@inproceedings {INPROC-2002-30, author = {Alexander Leonhardi and Kurt Rothermel}, title = {{Architecture of a Large-scale Location Service}}, booktitle = {Short Paper in Proceedings of the 22nd Conference on Distributed Computing Systems : ICDCS 2002; Vienna, Austria, July 2002}, publisher = {IEEE}, institution = {University of Stuttgart : Collaborative Research Center SFB 627 (Nexus: World Models for Mobile Context-Based Systems), Germany}, pages = {465--466}, type = {Conference Paper}, month = {July}, year = {2002}, keywords = {Location Service; Nexus}, language = {English}, cr-category = {H.0 Information Systems General, C.2.4 Distributed Systems}, ee = {http://csdl.computer.org/comp/proceedings/icdcs/2002/1585/00/15850465.pdf, http://www.nexus.uni-stuttgart.de}, contact = {Alexander.Leonhardi@informatik.uni-stuttgart.de}, department = {University of Stuttgart, Institute of Parallel and Distributed Systems, Distributed Systems}, abstract = {Location-aware services are a promising way of exploiting the special possibilities created by ubiquitous mobile devices and wireless communication. Advanced locationaware applications will require highly accurate information about the geographic location of mobile objects and functionality that goes beyond simply querying the user's position, for example determining all mobile objects inside a certain geographic area. In this paper, we propose a generic large-scale location service, which has been designed with the goal of managing the highly dynamic location information for a large number of mobile objects, thus providing a common infrastructure that can be employed by location-aware applications. We propose a hierarchical distributed architecture, which can efficiently process these queries in a scalable way. To be able to deal with the frequent updates and queries resulting from highly dynamic location information, we propose a data storage component, which makes use of a main memory database.}, url = {http://www2.informatik.uni-stuttgart.de/cgi-bin/NCSTRL/NCSTRL_view.pl?id=INPROC-2002-30&engl=1} } @inproceedings {INPROC-2002-27, author = {Alexander Leonhardi and Christian Nicu and Kurt Rothermel}, title = {{A Map-based Dead-reckoning Protocol for Updating Location Information}}, booktitle = {Proceedings of the 2nd International Workshop on Parallel and Distributed Computing Issues in Wireless Networks and Mobile Computing (IPDPSWPIM 2002)}, address = {Fort Lauderdale, FL, USA}, publisher = {k.A.}, institution = {University of Stuttgart : Collaborative Research Center SFB 627 (Nexus: World Models for Mobile Context-Based Systems), Germany}, type = {Conference Paper}, month = {January}, year = {2002}, language = {English}, cr-category = {H Information Systems}, ee = {www.nexus.uni-stuttgart.de}, department = {University of Stuttgart, Institute of Parallel and Distributed Systems, Distributed Systems}, abstract = {k.A.}, url = {http://www2.informatik.uni-stuttgart.de/cgi-bin/NCSTRL/NCSTRL_view.pl?id=INPROC-2002-27&engl=1} } @inproceedings {INPROC-2002-23, author = {Abdelmajid Khelil and Christian Becker and Jing Tian and Kurt Rothermel}, title = {{An Epidemic Model for Information Diffusion in MANETs}}, booktitle = {Proceedings of the 5th International Workshop on Modeling, Analysis and Simulation of Wireless and Mobile Systems (MSWiM'02) at MobiCom 2002}, editor = {Teresa Dahlberg and Michela Meo and Albert Zomaya}, address = {Atlanta, Georgia, USA}, publisher = {ACM PRESS}, institution = {University of Stuttgart : Collaborative Research Center SFB 627 (Nexus: World Models for Mobile Context-Based Systems), Germany}, series = {ACM MSWiM Proceedings}, pages = {54--60}, type = {Conference Paper}, month = {September}, year = {2002}, isbn = {1-58113-610-2}, keywords = {Algorithms; Performance; Reliability; MANET; analytical modeling; adaptive information diffusion}, language = {English}, cr-category = {C.2.1 Network Architecture and Design, C.2.2 Network Protocols, I.6.5 Model Development}, ee = {ftp://ftp.informatik.uni-stuttgart.de/pub/library/ncstrl.ustuttgart_fi/INPROC-2002-23/INPROC-2002-23.pdf, http://canu.informatik.uni-stuttgart.de/}, contact = {University of Stuttgart / IPVS Breitwiesenstr. 20-22 70565 Stuttgart, Germany +49 711 7816 {251, 357, 228, 434} {khelil, becker, tian, rothermel}@informatik.uni-stuttgart.de}, department = {University of Stuttgart, Institute of Parallel and Distributed High-Performance Systems, Distributed Systems}, abstract = {Choosing appropriate information dissemination strategies is crucial in mobile ad hoc networks (MANET) due to the frequent topology changes. Flooding-based approaches like diffusion have a strong similarity with epidemic spreading of diseases. Applying epidemiological models to information diffusion allows the evaluation of such strategies depending on the MANET characteristics, e.g. the node density. In order to choose appropriate strategies at run time, the model should be easily evaluated. In this paper, an epidemic model is developed for a simple information diffusion algorithm based on simulation results. We analytically investigate the impact of node density on information diffusion. The analytical model allows the evaluation at runtime, even on devices with restricted resources, and thus enables mobile nodes to dynamically adapt their diffusion strategies depending on the local node density.