Now showing 1 - 10 of 78
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JASMINE: A Java tool for multimedia collaboration on the internet

2003 , Shirmohammadi, S. , Saddik, A. el , Georganas, N.D. , Steinmetz, R.

Although collaboration tools have existed for a long time [8], Internet-based multimedia collaboration has recently received a lot of attention mainly due to easy accessibility of the Internet by ordinary users. The Java platform and programming language has also introduced yet another level of easy access: platform-independent computing. As a result, it is very attractive to use Java to design multimedia collaboration systems for the Internet. Today there are many systems, which use Java for multimedia collaboration. However, most of these systems require the shared Java application to be re-written according to the collaboration system's Application Programming Interface (API)-a task which is sometimes difficult or even impossible. In this paper, we describe a practical approach for transparent collaboration with Java. Our approach is transparent in that the Java application can be shared as is with no modifications. The main idea behind our system is that user events occurring through the interactions with the application can be caught, distributed, and reconstructed, hence allowing Java applications to be shared transparently. Our architecture allows us to make the huge installed base of Java applications collaborative, without any modification to their original code. We also prove the feasibility of our architecture by implementation of the JASMINE 1 prototype.

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Verfahren zur Diensteerkennung und Diensteinformationsbereitstellung im Vergleich

2002 , Kirchner, H. , Schönfeld, W. , Steinmetz, R.

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On the aggregation of deterministic service flows

2001 , Schmitt, J. , Karsten, M. , Steinmetz, R.

It is common belief that "flat" Quality of Service (QoS) architectures, e.g. the IETFs Integrated Services architecture (IntServ), are not scalable to large networks, e.g. the global Internet. This is due to the ambitious goal of providing per-flow QoS and the resulting complexity of fine-grained traffic management. One solution to this problem is the aggregation of traffic flows in the core of the network, thus creating a hierarchical resource allocation system. While one might suspect that aggregation leads to allocating more resources for the aggregated flow than for the sum of the separated flows if flow isolation shall be guaranteed deterministically, we show in this article that for IntServ's Guaranteed Service flows this is not necessarily the case even if flow isolation is retained. We compare different approaches to describe the aggregated traffic and analyze their impact on bandwidth consumption and ease of flow management. Furthermore, we perform a thorough numerical evaluation of the derived results with respect to their behavior in response to changes in exogenous parameters like the traffic specifications of the flows or the configuration of the network. Applications of these theoretical insights and numerical evidence could be to use the derived formulae for resource allocation in either a hierarchical IntServ, IntServ over DiffServ (Differentiated Services), or IntServ over ATM (Asynchronous Transfer Mode) network.

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A framework for group integrity management in multimedia multicasting

2001 , Meissner, A. , Wolf, L. , Schönfeld, W. , Steinmetz, R.

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Security for Ad-Hoc Service Information - Threat Analysis of the Service Location Protocol

2002 , Hollick, M. , Steinmetz, R.

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Modeling IP-based mobility management

2002 , Schönfeld, W. , Meissner, A. , Kirchner, H. , Steinmetz, R.

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Transitivity based enrollment strategy for signature verification systems

2001 , Vielhauer, C. , Steinmetz, R. , Mayerhöfer, A.

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Biometric authentication for ID cards with hologram watermarks

2002 , Croce Ferri, L. , Mayerhöfer, A. , Frank, M. , Vielhauer, C. , Steinmetz, R.

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Verfahren zur Diensteerkennung und Diensteinformationsbereitstellung im Vergleich

2002 , Kirchner, H. , Schönfeld, W. , Steinmetz, R.

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Vulnerabilities and security limitations of current IP telephony systems

2001 , Ackermann, R. , Schumacher, M. , Roedig, U. , Steinmetz, R.

Within the traditional telephone system a certain level of quality and security has been established over the years. If we try to use IP Telephony systems as a core part of our future communication infrastructure (e.g. as classical PBX enhancement or replacement) continuous high availability, stable and error-free operation and the protection of the privacy of the spoken word are challenges, that definitely have to be met. Since manufacturers start deploying new end systems and infrastructure components rather fast now - a critical inspection of their security features and vulnerabilities is mandatory. The critical presentation of the theoretical background of certain vulnerabilities, testing and attacking tools and the evaluation results reveals, that well-known security flaws become part of implementations in the new application area again and the security level of a number of examined solutions is rather insufficient.