Distributed Objects: an approach to sharing multimedia information

1994

1997

Abstract In September 1993, the Canadian Institute for Telecommunications Research, in collaboration with the IBM Toronto Laboratory Centre for Advanced Studies, initiated a major project on broadband services. The goal of this major project is to provide the software technologies required for the development of distributed multimedia applications. Of particular interest are ���presentational ���applications where multimedia documents, stored in database servers, are retrieved by remote users over a broadband network.

Proceedings 26th Annual International Computer Software and Applications, 2002

Previously, we developed a method and a distributed platform for the re-engineering of applications by adding cooperation. The goal was to supply a way of communication based on the exchange of events, messages and shared data. Now, we propose to adapt this approach (method and platform) to distributed multimedia applications. These applications present the characteristic to be organized around the communication. So, we can consider them as composed of distributed components which have to collaborate. Because it is heavily interactive, such an application needs to adapt itself in real-time to the user and to the environment in which it runs. Our approach consists in breaking down the application into two levels : the first one reflects the users' point of view in terms of functionalities. The second one, reflects the way to achieve these functionalities in terms of quality of service. We propose to organize components into workgroups and subworkgroups corresponding to this two levels. The platform manages these groups and makes them evolve in real time. It also ensures the interoperability of components which cooperate in these groups.

Many multimedia presentation applications involve retrieval of objects from more than one collaborating server. For instance, we can consider distributed video servers where blocks of movies are distributed over a set of servers. Here, blocks of a movie from different video servers have to be retrieved and presented continuously without any gaps in the presentation. Such applications first need an estimate of the available network resources to each of the collaborating server in order to identify a schedule for retrieving the objects composing the presentation. A collaboratin server can suggest modifications of the retrieval sche % ule depending on its load. These modifications can potentially affect the retrieval schedule for other collaborating applications. In this paper, we propose an application sub-layer protocol, Resource Lock Commit Protocol (RLCP), for handling the negotiation and commitment of the resources required for a collaborative multimedia presentation application.

Lecture Notes in Computer Science, 1992

The eighth session was devoted to new abstractions for programming multimedia applications, and tools for specifying their execution and presentation. Programming abstractions for multimedia have not received much attention before, and are becoming increasingly important as multimedia applications grow in both complexity and number. In the first paper of this session, Simon Gibbs of the Universite de Geneve together with Christian Breiteneder, Laurant Dami, Vicki de Mey, and Dennis Tsichritzis presented "A Programming Environment for Multimedia Applications." The environment consists of two levels: A systems level environment for handling synchronization between media, and a user level environment for specifying media presentation. The systems level environment encapsulates hardware dependencies, and enforces synchronization between media objects which can be sources, sinks, or filters, depending on whether they produce or consume media values, or both. The user level environment provides an object-oriented framework in which, application designers can specify in a scripting language the composition, presentation, and communication among media objects. Sequences of presentations constitute activities, and multiple activities can be executed sequentially, concurrently, or periodically. The second paper was by Gerold Blakowski, Jens Htibel, and Ulrike Langrehr of the University of Karlsruhe ("Tools for Specifying and Executing Synchronized Multimedia Presentations"). Gerold presented tools for managing synchronized presentation of multimedia in distributed heterogeneous environments. Users can define objects of type Medialnformation, Presentation, or Transport. A graphical synchronization editor helps users to specify both intra-object and interobject synchronization using a context-free grammar based description language. From these synchronization specifications, the synchronizer constructs a presentation thread of all the media objects, using which it enforces the synchronization relationships. The synchronizer also takes actions such as pause/wait or acceleration/skip in order to speed up a lagging media presentation or slow down a leading media presentation. The entire media synchronization management system including the graphical editor is being designed as part of the MODE project in the NESTOR authoringlearning environment being developed at the Universities of Karlsruhe and Kaiserslautern.

Decision Support Systems, 1999

Building CSCW applications is still a complex task. This paper presents a software framework based on objects for building collaborative applications mainly on top of the Web. The 10 objects of the framework are box, boxObject, enÕironment, user, role, session, broadcast, Õiew, boxObjectType and floorControl. We argue that these objects can be combined to produce a great number of collaborative applications. The main aspects in the framework and objects design are discussed. Examples of applications that were developed using the framework are also shown. q 1999 Elsevier Science B.V. All rights reserved.

