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Kropf, Peter

Nom
Kropf, Peter
Affiliation principale
Fonction
Professeur.e ordinaire
Email
peter.kropf@unine.ch
Identifiants
https://libra.unine.ch/handle/123456789/221
_
0000-0001-6187-1510

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  • Publication
    Accès libre
    SoftwIre Integration - An Onto-Neural Perspective
    (: Springer, 2011-1-22)
    Ludolph, Hendrik
    ;
    Kropf, Peter 
    ;
    Babin, Gilbert
    We propose a framework for automated point-to-point application integration. Functional and technical aspects to consider are presented. We advocate using intelligible (ontological) and distributed (neural networks) knowledge representations to guide design and implementation of application interfaces. We believe this yields benefits over manual approaches currently used, in which business specifications are first captured, then translated into technical specifications, and finally implemented, often by costly third-party integration specialists. The present work initiates research efforts towards automation of the latter two activities, with a potential impact on professional-services costs and time-to-operation.
  • Publication
    Accès libre
    Application layer traffic analysis of a Peer-to-Peer system
    (2008)
    Tutsch, Dietmar
    ;
    Babin, Gilbert
    ;
    Kropf, Peter 
    Self-similar or multifractal behavior has been observed for LAN and Internet WAN (backbone) traffic. Investigations about this kind of behavior for application level protocols are rarely found because sessions or even applications are usually too short to be characterized in this direction. Only Telnet and FTP were examined so far. This paper analyzes the traffic shape of Peer-to-Peer (P2P) networks using the Gnutella protocol. Data was collected using a modified LimeWire servent. Self-similarity was estimated using a variance-time plot. The results show that Gnutella messages exhibit a self-similar shape, regardless of the message type.
  • Publication
    Accès libre
    BALLS Simulator : Evaluator of a structured Peer-to-Peer system with integrated load balancing
    (2006)
    Le, Viet-Dung
    ;
    Babin, Gilbert
    ;
    Kropf, Peter 
    Simulation is an efficient way to evaluate new peer-to-peer models. It requires two implicit properties: large scale and high dynamicity. In the context of our work that proposes a peer-to-peer structure based on partitioning a de Bruijn graph and its load balancing algorithms, we developed a simulator for evaluation purposes. This paper introduces a three- layer architecture of the simulator. This architecture allows to support simulations in two modes: centralized (where all peers are simulated on one physical machine) and decentralized (where the peers run on separate machines communicating through the underlying network).
  • Publication
    Accès libre
    BALLS: A structured Peer-to-Peer system with integrated load balancing
    (2006)
    Le, Viet-Dung
    ;
    Babin, Gilbert
    ;
    Kropf, Peter 
    L'équilibrage de charge est un problème majeur des systèmes pair-à-pair structurés. Nous nous intéressons plus particulièrement à l'utilisation de la bande passante pour le routage de messages et à l'utilisation des ressources informatiques pour le stockage d'objets. Dans cet article, nous présentons un réseau pair-à-pair structuré permettant l'équilibrage efficace et simultané de ces deux types de charge. Le réseau est construit en partitionnant les noeuds d'un graphe de De Bruijn et en assignant les partitions aux pairs. Les pairs équilibrent l'utilisation de la bande passante en repartitionnant les noeuds. On équilibre l'utilisation des ressources informatiques pour le stockage en dissociant l'emplacement d'un objet de celui de sa clé de recherche. L'article présente et analyse les protocoles requis pour main- tenir la structure de réseau et pour équilibrer la charge. Nous démontrons leur efficacité par simulation. Nous comparons également notre solution à d'autres approches., Load balancing is an important problem for structured peer-to-peer systems. We are particularly interested in the consumption of network bandwidth for routing traffic and in the usage of computer resources for object storage. In this paper, we investigate the possibility to simultaneously balance these two types of load. We present a structured peer-to-peer overlay that efficiently performs such simultaneous load balancing. The overlay is constructed by partitioning the nodes of a de Bruijn graph and by allocating the partitions to the peers. Peers balance network bandwidth consumption by repartitioning the nodes. Balancing of computer resources for storage is enabled by dissociating the actual storage location of an object from the location of its search key. The paper presents and analyzes the protocols required to maintain the overlay structure and perform load balancing. We demonstrate their efficiency by simulation. We also compare our proposed overlay network with other approaches.