}, url = {http://www2.informatik.uni-stuttgart.de/cgi-bin/NCSTRL/NCSTRL_view.pl?id=INPROC-2002-23&engl=1} } @inproceedings {INPROC-2002-22, author = {Christian Becker and Martin Bauer and J{\"o}rg H{\"a}hner}, title = {{Usenet-on-the-fly - Supporting Locality of Information in Spontaneous Networking Entironments}}, booktitle = {Workshop on Ad Hoc Communications and Collaboration in Ubiquitous Computing Envirnments}, editor = {Ramiro Liscano and Gerd Kortuem}, publisher = {n/a}, institution = {University of Stuttgart : Collaborative Research Center SFB 627 (Nexus: World Models for Mobile Context-Based Systems), Germany}, pages = {1--1}, type = {Conference Paper}, month = {November}, year = {2002}, language = {English}, cr-category = {H.4.3 Information Systems Applications Communications Applications, H.5.3 Group and Organization Interfaces}, ee = {ftp://ftp.informatik.uni-stuttgart.de/pub/library/ncstrl.ustuttgart_fi/INPROC-2002-22/INPROC-2002-22.pdf}, contact = {christian.becker@informatik.uni-stuttgart.de}, department = {University of Stuttgart, Institute of Parallel and Distributed High-Performance Systems, Distributed Systems}, abstract = {People on the move are typically interested in information with respect to their proximity. Location-based services in general supply users with information about their proximity typically relying on an infrastructure storing the information and tracking the mobile objects, i.e. users. In this paper we present an approach for spontaneous, i.e. ad hoc, networks inspired by the Usenet. Information is exchanged using a peer-to-peer synchronization mechanism. The information is made available through channels grouping related information. The information propagation is solely based on spontaneously connected devices not requiring any infrastructure. Our prototype implementation shows the technical feasibility of our approach, whereas simulation results show the applicability of information diffusion in outdoor scenarios with a realistic number of nodes, covering a city center.}, url = {http://www2.informatik.uni-stuttgart.de/cgi-bin/NCSTRL/NCSTRL_view.pl?id=INPROC-2002-22&engl=1} } @inproceedings {INPROC-2002-21, author = {Daniel Herrscher and Kurt Rothermel}, title = {{A Dynamic Network Scenario Emulation Tool}}, booktitle = {Proceedings of the 11th International Conference on Computer Communications and Networks (ICCCN 2002), Miami (FL), Oct 14-16, 2002}, publisher = {IEEE}, institution = {University of Stuttgart, Faculty of Computer Science, Germany}, pages = {262--267}, type = {Conference Paper}, month = {October}, year = {2002}, isbn = {0-7803-7553-X}, keywords = {Network Emulation; Network Scenario; Emulation Tool}, language = {English}, cr-category = {C.2.1 Network Architecture and Design, C.2.2 Network Protocols}, ee = {ftp://ftp.informatik.uni-stuttgart.de/pub/library/ncstrl.ustuttgart_fi/INPROC-2002-21/INPROC-2002-21.pdf}, contact = {herrscher@informatik.uni-stuttgart.de}, department = {University of Stuttgart, Institute of Parallel and Distributed High-Performance Systems, Distributed Systems}, abstract = {Comparative performance measurements of distributed applications and network protocols require the availability of appropriate network environments. Network emulation approaches offer a flexible way to mimic the properties of a variety of networks. Existing emulation tools work either with centralized real-time simulation components, limiting the scenario size and maximum traffic, or focus on the emulation of some network properties at a single point. We propose a tool for the realistic emulation of network links, and show how several emulated links can be combined to reproduce a comprehensive network model. In addition to that, the model can include changing network properties, e.g. emerging from mobile communication partners. This facilitates the distributed emulation of a comprehensive, dynamic network scenario to support repeatable performance measurements.