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Auflistung P061 - KiVS 2005 - Kommunikation in verteilten Systemen nach Erscheinungsdatum
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- KonferenzbeitragFederated Identity Management: Die Notwendigkeit zentraler Koordinationsdienste(Kommunikation in Verteilten Systemen (KiVS), 2005) Hommel, Wolfgang; Reiser, HelmutIdentity & Access Management (I&AM) Systeme bilden eine moderne Basis f ür die organisationsinterne Verwaltung von Mitarbeitern und Kunden sowie deren Zugriff auf lokale Ressourcen. Ihr Wirkungsbereich endet allerdings an den Organisationsgrenzen. Im Rahmen von B2B-Szenarien, beispielsweise beim Supply Chain Management, wächst jedoch der Bedarf, auch die Accounts und Rechte der Mitarbeiter und Kunden von Partnerunternehmen effizient verwalten zu können, d.h. diese Organisationsgrenzen zu überschreiten. Die zentrale Idee des Federated Identity Managements (FIM) ist, die Partnerunternehmen als autoritative Quelle für die Identitätsinformationen zu nutzen und die damit zusammenhängenden Management-Aufgaben an diese zu delegieren. In diesem Artikel zeigen wir, dass die drei derzeit fortgeschrittensten FIM-Ansätze – SAML, Liberty Alliance und WS-Federation – mehrere methodische und funktionale Defizite aufweisen, die einen effizienten Aufbau von FIM-Szenarien in der Praxis erschweren. Als Lösung eines Teils dieser Probleme stellen wir einen zentralen Koordinationsdienst für Identitätsföderationen vor, der im Rahmen unserer Forschung prototypisch implementiert wird.
- KonferenzbeitragCombining service-orientation and peer-to-peer networks(Kommunikation in Verteilten Systemen (KiVS), 2005) Conrad, Michael; Dinger, Jochen; Hartenstein, Hannes; Schöller, Markus; Zitterbart, MartinaAlmost all current P2P applications are built as monolithic systems: they tightly couple application software with an underlying P2P technology. For simple P2P applications like file sharing of instant messaging this does not represent a deficiency. For more general scenarios, e.g., for providing an electronic market place based on P2P technology, flexibility has to be increased. We propose to decouple the application from its underlying P2P network and introduce a mechanism that allows us to dynamically bind an overlay from a given set to a specific application. This paper describes the design of such a system's architecture that combines the service-oriented architecture paradigm and P2P technology. Using these two different technologies in an integrated way gives us flexibility to bind the best fitting P2P network to the executed service. In addition, it allows us to easily add and deploy new services.
- KonferenzbeitragOverlay-Verwaltung ist Datenverwaltung(Kommunikation in Verteilten Systemen (KiVS), 2005) Behnel, StefanDie Erstellung von Software zur Verwaltung von Overlay-Netzwerken ist aufwändig. Dies steht im Widerspruch zu der hohen Ähnlichkeit zwischen bestehenden Systemen. Sie alle müssen Nachrichten verabeiten und die jeweilige Topologie verwalten. Es stellt sich daher die Frage nach Middleware-Unterstützung, um durch vereinfachte Modelle die Entwicklungsarbeit zu erleichtern. Der vorgestellte Ansatz, genannt “Knotensichten”, modelliert die Verwaltung von Overlay-Netzwerken aus der Sicht der Datenverwaltung. Er verwendet Datenbanksichten und Ereignis-basierte Interaktion um die Aufteilung von Overlay-Software in generische, wiederverwendbare Komponenten zu ermöglichen.
- KonferenzbeitragRevenue maximisation in peer-to-peer networks(Kommunikation in Verteilten Systemen (KiVS), 2005) Eger, Kolja; Killat, UlrichBitTorrent is a peer-to-peer (p2p) protocol for file-sharing. Its improvement over other file-sharing protocols is its tit-for-tat strategy to decide to whom a peer should upload. This means that an upload to a peer depends on the download from that peer. This paper investigates the BitTorrent upload algorithm and proposes a new algorithm which is based on a distributed optimisation problem where each peer maximises its own revenue. First simulation results show that the proposed algorithm outperforms the BitTorrent choking algorithm with respect to efficiency and fairness.
