In the context of a collaborative research project funded by the Canadian Institute for Telecommunications Research (CITR) 1 , we have developed a prototype system for remote access to News-on-Demand. This system allows the user to remotely access a multimedia database, containing news clips in the form of multimedia documents, over ATM and other types of networks. Special attention is given to quality of service (QoS) negotiation and adaptation. For instance, a given document may exist in different versions on different sites and possibly corresponding to different presentation qualities, such as video and audio quality, size of display and cost. A graphical interface is available for the user to select his preferences and provides the possibility of obtaining examples of specific quality features. The QoS negotiation and adaptation features allow for the selection of the best configuration for a given user request and for automatic adaptation in case of changes to the system parame...

In distributed multimedia systems, since multimedia objects are voluminous and unstructured, manipulation, transfer and visualization of such objects can require a lot of time and resources. It then becomes essential to prevent unsatisfactory information delivery. For that purpose, Quality of Service (QoS) management appears as an essential function supplied by distributed multimedia systems to provide the user the pertinent information with the required quality and efficient access. This function aims to control and guarantee the level of quality that the system is able to offer to the user. Providing this function requires the design and the implementation of a system database that stores and manages the metadata required for QoS management. We have created concepts and developed methods for managing the resources needed for QoS negotiation and adaptation in an adaptive distributed environment. The QoS manager we have prototyped is based on a metadata database which is in charge of managing all the QoS information required for QoS negotiation and adaptation. In this paper we follow an objectoriented approach to present metadata modeling for quality of service management in distributed multimedia systems. We identify the actors of the QoS negotiation protocol and present a conceptual model for QoS metadata associated with each of them. We prove the relevance of metadata for Quality of Service management while illustrating how QoS metadata is used during the different steps of the negotiation and adaptation protocol. 1.