}, url = {http://www2.informatik.uni-stuttgart.de/cgi-bin/NCSTRL/NCSTRL_view.pl?id=INPROC-2002-21&engl=1} } @inproceedings {INPROC-2002-20, author = {Detlef Bosau and Cora Burger and Arno Wacker and Martin Pfletschinger}, title = {{Context-Sensitive Interaction Support during Augmented Lectures}}, booktitle = {Proceedings of the 7th Cabernet Radicals Workshop}, editor = {Joe Finney and Mads Haahr and Alberto Montresor}, address = {Bertinoro (Forly, Italy)}, publisher = {-}, institution = {University of Stuttgart, Faculty of Computer Science, Germany}, type = {Conference Paper}, month = {October}, year = {2002}, keywords = {e-learning; Application sharing; teaching; mobile computing}, language = {English}, cr-category = {H.4.3 Information Systems Applications Communications Applications}, ee = {ftp://ftp.informatik.uni-stuttgart.de/pub/library/ncstrl.ustuttgart_fi/INPROC-2002-20/INPROC-2002-20.pdf, http://www.newcastle.research.ec.org/cabernet/, http://www.informatik.uni-stuttgart.de/ipvr/vs/en/projects/NUSS/}, contact = {Send an E-Mail to Arno.Wacker@informatik.uni-stuttgart.de or phone +49-711-7816-236}, department = {University of Stuttgart, Institute of Parallel and Distributed High-Performance Systems, Distributed Systems}, abstract = {With mobile devices and wireless networks, new possibilities evolve to improve the interaction between teacher and students in class. The paper introduces the idea of DONUT, a Distributed annOtation tool for Notebook University Teachware, which is going to be developed within the NUSS (Notebook University Stuttgart) project being funded by the German Ministry for Education and Research. DONUT is integrated into an existing framework for application sharing. It is based on defining and making use of semantic relationships between presented teaching material and contributions of students. Hence, automatic categorization of contributions becomes available in advance. This supports the teacher's decision, whether to integrate contributions into the lecture or postpone them. Especially, a lot of questions regarding the same topic can indicate problems in understanding on the side of students quite well.}, url = {http://www2.informatik.uni-stuttgart.de/cgi-bin/NCSTRL/NCSTRL_view.pl?id=INPROC-2002-20&engl=1} } @inproceedings {INPROC-2002-19, author = {Martin Bauer and Kurt Rothermel}, title = {{Towards the Observation of Spatial Events in Distributed Location-Aware Systems}}, booktitle = {Proceedings of the 22nd International Conference on Distributed Computing Systems Workshops}, editor = {Roland Wagner}, address = {Los Alamitos, California}, publisher = {IEEE Computer Society}, institution = {University of Stuttgart : Collaborative Research Center SFB 627 (Nexus: World Models for Mobile Context-Based Systems), Germany}, pages = {581--582}, type = {Conference Paper}, month = {July}, year = {2002}, isbn = {0-7695-1588-6}, keywords = {event; event observation; location awareness; Nexus}, language = {English}, cr-category = {C.2.4 Distributed Systems}, ee = {http://www.computer.org/proceedings/icdcsw/1588/15880581.pdf, http://www.nexus.uni-stuttgart.de}, contact = {Martin Bauer Martin.Bauer@informatik.uni-stuttgart.de}, department = {University of Stuttgart, Institute of Parallel and Distributed High-Performance Systems, Distributed Systems}, abstract = {In this paper, the event concept is applied to support the interaction between mobile users and distributed location-aware systems. Taking a number of examples, the components of an event specification language are derived that can be used beyond the domain of location-aware systems.}, url = {http://www2.informatik.uni-stuttgart.de/cgi-bin/NCSTRL/NCSTRL_view.pl?id=INPROC-2002-19&engl=1} } @inproceedings {INPROC-2002-16, author = {Daniel Herrscher and Alexander Leonhardi and Kurt Rothermel}, title = {{Modeling Computer Networks for Emulation}}, booktitle = {Proceedings of the 2002 International Conference on Parallel and Distributed Processing Techniques and Applications (PDPTA'02), Las Vegas}, publisher = {CSREA Press}, institution = {University of Stuttgart, Faculty of Computer Science, Germany}, pages = {1725--1731}, type = {Conference Paper}, month = {June}, year = {2002}, keywords = {Network Emulation; Modeling Language; Network Topologies}, language = {English}, cr-category = {C.2.1 Network Architecture and Design, C.2.5 Local and Wide-Area Networks}, ee = {ftp://ftp.informatik.uni-stuttgart.de/pub/library/ncstrl.ustuttgart_fi/INPROC-2002-16/INPROC-2002-16.pdf}, contact = {herrscher@informatik.uni-stuttgart.de}, department = {University of Stuttgart, Institute of Parallel and Distributed High-Performance Systems, Distributed Systems}, abstract = {The Network Emulation Testbed project provides a configurable network environment for the performance analysis of distributed applications and protocols. An emulation scenario consists of a network topology, link parameters, and dynamic change models. In order to set up a scenario automatically, it has to be modeled in an appropriate description language. In this paper, we analyze the requirements for an emulation scenario description language and propose a possible solution.