  • Publication
    Accès libre
    A Structured Peer-to-Peer System with Integrated Index and Storage Load Balancing
    (2006)
    Le, Viet-Dung
    ;
    Babin, Gilbert
    ;
    Kropf, Peter 
    Load balancing emerges as an important problem that affects the performance of structured peer-to-peer systems. This paper presents a peer-to-peer system relying on the partitionning of a de Bruijn graph. The proposed system integrates mechanisms that perform index and storage load balancing. Index load refers to the network traffic incurred by a peer in managing an object index, while storage load refers to the storage space and network traffic required to store objects. The proposed mechanisms allow to effectively distribute both index load and storage load according to the peers’ capacities.
  • Publication
    Accès libre
    A Communication Framework Towards Flexible Associations of Business entities within Evolving environments
    (2003)
    Le, Viet-Dung
    ;
    Babin, Gilbert
    ;
    Kropf, Peter 
    The Internet and its manifestations, such as electronic commerce or in general network communication between different group sof interest (i.e., agents) have become indispensable for many of us. To adequately use the ever increasing amount of data, attempts are being made to extend data processing from a merely lexical view towards more complex, but equally important, multi-level view, including meaning and/or context (e.g., DAML, Web Services). The goal of this paper is to introduce a formal framework, apt to model communications from such a multi-level perspective. Therein, we discuss fundamental ideas of communication, such as agents involved and their respective structure. We integrate the concept of an agent’s adaptive behaviour in order to assure a high degree of understanding. The framework is then illustrated using practical examples where we briefly present its usefulness and how it may be further developed.
  • Publication
    Accès libre
    Resource Warehouses; a Distributed Information Warehouse Infrastructure
    (2002)
    Khoury, Simon
    ;
    Kropf, Peter 
    ;
    Babin, Gilbert
    This paper presents work related to the design of distributed systems, which is useful for emerging Internet applications. We propose algorithms for searching and managing distributed information about resources and services using locally available warehouses. The concept of warehouses has been introduced in the Web Operating System (WOS) (Kropf 1999). Warehouses have the ability to decide which information should be stored, replaced or removed without any intervention of the user. We present a tree structure for WOS warehouses, an attribute/value scheme used for describing resources, and the algorithms to look up information about resources. Among other things, warehouses take into account the capacity limitations of the devices that the WOS is using. Moreover, in order to share locally available information, WOS warehouses need to communicate with each other. We present an approach which allows for profitable exchange of information between the various warehouses. The advantage of our ap- proach is the use of a simple method to describe what is be- ing looked for (i.e., the intent), instead of specifying where to find it (i.e., the extent). We have implemented our warehouse structure in Java taking advantage of its portability.
  • Publication
    Accès libre
    Optimisation of Distributed Communities Using Cooperative Strategies
    (2002)
    Yuen, Saiho
    ;
    Kropf, Peter 
    ;
    Babin, Gilbert
    The complex structure of the Web requires decentralised, adaptive mechanisms efficiently providing access to local and global capacities. To facilitate the development of such mechanisms, it seems reasonable to build clusters of machines with similar structures and interests. In such a manner, communities of machines can be built. In a community, every machine contributes to the overall success through a division of management work and a respective collaboration. This article presents and analyses experimental results for algorithms optimising service response times in a community. It extends previously published results on the Wanderer optimisation algorithm; we describe variations of the Wanderer and present simulation results of these variations.
  • Publication
    Accès libre
    Experimenting with Gnutella Communities
    (2002)
    Vaucher, Jean
    ;
    Babin, Gilbert
    ;
    Kropf, Peter 
    ;
    Jouve, Thierry
    Computer networks or distributed systems in general may be regarded as communities where the individual components, be they entire systems, application software or users, interact in a shared environment. Such communities dynamically evolve with components or nodes joining and leaving the system. Their own individual activities affect the community’s behavior and vice versa. This paper discusses various practical experiments undertaken to investigate the behavior of a real system, the Gnutella network, which represents such a community. Gnutella is a distributed Peer-to-Peer data-sharing system without any central control. It turns out that most interactions between nodes do not last long and much of their activity is devoted to finding appropriate partners in the network. The experimental results presented have been obtained from a Java implementation of Gnutella running in the open Internet environment, and thus in unknown and quickly changing network structures heavily depending on chance.
  • Publication
    Accès libre
    SecAdvise: A Security Mechanism Advisor
    (2002)
    Saliba, Rima
    ;
    Babin, Gilbert
    ;
    Kropf, Peter 
    The proliferation of incompatible e-commerce systems applying different security technologies imposes difficult choices on all the concerned parties. In this context, the purpose of this research is to provide the necessary background to develop a security advisor (SecAdvise), which will make it possible to integrate the security mechanisms and the dynamic selection of the various mechanisms between several parties wishing to conduct business transactions safely. Such an advisor aims multiple goals: overcoming compatibility and interoperability problems, evaluating and reducing technological security risks, and enhancing trust.