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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
    Métadonnées seulement
    A LRAAM-based Partial Order Function for Ontology Matching in the Context of Service Discovery
    (2017-6-14)
    Ludolph, Hendrik
    ;
    Babin, Gilbert
    ;
    Kropf, Peter 
    The demand for Software as a Service is heavily increasing in the era of Cloud. With this demand comes a proliferation of third-party service offerings to fulfill it. It thus becomes crucial for organizations to find and select the right services to be integrated into their existing tool landscapes. Ideally, this is done automatically and continuously. The objective is to always provide the best possible support to changing business needs. In this paper, we explore an artificial neural network implementation, an LRAAM, as the specific oracle to control the selection process. We implemented a proof of concept and conducted experiments to explore the validity of the approach. We show that our implementation of the LRAAM performs correctly under specific parameters. We also identify limitations in using LRAAM in this context.
  • Publication
    Métadonnées seulement
    Managing traffic in peer-to-peer networks: the token-web protocol
    (: Society for Modeling & Simulation International, 2011-1-22)
    Babin, Gilbert
    ;
    Kropf, Peter 
    ;
    Dormann, Silvia
    We distinguish two types of P2P protocols: structured protocols, which use a directed search approach, and unstructured protocols, which use a flooding approach. We propose the Token-Web as a new type of P2P, semi-structured protocols, that combines directed search and controlled flooding. The protocol presumes that most participants are trustworthy and therefore it does not require authentification. However, mechanisms to prevent disruption are set in place. In this paper, we describe the Token-Web and present results of experiments conducted to assess its properties in a simulated environment and on PlanetLab. The results obtained show that the number of tokens tends to stabilize over time, the message drop rate depends on the level of activity in the network, and the query success rate is dependent on the popularity of the resource sought.
  • Publication
    Métadonnées seulement
    Application-layer traffic analysis of a peer-to-peer system
    (2008)
    Tutsch, Dietmar
    ;
    Babin, Gilbert
    ;
    Kropf, Peter 
    Characterizing traffic behavior helps to optimize the network architecture for improved performance. Using a modified LimeWire servent ( for both the server and client) and a variance-time plot for traffic characterization, the authors analyze the Gnutella protocol's traffic shape and find that the messages exhibit a self-similar shape. This result shows network designers that they need to consider the self-similar traffic shape in their set-up - for instance, by introducing appropriate buffer sizes.
  • Publication
    Métadonnées seulement
    BALLS: a structured peer-to-peer system with integrated load balancing
    (2006-12-1)
    Le, Viet Dung
    ;
    Babin, Gilbert
    ;
    Kropf, Peter 
    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
    Métadonnées seulement
    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
    Métadonnées seulement
    A structured peer-to-peer system with integrated index and storage load balancing
    (: Springer Verlag, 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
    Métadonnées seulement
    Experimenting with gnutella communities
    (: Springer-Verlag Berlin, 2002)
    Vaucher, Jean
    ;
    Babin, Gilbert
    ;
    Kropf, Peter 
    ;
    Jouve, Thierry
    ;
    Plaice, John
    ;
    Kropf, Peter 
    ;
    Schulthess, Peter
    ;
    Slonim, Jacob
    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
    Métadonnées seulement
    SecAdvise: A security mechanism advisor
    (: Springer-Verlag Berlin, 2002)
    Saliba, Rima
    ;
    Babin, Gilbert
    ;
    Kropf, Peter 
    ;
    Plaice, John
    ;
    Kropf, Peter 
    ;
    Schulthess, Peter
    ;
    Slonim, Jacob
    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.
  • Publication
    Métadonnées seulement
    Optimisation of distributed communities using cooperative strategies
    (: Springer-Verlag Berlin, 2002)
    Yuen, Saiho
    ;
    Kropf, Peter 
    ;
    Babin, Gilbert
    ;
    Unger, Herwig
    ;
    Böhme, Thomas
    ;
    Mikler, Armin
    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
    Métadonnées seulement
    Resource warehouses: a distributed information management infrastructure
    (: SCS International, 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 approach is the use of a simple method to describe what is being 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.