}, url = {http://www2.informatik.uni-stuttgart.de/cgi-bin/NCSTRL/NCSTRL_view.pl?id=INPROC-2002-16&engl=1} } @inproceedings {INPROC-2002-15, author = {Xuejun Chen}, title = {{Dynamic Reconfiguration of a Component-Based Software System for Vehicles}}, booktitle = {Proceeding of the 15th IFAC World Congress on Automatic Control}, address = {Oxford, UK}, publisher = {Elsevier Science Ltd.}, institution = {University of Stuttgart, Faculty of Computer Science, Germany}, pages = {1--1}, type = {Conference Paper}, month = {July}, year = {2002}, keywords = {Mobile Application; Dynamic Reconfiguration; Distributed System; Update Strategy; Component Deployment Strategy}, language = {English}, cr-category = {D.2 Software Engineering}, department = {University of Stuttgart, Institute of Parallel and Distributed High-Performance Systems, Distributed Systems}, abstract = {The component system information and management architecture is a component architecture to build the application software which is used in modern vehicles. The components are distributed in the system: the individual components are mainly located in different computers in vehicles, while the rest runs on computers in the infrastructure. The components can be dynamically loaded to different places of the component system, executed, removed and updated at runtime. In this article, we describe dynamic reconfiguration of a software component system for vehicles. Furthermore, we propose update strategies for updating components and component deployment strategies for optimizing the distributed system. By the use of dynamic reconfiguration, the flexibility and adaptability of the component based distributed system in vehicles are enhanced. In addition, the dynamic reconfiguration can improve the performance of the component system and reduce the costs of communication between a vehicle and the infrastructure.}, url = {http://www2.informatik.uni-stuttgart.de/cgi-bin/NCSTRL/NCSTRL_view.pl?id=INPROC-2002-15&engl=1} } @inproceedings {INPROC-2002-14, author = {Xuejun Chen and Martin Simons}, title = {{A Component Framework for Dynamic Reconfiguration of Distributed Systems}}, booktitle = {Proceeding of the First International IFIP/ACM Working Conference on Component Deployment (CD 2002)}, publisher = {Springer Verlag}, institution = {University of Stuttgart, Faculty of Computer Science, Germany}, series = {Lecture Notes in Computer Science}, pages = {1--1}, type = {Conference Paper}, month = {June}, year = {2002}, language = {English}, cr-category = {D.2 Software Engineering}, department = {University of Stuttgart, Institute of Parallel and Distributed High-Performance Systems, Distributed Systems}, abstract = {The growing popularity of wired and wireless Internet requires distributed systems to be more flexible, adaptive and easily extendable. Dynamic reconfiguration of distributed component-based systems is one possible solution to meet these demands. However, current component frameworks that support dynamic reconfiguration either place the burden of preparing a component for reconfiguration completely on the component's developer or impose strong restrictions on the component model and the communication mechanisms. We investigate a middle ground between these two extremes and propose a component framework that supports a framework guided reconfiguration and places minimal burden on the component's developer. This component framework offers mechanisms to analyze and treat the interactions between the target component and other components during a dynamic reconfiguration.}, url = {http://www2.informatik.uni-stuttgart.de/cgi-bin/NCSTRL/NCSTRL_view.pl?id=INPROC-2002-14&engl=1} } @inproceedings {INPROC-2002-13, author = {Xuejun Chen}, title = {{Extending RMI to Support Dynamic Reconfiguration of Distributed Systems}}, booktitle = {Proceeding of the 22nd International Conference on Distributed Computing Systems (ICDCS 2002)}, publisher = {IEEE Computer Society}, institution = {University of Stuttgart, Faculty of Computer Science, Germany}, pages = {1--1}, type = {Conference Paper}, month = {July}, year = {2002}, keywords = {Java RMI; Middleware; Dynamic Reconfiguration; Mobile Object; Distributed Systems}, language = {English}, cr-category = {C.2 Computer-Communication Networks, D.1 Programming Techniques}, department = {University of Stuttgart, Institute of Parallel and Distributed High-Performance Systems, Distributed Systems}, abstract = {By the use of the ability of dynamic reconfiguration, the flexibility, adaptability, and extensibility of distributed systems are enhanced. How to treat interactions among components during a dynamic reconfiguration is still one of the most crucial problems in this research area. This challenge should be met by middleware design and development. However, the current standard middleware offers little support for dynamic reconfiguration of distributed systems. In this paper, we describe an extended Java RMI that supports efficiently dynamic reconfiguration of distributed systems. This extended Java RMI can automatically monitor and manipulate invocations between components during a dynamic reconfiguration. Moreover, the extended Java RMI can automatically switch invocations from remote to local and vice versa.