A General Framework and Communication Protocol for the Real-Time Transmission of Interactive Media

In this paper we present a general framework for the real-time transmission ofinteractive media, i.e. media involving user interaction. Examples of interactive media are shared whiteboards, Java animations and VRML worlds. By identifying and supporting the common aspects of this media class the framework allows the development of generic services for network sessions involving the transmission of interactive media. Examples are mechanisms for late join and session recording. The proposed framework is based on the Real-Time Transport Protocol (RTP) which is widely used in the Internet for the real-time transmission of audio and video. Using the experience gained through the framework for audio and video, our work consists of three important parts: the definition of a protocol profile, the instantiation of this profile for specific media, and the development of generic services. The profile captures those aspects that are common to the class of interactive media. A single medium must instantiate this profile by providing media-specific information in the form of a payload type definition. Based on the profile, generic services can be developed for all interactive media. In this paper we focus on the description of the profile for the real-time transmission of interactive media. We then present the main ideas behind a generic recording service. Finally we show how multi-user VRML and distributed interactive Java animations can instantiate the profile

NetServ Framework Design and Implementation 1.0

Eyeball ISPs today are under-utilizing an important asset: edge routers. We present NetServ, a programmable node architecture aimed at turning edge routers into distributed service hosting platforms. This allows ISPs to allocate router resources to content publishers and application service pro\-vi\-ders motivated to deploy content and services at the network edge. This model provides important benefits over currently available solutions like CDN. Content and services can be brought closer to end users by dynamically installing and removing custom modules as needed throughout the network. Unlike previous programmable router proposals which focused on customizing features of a router, NetServ focuses on deploying content and services. All our design decisions reflect this change in focus. We set three main design goals: a wide-area deployment, a multi-user execution environment, and a clear economic benefit. We built a prototype using Linux, NSIS signaling, and the Java OSGi framework. We also implemented four prototype applications: ActiveCDN provides publisher-specific content distribution and processing; KeepAlive Responder and Media Relay reduce the infrastructure needs of telephony providers; and Overload Control makes it possible to deploy more flexible algorithms to handle excessive traffic

Krater & Co. frühzeitig vermeiden: Testmethoden bei Lackbenetzungsstörungen kennen und Prüfvorschriften einhalten

Ursachen von Beschichtungsfehlern können lackbenetzungsstörende Substanzen sein. Daher sollten industrielle Lackierbetriebe alle eingesetzten Stoffe und Bauteile prüfen

Steter Tropfen: Selektive Mehrfarbenbeschichtung: Oversprayfreies Lackauftragsverfahren birgt hohe Einsparpotenziale

Um eine höchstmögliche Flexibilität für individuelle Lackierungen zu erhalten und gleichzeitig Arbeitsschritte einzusparen, ist eine Technologie erforderlich, die einen randscharfen Lackauftrag ohne Maskierung mit vorhandenen Lacksystemen ermöglicht. Aktuell beschäftigen sich Wissenschaftler des Fraunhofer IPA mit dem Drop-on-Demand-Verfahren, das Bauteile selektiv randscharf und damit maskierungsfrei beschichtet

A New Paradigm for the Recording of Shared Whiteboard Streams

The number of video conferences conducted over the Internet has constantly increased during the last years. The need to archive the multimedia data streams of the conferences became apparent, and a number of tools accomplishing this task for audio and video streams were developed. In many video conferencing scenarios, shared whiteboards are used in addition to audio and video to transmit slides or to sketch ideas. However, none of the existing recording tools provides an efficient recording service for data streams of these tools. In this paper we present a new approach to the recording and playback of shared whiteboard media streams. We discuss generic design issues of a shared whiteboard recorder, and we present a novel algorithm that enables efficient random access to the recorded streams. We describe an implementation of our algorithms for the media streams of our digital lecture board (dlb)

Review The proteasome: a proteolytic nanomachine of cell regulation and waste disposal

The final destination of the majority of proteins that have to be selectively degraded in eukaryotic cells is the proteasome, a highly sophisticated nanomachine essential for life. 26S proteasomes select target proteins via their modification with polyubiquitin chains or, in rare cases, by the recognition of specific motifs. They are made up of different subcomplexes, a 20S core proteasome harboring the proteolytic active sites hidden within its barrel-like structure and two 19S caps that execute regulatory functions. Similar complexes equipped with PA28 regulators instead of 19S caps are a variation of this theme specialized for the production of antigenic peptides required in immune response. Structure analysis as well as extensive biochemical and genetic studies of the 26S proteasome and the ubiquitin system led to a basic model of substrate recognition and degradation. Recent work raised new concepts. Additional factors involved in substrate acquisition and delivery to the proteasome have been discovered. Moreover, first insights in the tasks of individual subunits or subcomplexes of the 19S caps in substrate recognition and binding as well as release and recycling of polyubiquitin tags have been obtained

A Light-Weight Repair Protocol for the Loss-Free Recording of MBone Sessions

With the increasing popularity of MBone conferences, the need arose to archive the multimedia streams of these conferences. Like all network applications, a conference recorder is subject to packet loss, which introduces gaps into recorded media streams. Such gaps degrade the playback quality of an archived media stream or even disable the correct playback. In this paper, we present a novel scheme for the loss-free recording of media streams. In contrast to existing systems that require the placement of recording caches within the network, our approach enables an end-to-end system design. We present a detailed protocol analysis that confirms the validity of our approach

Erfahrungen mit synchronen und asynchronen Lernszenarien an der Universität Mannheim

An der Universität Mannheim werden seit 1996 TeleTeaching-Projekte durchgeführt. Der Schwerpunkt liegt dabei in synchronen Lernszenarien, worunter wir eine zeitgleiche (Internet-) Übertragung einer Veranstaltung an verschiedene Orte verstehen. Die Audio- und Videoströme des Dozenten werden zugleich aufgezeichnet und als Bestandteil eines Computer-Based-Trainings zeitunabhängig für asynchrone Lernszenarien zur Verfügung gestellt. Die implementierten synchronen und asynchronen Lernszenarien werden seit 1998 im Verbundprojekt VIROR der ober-rheinischen Universitäten Freiburg, Heidelberg, Karlsruhe und Mannheim eingesetzt. Dieser Artikel beschreibt verschiedene Lernszenarien bei TeleVeranstaltungen, ihre Besonderheiten und spezifischen Anforderungen. Die zugrunde liegende Technologie wird kurz vorgestellt, einige selbst entwickelte Software Werkzeuge beschrieben und weitere, bislang nicht realisierte Anforderungen an die Technik formuliert. Das Hauptaugenmerk aber legen wir auf Erfahrungen, die wir in den nunmehr vier Jahren aktiven TeleTeachings gewonnen haben

A General Framework and Communication Protocol for the Transmission of Interactive Media with Real-Time Characteristics

In this paper we present a general framework for the transmission of interactive media with real-time characteristics, i.e. media involving user interaction. By identifying and supporting the common aspects of interactive media the framework allows the development of generic services for distributed, collaborative work involving the transmission of interactive media