- KonferenzbeitragThe FOKUS open SIP AS - A service platform for NGN(Kommunikation in Verteilten Systemen (KiVS), 2005) Fasel, Elmar; Knüttel, Karsten; Magedanz, ThomasEvolutionary, a Next Generation Network (NGN) is a significant improvement of a successfully existing network. The third Generation Partnership Project (3GPP) aimed to merge two of the most successful paradigms in communications: cellular networks and the Internet. Within the IP Multimedia Subsystem (IMS) the 3GPP specified a comprehensive and service oriented architecture that includes session based Quality of Service in IP, charging mechanisms and offers standardized interfaces for application service integration and seamless interactions with legacy services. Under this technical premise a variety of promising value added services suppose to attend our entire communication life. Fraunhofer Institute FOKUS designed and implemented a 3GPP compliant Application Server for converged services called the 'Open SIP AS' which is deploying services within the 'National Host for 3Gb Applications Testbed' on top of an IMS architecture. This paper describes details of the implementation and the usage of the 'Open SIP AS' and gives an example of a NGN service.
- KonferenzbeitragInfluence of the size of swapping entities in mobile P2P file-sharing networks(Kommunikation in Verteilten Systemen (KiVS), 2005) Hoßfeld, Tobias; Tutschku, Kurt; Schlosser, DanielThe performance of an eDonkey-based mobile P2P file-sharing system is investigated by means of time-dynamic simulations. We show in detail that the sizes of the swapping entities, i.e. chunks and blocks, influence the time required for downloading a file. The performance depends on mobile P2P specific factors, like the access technology or the size of typical contents of mobile users.
- KonferenzbeitragReconfigurable consumer direct logistics systems(Kommunikation in Verteilten Systemen (KiVS), 2005) Truchat, Sébastien; Pflaum, AlexanderThe goals of the interdisciplinary project HORN were as well to improve competitiveness of service providers that deliver grocery items as to develop new hardware and software needed for its realisation. In the first part, we introduce this home replenishment project, and analyse the needs and challenges of mobile services with similar constraints. In the second part, we introduce our modular software engineering approach and especially present the adopted reconfiguration mechanism for autonomous mobile applications, and its profiling concept.
- KonferenzbeitragA self-organizing job scheduling algorithm for a distributed VDR(Kommunikation in Verteilten Systemen (KiVS), 2005) Kutzner, Kendy; Cramer, Curt; Fuhrmann, Thomas
- KonferenzbeitragParlay PAM in 3GPP's IP-multimedia subsystem(Kommunikation in Verteilten Systemen (KiVS), 2005) Klaus, Jens-Michael; Magedanz, ThomasThe document will give a brief overview of the Presence and Availability -specification in general, protocols used in the IP Multimedia Subsystem - namely SIP and Diameter - and will show a possible mapping for PAM-methods to the underlying infrastructure. In addition it will describe the IMS infrastructure developed at Fraunhofer Fokus and the implementation of the PAM-server
- KonferenzbeitragCaching for improved retrieval in peer-to-peer networks(Kommunikation in Verteilten Systemen (KiVS), 2005) Balke, Wolf-Tilo; Nejdl, Wolfgang; Siberski, Wolf; Thaden, UweIn modern information systems the dominant retrieval paradigms have shifted from exact matching towards retrieving a list of the most relevant objects. This is because users usually are not satisfied by arbitrarily large and unordered answer sets, but rather interested in small sets of ”best” answers. All popular ranking approaches need collection-wide information. This poses a challenge in the P2P context where each peer has only local knowledge. We discuss how to deal with collection-wide information in P2P networks and how to optimize query distribution based on query result analysis, and present evaluation results.