}, url = {http://www2.informatik.uni-stuttgart.de/cgi-bin/NCSTRL/NCSTRL_view.pl?id=INPROC-2002-13&engl=1} } @inproceedings {INPROC-2002-11, author = {Uwe Kubach and Kurt Rothermel}, title = {{Estimating the Benefit of Location-Awareness for Mobile Data Management Mechanisms}}, booktitle = {Proceedings of the International Conference on Pervasive Computing 2002}, address = {Heidelberg}, publisher = {Springer-Verlag}, institution = {University of Stuttgart : Collaborative Research Center SFB 627 (Nexus: World Models for Mobile Context-Based Systems), Germany}, pages = {1--14}, type = {Conference Paper}, month = {August}, year = {2002}, keywords = {location awareness; mobile data management; evaluation}, language = {English}, cr-category = {H.2 Database Management}, ee = {ftp://ftp.informatik.uni-stuttgart.de/pub/library/ncstrl.ustuttgart_fi/INPROC-2002-11/INPROC-2002-11.pdf}, department = {University of Stuttgart, Institute of Parallel and Distributed High-Performance Systems, Distributed Systems}, abstract = {With the increasing popularity of mobile computing devices, the need to access information in mobile environments has also grown rapidly. In order to support such mobile information accesses, location-based services and mobile information systems often rely on location-aware data management mechanisms like location-aware caching, data dissemination or prefetching. As we explain in this paper, the location-awareness of such mechanisms is only useful, if the accessed information is location-dependent, i.e. if the probability with that a certain information object is accessed depends on the user’s location. Although the location-dependency of the accessed information is crucial for the efficiency of location-aware data management mechanisms and the benefit they can get out of their location-awareness, no metric to measure the location-dependency of information has been proposed so far. In this paper, we describe such a metric together with a second one for a further important characteristic of mobile information accesses, the so-called focus.}, url = {http://www2.informatik.uni-stuttgart.de/cgi-bin/NCSTRL/NCSTRL_view.pl?id=INPROC-2002-11&engl=1} } @inproceedings {INPROC-2002-10, author = {Jing Tian and J{\"o}rg H{\"a}hner and Christian Becker and Illya Stepanov and Kurt Rothermel}, title = {{Graph-Based Mobility Model for Mobile Ad Hoc Network Simulation}}, booktitle = {Proceedings of the 35th Annual Simulation Symposium: San Diego, California, April 14-18, 2002}, editor = {IEEE Computer Society Press}, address = {Washington, Brussels, Tokyo}, publisher = {IEEE Computer Society Press}, institution = {University of Stuttgart, Faculty of Computer Science, Germany}, pages = {337--345}, type = {Conference Paper}, month = {April}, year = {2002}, isbn = {0-7695-1552-5}, keywords = {Mobility Model; Mobile Ad Hoc Network; Simulation; Spatial Model}, language = {English}, cr-category = {I.6 Simulation and Modeling, G.3 Probability and Statistics}, contact = {canu@informatik.uni-stuttgart.de}, department = {University of Stuttgart, Institute of Parallel and Distributed High-Performance Systems, Distributed Systems}, abstract = {Imagine a world where people constantly try to pass through walls and cars suddenly leave the roads and drive into rivers. Although this is unrealistic, most simulations for mobile ad hoc networks so far are based on the so called ``random walk'' of mobile objects, which are not constrained by their surrounding spatial environments. In this paper we propose a novel graph-based mobility model, which provides a more realistic movement than the random walk model by reflecting the spatial constraints in the real world. We analyzed three commonly used ad hoc network routing protocols, DSDV, DSR and AODV with both a random walk-based and our graph-based mobility model. Our simulation results show that the spatial constraints have a strong impact on the performance of ad hoc routing protocols.