http://dl.gi.de/handle/20.500.12116/28405 2026-07-22T22:11:18Z http://dl.gi.de/handle/20.500.12116/28440 Parlay PAM in 3GPP's IP-multimedia subsystem Klaus, Jens-Michael; Magedanz, Thomas Müller, Paul; Gotzhein, Reinhard; Schmitt, Jens B. The 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 2005-01-01T00:00:00Z http://dl.gi.de/handle/20.500.12116/28441 From location to position management: User tracking for location-based services Küpper, Axel; Treu, Georg Müller, Paul; Gotzhein, Reinhard; Schmitt, Jens B. This paper compares traditional location management, which focuses on tracking mobile subscribers in the topology of a cellular network, with position management, which we define to be a set of functions for tracking mobile targets in terms of geographic positions as needed for LBSs. As the air interface is the most limited resource in a mobile network, location management has been optimized with regard to signaling overhead caused by updating location data (and paging) between the terminal and the network. Position management is exposed to the same limitations, but, on the other hand, imposes much stronger requirements with regard to accuracy of position data as well as flexibility of tracking. This paper presents an architecture for tailoring the tracking process according to the special LBS requirements on the one hand and limiting the resulting update traffic at the air interface on the other. The architecture is shared between mobile terminals and an application server, for which we present first details of our implementation. 2005-01-01T00:00:00Z http://dl.gi.de/handle/20.500.12116/28439 Federated Identity Management: Die Notwendigkeit zentraler Koordinationsdienste Hommel, Wolfgang; Reiser, Helmut Müller, Paul; Gotzhein, Reinhard; Schmitt, Jens B. Identity & 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. 2005-01-01T00:00:00Z http://dl.gi.de/handle/20.500.12116/28436 A flexible reflector for media streams Brandt, Jens; Kahmann, Verena; Wolf, Lars Müller, Paul; Gotzhein, Reinhard; Schmitt, Jens B. Reflectors mapping multicast to unicast sessions have been proposed to enable multicast media distribution for clients in non-multicast capable networks. However, existing implementations do not allow clients to modify the session by using VCR-like commands in a flexible way. In this paper we describe the design and implementation of a reflector mapping a multicast or unicast session to several downstream unicast sessions. We show that by applying a separation of control and data path such a flexible reflector can handle true media-on-demand functionality for several scenarios, even for group communication, more efficiently than several unicast sessions. 2005-01-01T00:00:00Z