1999

This paper investigates the use of object-oriented techniques for the specification and design of distributed multimedia applications (DMAs). DMAs are a class of software applications with a range of strong-often conflicting-requirements of dynamicity, interactivity, real-time synchronized processing of several media types, network distribution, high-performance, fault-tolerance, load balancing and security. The development of complex DMAs can benefit from the adoption of object design methods and distributed object implementation technologies. The paper describes the use of two modeling approaches, based on the standard UML modeling language, and on the TRIO formal specification language, respectively. The problem of defining steps to move from the UML or TRIO specification to a CORBA IDL implementation is addressed. An experimental distributed video-on-demand system is used throughout the paper as a case study

CLEI Electronic Journal, 1999

Today's distributed applications need to interoperate across different administrative domains, handle multiple types of media, and execute on different computing platforms with different processing and networking capabilities. These demands pose several challenges to the application designer. Issues such as interoperability, real-time communication, security and performance must be properly addressed. This paper addresses the issue of multimedia communication across packet switching networks such as the Internet. The paper describes the design, implementation and evaluation of a generic communication infrastructure based on the Reference Model of Open Distributed Processing (RM-ODP). The infrastructure's components are implemented as distributed objects. The implementation can be easily integrated into cooperative applications such as teleconference and telemedicine; serve as a basis for implementing stream interfaces as proposed by the Object Management Group (OMG); or stil...

1995

Abstract An open architecture for the distribution of networked multimedia was designed, with the goal being to to allow interoperability between diverse networked multimedia distribution systems built for a range of applications. The approach taken was to use existing standards and technologies as much as possible, especially the World Wide Web and the Internet.

1991

In this paper we describe ongoing work in protocol support for distributed multimedia applications. This work concerns the provision of suitable transport mechanisms to convey multimedia information (text, and digital voice and video) between multimedia workstations in a distributed system. There are two parts to the Lancaster multimedia work. First, we have developed an abstract model for multimedia communications that is based on the use of streams; and second, we have built an experimental system on which to test the implementation of protocols based on this model. This paper reports on both aspects of the Lancaster work, describing the results so far and identifying areas to be investigated further.

1994

Abstract Existing models and systems which integrate multimedia documents and collaborative distributed editing have a major drawback. They do not support media specific types of collaboration and distribution in a satisfactory way. We present a framework model for collaborative multimedia editing in which each media type can use its own type of collaboration and distribution.

Proceedings of the second ACM …, 1994

% ?he Distributed Audio Video Environment provides object reusability, supports interopera bility and network independence, and provides a simple conceptual model for application development.

2017

The purpose of this work is to examine and exploit the potential of the coordination paradigm to act as the main communication and synchronization mechanism between components forming a distributed multimedia environment and exhibiting real-time properties. Towards this purpose, we have developed a mechanism for coordinating the distributed execution of components, as these are defined by the Multimedia System Services Architecture (MSSA). Our coordination environment uses the control-driven approach to coordination, namely the model IWIM and the associated language Manifold. In the process we show how Manifold can be used to realize object communication and synchronization of MSSA components and we present a methodology of combining a software architecture such as MSSA with a coordination language such as Manifold. We illustrate our approach by means of a suitable example.

Lecture Notes in Computer Science, 1994

In this paper we focus on some implementation issues related to the development of an experimental Object-Oriented Multimedia Information System for an Office Environment. Multimedia objects in our system are created, structured, filed, retrieved and browsed. In this article we give a quick introduction of the whole system and a brief synthesis of the experience on using the OMT methodology.

Multimedia Tools and Applications, 2003

Many multimedia presentation applications involve retrieval of objects from more than one collaborating server. Presentations of objects from different collaborating servers might be interdependent. For instance, we can consider distributed video servers where blocks of movies are distributed over a set of servers. Here, blocks of a movie from different video servers have to be retrieved and presented continuously without any gaps in the presentation. Such applications first need an estimate of the available network resources to each of the collaborating server in order to identify a schedule for retrieving the objects composing the presentation. A collaborating server can suggest modifications of the retrieval schedule depending on its load. These modifications can potentially affect the retrieval schedule for other collaborating applications. Hence, a sequence of negotiations have to be carried out with the collaborating servers in order to commit for a retrieval schedule of the objects composing the multimedia presentation. In this paper, we propose an application sub-layer protocol, Resource Lock Commit Protocol (RLCP), for handling the negotiation and commitment of the resources required for a collaborative multimedia presentation application.