}, url = {http://www2.informatik.uni-stuttgart.de/cgi-bin/NCSTRL/NCSTRL_view.pl?id=INPROC-2002-10&engl=1} } @inproceedings {INPROC-2002-09, author = {Joachim Jordan and Ulrich Kleinhans and Ottokar Kulendik and J{\"u}rgen Porscha and Alwin Pross and Reiner Siebert}, title = {{Transparent and Flexible Cross-Organizational Workflows for Engineering Cooperations in Vehicle Development}}, booktitle = {PDT Europe 2002}, address = {Torino, Italy}, publisher = {Quality Marketing Services, Sandhurst, UK}, institution = {University of Stuttgart, Faculty of Computer Science, Germany}, pages = {101--108}, type = {Conference Paper}, month = {May}, year = {2002}, isbn = {1 901782 06 9}, keywords = {cross-organizational workflow management; engineering}, language = {English}, cr-category = {H.5.3 Group and Organization Interfaces, C.2.4 Distributed Systems, H.4.1 Office Automation, J.1 Administration Data Processing, J.2 Physical Sciences and Engineering}, contact = {ottokar.kulendik@informatik.uni-stuttgart.de}, department = {University of Stuttgart, Institute of Parallel and Distributed High-Performance Systems, Distributed Systems}, abstract = {Engineering cooperations for vehicle development have proven to be successful not just to extend capacities but to profit from each other's specific know-how. Workflow management bears the potential to reduce cooperation barriers and costs. Within a cooperation project between DaimlerChrysler AG and EDAG, application scenarios have been defined to identify goals and benefits, to analyse important requirements, and to develop an IT solution concept, together with the University of Stuttgart. Manufacturer and supplier both would profit from 1.) manageable automation of cross-organizational workflows, 2.) transparency of their partner's processes, 3.) flexibility of specifying own workflows autonomously, and 4.) integration of heterogeneous workflow management systems. For research, this field of application is challenging because existing approaches so far do not seem to be sufficient. We describe a relevant scenario from an engineering cooperation project in detail. The resulting requirements do not only occur across companies, but in general even inside a single company. An appropriate solution should be able to deal with multiple interactions and some more complex dependencies between different workflows. It should be possible to make relevant data visible but keep irrelevant information private, and to support a late evolution of partner's workflows. To address those requirements appropriately, our approach minimizes the specification agreed between the partners, therefore allowing to specify the associated partner's workflows in a decentralized, delayed manner. External workflow schemata can be used to give partners a view on each other's workflow. We use a peer-to-peer architecture in which complex dependencies between workflows are mapped onto simpler messages.}, url = {http://www2.informatik.uni-stuttgart.de/cgi-bin/NCSTRL/NCSTRL_view.pl?id=INPROC-2002-09&engl=1} } @inproceedings {INPROC-2002-08, author = {Peter Coschurba and Kurt Rothermel and Frank D{\"u}rr}, title = {{A fine grained addressing concept for GeoCast}}, booktitle = {Trends in Network and Pervasive Computing -- ARCS 2002 (Proceedings of the International Conference on Architecture of Computing Systems 2002)}, editor = {Hartmut Schmeck and Theo Unger and Lars Wolf}, address = {Karlsruhe, Germany}, publisher = {Springer-Verlag}, institution = {University of Stuttgart : Collaborative Research Center SFB 627 (Nexus: World Models for Mobile Context-Based Systems), Germany}, series = {Lecture Notes in Computer Science}, volume = {2299}, pages = {101--113}, type = {Conference Paper}, month = {April}, year = {2002}, isbn = {3-540-43409-7}, keywords = {routing; location-based services; geographic communication; GeoCast}, language = {English}, cr-category = {C.2 Computer-Communication Networks}, ee = {ftp://ftp.informatik.uni-stuttgart.de/pub/library/ncstrl.ustuttgart_fi/INPROC-2002-08/INPROC-2002-08.pdf, http://www.springerlink.com/content/8hcep0e11k61tx53/}, department = {University of Stuttgart, Institute of Parallel and Distributed Systems, Distributed Systems}, abstract = {GeoCast provides the functionality of sending messages to everyone in a specific area. So far, only the addressing of larger two-dimensional areas was possible. For the use in an urban environment it is crucial that small and three-dimensional areas can be addressed. For example, GeoCast can then be used to send lecture notes to all in a classroom. In this paper we describe a fine-grained addressing concept for GeoCast that supports such areas. In addition we present an architecture that allows the use of that addressing concept together with the GeoRouting-approach developed by Navas and Imielinski. We also present some modifications necessary to enhance the scalability of GeoCast.