELECOM SudParis (rapporteur), Nicolas Roussel, Directeur de Recherche, INRIA Lille (rapporteur), Marc Gelgon, Professeur, Université de Nantes (examinateur), Gérald Oster, Maître de Conférences, Université de Lorraine (examinateur), Pascal Molli, Professeur, Université de Nantes (directeur de thèse), Hala Skaf-Molli, Maître de Conférences, Université de Nantes (co-encadrante de thèse).
Abstract : Multi-synchronous collaborative systems support parallel streams of activities on replicated data. They allow streams of activities to diverge. If divergence can help to reduce completion time, it can also generate important overhead when solving conflicts. Divergence awareness is one approach that aims to limit conflicts by making users aware of divergence. It aims to answer the following questions: is there any divergence? With whom? Where? And how much? Existing divergence awareness metrics are highly coupled to their original applications and can not be used outside their original scope. In addition, existing divergence awareness do not estimate a global state of the system with all its workspace in a fully distributed way. In this thesis, I propose a formal model to express existing divergence awareness metrics. I propose also an original group divergence metric that addresses specifically the "how much?" question. This metric makes users aware of the distance of the group to the next potential convergence point. I define formally the group divergence awareness metric. Next, I propose an algorithm to compute group divergence metric on logs and validates the algorithm with real data from different development projects. Finally, I propose an original approach based on overlay network to compute group divergence metric in real-time in a fully decentralized network and validate the approach with simulations. Key Words Multi-synchronous Collaboration, Divergence Awareness, Distributed System, Semantic Web.
William Kokou Dedzoe [Fellowship CNRS], Engineer in Labex CominLabs. Thesis in 2012
Title: Traitement de Requêtes Top-k dans les Communautés Virtuelles P2P de Partage de Données
Abstract : Top-k queries have two main advantages for peer-to-peer (P2P) data sharing virtual communities. First, they allow participants to rank the results for their queries based on the existing data in the system as well as on their own preferences. Second, they avoid overwhelming participants with too many results. However, existing top-k query processing techniques for P2P systems make users su er from long waiting times. This becomes even more problematic in overloaded P2P systems. In this thesis, we revisit the top-k query processing problem and introduce two new measures: the stabilization time and the cumulative quality gap. These two novel measures, in addition to existing measures, allow for better evaluating the behavior of top-k query processing techniques. We then propose a new family of top-k query processing techniques (ASAP) that allows to return high quality results as soon as possible. Finally, we study the problem of top-k query processing in overloaded systems. As a result, we propose a new approach, called QUAT, that relies on synthetic data descriptions of peers in order to allow peers to prioritize queries for which they can provide high quality results.
Raziel Carvajal-Gómez, Ingénieur de Recherche (2011-2012)
Gerson Sunyé, Associate Professor at University of Nantes. (end in 2012)
Audrey Queudet. Ass. Professor (end in 2012)
Marco Biazzini. (post doc in 2011-2012)
2011
Philippe Lamarre, Ass. Prof. Personal page (end in 2011)
Mounir Tlili [Fellowship Miles] (thesis in 2011)
title: "P2P Infrastructure for Data Replication and Reconciliation"
Abstract : In this thesis, we address the problem of optimistic replication for collaborative text editing in Peer-to-Peer (P2P) systems. This problem is challenging because of concurrent updating at multiple peers and dynamic behavior of peers. Operational transformation (OT) is a typical approach used for handling optimistic replication in the context of distributed text editing. However, most of OT solutions are neither scalable nor suited for P2P networks due to the dynamic behavior of peers. In this thesis, we propose a scalable P2P reconciliation infrastructure for OT that assures eventual consistency and liveness despite dynamicity and failures. We propose a P2P logging and timestamping service, called P2P-LTR (P2P Logging and Timestamping for Reconciliation) that exploits a distributed hash table (DHT) for reconciliation. While updating replica copies at collaborating peer editors, updates are stored in a highly available P2P log. To enforce eventual consistency, these updates must be retrieved in a specific total order to be reconciled at the peer editors. P2P-LTR provides an efficient mechanism for determining the total order of updates. It also deals with the case of peers that may join and leave the system during update operations. We evaluated the performance of P2P-LTR through simulation; the results show the efficiency and the scalability of our solution.
Mohamed Jawad, Phd of University of Nantes (Defense 29 June 2011), Ater since September 2011
Title: "Data Privacy in P2P Systems"
Jury; Président : Esther PACITTI Université de Montpellier Rapporteurs : Philippe PUCHERAL, Professeur Université de Versailles St-Quentin, Claudia RONCANCIO, Professeur Institut Polytechnique de Grenoble Examinateurs : Esther PACITTI, Professeur Université de Montpellier, Patrick VALDURIEZ, Directeur de Recherche INRIA, Patricia SERRANO-ALVARADO, Maître de Conférences Université de Nantes
2010 and before
Anthony VENTRESQUE. PhD student, then Ater. (leaved in 2010)
Trung Vu Duc [Fellowship INRIA - Région Pays de la Loire]
Patrick Valduriez, Dr INRIA, Zenith Team, LIRMM, Montpellier
Jean Bézivin, Prof., Nantes University.
Esther Pacitti, Prof., Zenith Team, LIRMM, Montpellier
Reza Akbarinia, CR INRIA, Zenith Team, LIRMM, Montpellier
Jorge Quiané Ruiz
Rabab Hayek.
Jorge Manjarrez Sanchez.
Wenceslao Palma.
Manal El Dick.