717 research outputs found
An analysis framework for CSCW systems
Software toolkits are under development to help construct applications that support
group-working. Toolkit developers adopt different approaches to group-work support
in order to tackle different issues and a toolkit is commonly characterised by the
approach adopted. It is difficult to compare toolkits because of this lack of apparent
commonality and it is difficult to decide which toolkits meet specific application
requirements. [Continues.
State of the art survey of network operating systems development
The results of the State-of-the-Art Survey of Network Operating Systems (NOS) performed for Goddard Space Flight Center are presented. NOS functional characteristics are presented in terms of user communication data migration, job migration, network control, and common functional categories. Products (current or future) as well as research and prototyping efforts are summarized. The NOS products which are revelant to the space station and its activities are evaluated
Multimedia-Streaming in Benutzergruppen
At the time being, multimedia services using IP technology like IPTV or video on-demand are a hot topic. Technically, they can be classified under the notion of streaming. A server sends media data in a continuous fashion to one or several clients, which consume and display data portions as soon as they arrive. Using a feedback channel customers may influence the play-back, watching programs time-shifted or pausing the program. An enhancement of such streaming services is to watch those movies with a group of people on several devices in parallel. Similar approaches have been developed using IP multicast. However, users cannot control the presentation: pausing or skipping of more unimportant parts is impossible. Moreover, members cannot be added to the session directly within the application. The costream architecture developed in this works offers a collaborative streaming service without these limitations: People may join others watching a movie or invite others to such a collaborative streaming session. Dependent on the desired course of the session the participants' control operations are executed for all users, or the group is split into subgroups to let watchers follow their own time-lines. A group management controls this by means of user roles. Separate from the group management, the so-called association service provides for streaming session control and synchronization among participants. This separation of duties is advantageous in the sense that standard components can be used: For group management, SIP conferencing servers are suitable, whereas session control can best be handled using RTSP proxies as already used for caching of media data. Eventually, the evaluation of this architecture shows that such a service offers both low latency for clients and an acceptable synchronization of media streams to different client devices. Moreover, the communication overhead compared to usual conferencing or streaming systems is very low.Mit Hilfe der IP-Technologie erbrachte Multimedia-Dienste wie IPTV oder Video-on-Demand sind zur Zeit ein gefragtes Thema. Technisch werden solche Dienste unter dem Begriff "Streaming" eingeordnet. Ein Server sendet Mediendaten kontinuierlich an EmpfĂ€nger, welche die Daten sofort weiterverarbeiten und anzeigen. Ăber einen RĂŒckkanal hat der Kunde die Möglichkeit der Einflussnahme auf die Wiedergabe. Eine Weiterentwicklung dieser Streaming-Dienste ist die Möglichkeit, gemeinsam mit anderen denselben Film auf mehreren GerĂ€ten anzusehen. Ăhnliche AnsĂ€tze gibt es im Internet bereits durch IP-Multicast. Allerdings können Benutzer hierbei keinen Einfluss auf die Ăbertragung nehmen - das Ăberspringen von Teilen ist zum Beispiel nicht möglich. Andere Benutzer können nicht direkt zur Streaming-Sitzung eingeladen werden. Collaborative Streaming ohne solche EinschrĂ€nkungen bietet die in dieser Arbeit entwickelte costream-Architektur: Sie erlaubt es, andere zum gemeinsamen Betrachten eines Filmes einzuladen oder sich selbst in eine Benutzergruppe einzuklinken. AbhĂ€ngig vom gewĂŒnschten Ablauf der Sitzung wird die Steuerung fĂŒr alle Teilnehmer durchgefĂŒhrt oder die Gruppe aufgeteilt. Eine Gruppenverwaltung regelt dies mit Hilfe von Rollenzuweisungen. Davon getrennt sorgt eine weitere Komponente fĂŒr die Steuerung der Streaming-Sitzungen und die Synchronisation zwischen Teilnehmern. Diese Aufteilung hat den Vorteil, dass von der IETF entwickelte Standardprotokolle eingesetzt werden können. FĂŒr die Gruppenverwaltung sind SIP-Konferenzsysteme geeignet, wĂ€hrend fĂŒr die Sitzungssteuerung ein RTSP-Zwischensystem benutzt wurde. Die Evaluierung dieser Architektur zeigt schlieĂlich, dass ein solcher Dienst nicht nur geringe Wartezeiten aufweist, sondern eine akzeptable Synchronisation der Datenströme auf die verschiedenen AusgabegerĂ€te der Benutzer erreicht wird. Zudem ist der Zusatzaufwand verglichen mit ĂŒblichen Konferenz- oder Streaming-Systemen sehr gering
Communication Architecture For Distributed Interactive Simulation (CADIS): Rationale Document Draft
Report on necessary communication system protocol data unit standards which must be accepted and adopted for supporting distributed interactive simulation
Towards technological rules for designing innovation networks: a dynamic capabilities view.
Inter-organizational innovation networks provide opportunities to exploit complementary resources that reside beyond the boundary of the firm. The shifting locus of innovation and value creation away from the âsole firm as innovatorâ poses important questions about the nature of these resources and the capabilities needed to leverage them for competitive advantage. The purpose of this paper is to describe research into producing design-oriented knowledge, for configuring inter-organizational networks as a means of accessing such resources for innovation
Dynamic and Improvisational Capabilities in Small Defense Contractor Firms: An Investigation into the Role of IT Enabled Business Processes
In turbulent environments where the competitive landscape is shifting and uncertain, the dynamic capabilities by which firm managerâs, integrate, build, and reconfigure internal and external competences becomes the source of sustained competitive advantage. As they attempt to reconfigure their organizational competencies, firms are turning to Information Technology (IT) resources as an enabling resource. While the importance of dynamic capabilities has been widely recognized, in todayâs fast paced and ever changing business landscape, the need for improvisational capabilities has also been underscored. Whereas dynamic capabilities refer to the ability to respond to change through âplannedâ reconfiguration in moderately turbulent times, improvisational capabilities refer to the ability to respond to change through âspontaneousâ reconfiguration in highly turbulent times. This study begins to defragment dynamic and improvisational capability literature and demonstrate the need for these two complementary capabilities. This study also develops and offers an initial prescription for executing these complementary capabilities. This study highlights the significant differences in the execution of dynamic and improvisational capabilities at the sub-routine level. Lastly, this study offers valuable insight into how IT can enable both dynamic and improvisational capabilities
Clustering of Mobile Ad Hoc Networks: An Adaptive Broadcast Period Approach
Organization, scalability and routing have been identified as key problems
hindering viability and commercial success of mobile ad hoc networks.
Clustering of mobile nodes among separate domains has been proposed as an
efficient approach to address those issues. In this work, we introduce an
efficient distributed clustering algorithm that uses both location and energy
metrics for cluster formation. Our proposed solution mainly addresses cluster
stability, manageability and energy efficiency issues. Also, unlike existing
active clustering methods, our algorithm relieves the network from the
unnecessary burden of control messages broadcasting, especially for relatively
static network topologies. This is achieved through adapting broadcast period
according to mobile nodes mobility pattern. The efficiency, scalability and
competence of our algorithm against alternative approaches have been
demonstrated through simulation results.Comment: 7 pages, 9 figures; IEEE International Conference on Communications,
2006. ICC '0
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