}, url = {http://www2.informatik.uni-stuttgart.de/cgi-bin/NCSTRL/NCSTRL_view.pl?id=INPROC-2002-08&engl=1} } @inproceedings {INPROC-2002-06, author = {Cora Burger and Stella Papakosta and Eric Bullinger and Thomas Wagner}, title = {{Investigation of application sharing systems for teaching purposes in engineering disciplines}}, booktitle = {4th International Conference on New Educational Environment 2002}, publisher = {EduSwiss}, institution = {University of Stuttgart, Faculty of Computer Science, Germany}, type = {Conference Paper}, month = {May}, year = {2002}, keywords = {Application Sharing; Wireless Campus; Awareness}, language = {English}, cr-category = {H.4.3 Information Systems Applications Communications Applications}, ee = {http://www.informatik.uni-stuttgart.de/ipvr/vs/projekte/Festival/sascia.html, http://www.eduswiss.ch/4th-conf/default.asp}, contact = {caburger@informatik.uni-stuttgart.de}, department = {University of Stuttgart, Institute of Parallel and Distributed High-Performance Systems, Distributed Systems}, abstract = {With portable devices and wireless networks, a new potential is arising to improve teaching in collocated, remote and hybrid scenarios. This can be achieved by a suitable mixture of theoretical and practical elements, where students can try out applications by themselves during lectures. Existing systems for application sharing do not cope with the specific requirements of this environment. Hence, the system SASCIA (System architecture supporting cooperative and interactive applications) has been developed and tested successfully.}, url = {http://www2.informatik.uni-stuttgart.de/cgi-bin/NCSTRL/NCSTRL_view.pl?id=INPROC-2002-06&engl=1} } @inproceedings {INPROC-2002-04, author = {Cora Burger and Stella Papakosta and Kurt Rothermel}, title = {{Application sharing in teaching context with wireless networks}}, booktitle = {Proc. World Congress NETWORKED LEARNING IN A GLOBAL ENVIRONMENT - Challenges and Solutions for Virtual Education}, publisher = {NAISO (Natural and Artificial Intelligence Systems Organization) The Netherlands}, institution = {University of Stuttgart, Faculty of Computer Science, Germany}, type = {Conference Paper}, month = {May}, year = {2002}, keywords = {Application sharing; teaching}, language = {English}, cr-category = {H.4.3 Information Systems Applications Communications Applications}, ee = {http://www.icsc-naiso.org/conferences/nl2002/, http://www.informatik.uni-stuttgart.de/ipvr/vs/projekte/Festival/sascia.engl.html}, contact = {caburger@informatik.uni-stuttgart.de}, department = {University of Stuttgart, Institute of Parallel and Distributed High-Performance Systems, Distributed Systems}, abstract = {The success of teaching is depending on a couple of factors where collaboration among all participants, teachers and students are the most important ones. With mobile devices and wireless networks, new possibilities evolve for improvement. By promoting existing concepts of application sharing systems, the project SASCIA (System architecture supporting cooperative and interactive applications) aims at developing a framework for multiple applications to support teaching in collocated, remote and hybrid scenarios. It provides annotation and recording to support latecomers and further exceptions as well as subsequent replay. Moreover, configurable context awareness among participants as well as floor and consistency control cover a wide spectrum of applications and learning situations. According to first experiments, the prototype is performing well and was readily accepted by students.}, url = {http://www2.informatik.uni-stuttgart.de/cgi-bin/NCSTRL/NCSTRL_view.pl?id=INPROC-2002-04&engl=1} } @inproceedings {INPROC-2002-02, author = {Cora Burger and Eric Bullinger and Stella Papakosta and Thomas Wagner}, title = {{Context awareness for application sharing in teaching environment}}, booktitle = {International Conference on Advances in Infrastructure for e-Business, e-Education, e-Science, and e-Medicine on the Internet}, publisher = {Scuola Superiore G. Reiss Romoli}, institution = {University of Stuttgart, Faculty of Computer Science, Germany}, pages = {00--00}, type = {Conference Paper}, month = {January}, year = {2002}, keywords = {Application sharing, context awareness, teaching}, language = {English}, cr-category = {H.4.3 Information Systems Applications Communications Applications, H.5.3 Group and Organization Interfaces, J.1 Administration Data Processing}, ee = {ftp://ftp.informatik.uni-stuttgart.de/pub/library/ncstrl.ustuttgart_fi/INPROC-2002-02/INPROC-2002-02.ps, http://www.ssgrr.it/en/ssgrr2002w/index.htm, http://www.informatik.uni-stuttgart.de/ipvr/vs/projekte/Festival/sascia.html}, contact = {caburger@informatik.uni-stuttgart.de}, department = {University of Stuttgart, Institute of Parallel and Distributed High-Performance Systems, Distributed Systems}, abstract = {Mobile and ubiquitous computing offer new possibilities to increase the awareness in class and support an active participation of students. To this end, context information is captured and distributed about sessions, participants and those applications that are used during a lecture or encounter among students (e. g. presentations, development and simulation environments, experiments in natural and engineering sciences). The framework of SASCIA (System Architecture Supporting Cooperative and Interactive Applications) cares for appropriate usage of this information to enable new ways of application sharing. First experiments have proofed the usefulness of the system and an acceptable performance.}, url = {http://www2.informatik.uni-stuttgart.de/cgi-bin/NCSTRL/NCSTRL_view.pl?id=INPROC-2002-02&engl=1} } @article {ART-2002-05, author = {Christian Hauser and Alexander Leonhardi and Paul J. K{\"u}hn}, title = {{Sicherheitsaspekte in Nexus - einer Plattform f{\"u}r ortsbezogene Anwendungen}}, journal = {it+ti, Zeitschrift f{\"u}r Informationstechnik und Technische Informatik}, address = {M{\"u}nchen}, publisher = {Oldenbourg}, volume = {5}, pages = {268--277}, type = {Article in Journal}, month = {October}, year = {2002}, isbn = {0944-2774}, language = {German}, cr-category = {H Information Systems}, ee = {www.nexus.uni-stuttgart.de}, department = {University of Stuttgart, Institute of Parallel and Distributed Systems, Distributed Systems; Universit{\"a}t Stuttgart, Institut f{\"u}r Kommunikationsnetze und Rechnersysteme (IKR)}, abstract = {abstract}, url = {http://www2.informatik.uni-stuttgart.de/cgi-bin/NCSTRL/NCSTRL_view.pl?id=ART-2002-05&engl=1} } @article {ART-2002-04, author = {Martin Bauer and Christian Becker and Kurt Rothermel}, title = {{Location Models from the Perspective of Context-Aware Applications Mobile Ad Hoc Networks}}, journal = {Personal and Ubiquitous Computing}, address = {London}, publisher = {Springer-Verlag}, volume = {6}, number = {5-6}, pages = {322--328}, type = {Article in Journal}, month = {December}, year = {2002}, issn = {1617-4909}, keywords = {context-awareness; location models; ubiquitous computing; MANET; Nexus}, language = {English}, cr-category = {C.2.4 Distributed Systems, D.2.12 Software Engineering Interoperability, H.2.3 Database Management Languages}, ee = {http://link.springer.de/link/service/journals/00779/bibs/2006005/20060322.htm, http://www.nexus.uni-stuttgart.de}, contact = {Martin Bauer Martin.Bauer@informatik.uni-stuttgart.de}, department = {University of Stuttgart, Institute of Parallel and Distributed High-Performance Systems, Distributed Systems}, abstract = {Location models are crucial for providing location-dependent data to context-aware applications. In this paper, we present two approaches for modeling location information taken from an infrastructure-based and an ad hoc network-based application scenario. From these approaches we derive requirements for a general location modeling language for ubiquitous computing.}, url = {http://www2.informatik.uni-stuttgart.de/cgi-bin/NCSTRL/NCSTRL_view.pl?id=ART-2002-04&engl=1} } @article {ART-2002-01, author = {Christian Maih{\"o}fer and Kurt Rothermel}, title = {{Optimal Branching Factor for Tree-based Reliable Multicast Protocols}}, journal = {Computer Communications}, editor = {Elsevier}, publisher = {Elsevier}, type = {Article in Journal}, month = {January}, year = {2002}, language = {English}, cr-category = {C.2 Computer-Communication Networks}, ee = {ftp://ftp.informatik.uni-stuttgart.de/pub/library/ncstrl.ustuttgart_fi/ART-2002-01/ART-2002-01.pdf, ftp://ftp.informatik.uni-stuttgart.de/pub/library/ncstrl.ustuttgart_fi/ART-2002-01/ART-2002-01.ps}, contact = {christian.maihoefer@informatik.uni-stuttgart.de}, department = {University of Stuttgart, Institute of Parallel and Distributed High-Performance Systems, Distributed Systems}, abstract = {In recent years, many reliable multicast protocols on transport layer have been proposed. Previous analysis and simulation studies gave evidence for the superiority of tree-based approaches in terms of throughput and bandwidth requirements. In many tree-based protocols, the nodes of the tree are formed of multicast group members. In this case, the branching factor, i.e. the maximum number of child nodes is adjustable. In this paper we analyze the influence of the branching factor on a protocol's throughput and bandwidth consumption. This knowledge is important to configure protocols for best performance and to optimize the tree creation process. Our results show that the optimal branching factor depends mainly on the probability for receiving messages from other local groups. If local groups are assigned to a separate multicast address, the optimal branching factor is small. On the other hand, if TTL scoping is used and therefore the probability for receiving messages from other local groups is greater than zero, larger local groups provide better performance.}, url = {http://www2.informatik.uni-stuttgart.de/cgi-bin/NCSTRL/NCSTRL_view.pl?id=ART-2002-01&engl=1} }