Architecture de Négociation et d'Adaptation de Services Multimédia dans des Environnements Hétérogènes. (Multimedia Services Negotiation and Adaptation Architecture in Heterogeneous Environments)

In the last few years, new devices such as palm computers, smart phones, pocketPCs became common components of the computing infrastructure. These devices allowmultimedia information to be used on the Web at any time and anywhere. At the sametime, the content of the Web has known an important revolution. Today, the Webincludes continuous medias such as video, audio and 3D animations. The content iscreated in several formats with new functionalities. Usually, these formats are based onmany structural dimensions : logical, spatial, temporal and hypermedia.In order to ensure universal access to Web content, with respect to the constraintsof the current environment, it is necessary to design new systems that enable contentdelivery in different contexts. The objective of our work is to resolve the problemsrelated to content adaptation and negotiation based on the limitations of the targetdevices and the heterogeneous environment. We propose a flexible architecture calledNAC that includes different components for content negotiation and adaptation, andensures an efficient framework in which these components cooperate and exchangenegotiation-based information in order to reach the objective of the universal access.NAC allows several kinds of adaptations to be applied : structural adaptation,semantic adaptation and media resources adaptation. These adaptations satisfy dif-ferent contexts of the clients. We also propose a description model of the environmentcontext : UPS, a negotiation protocol and a rich collection of adaptation techniques.NAC concepts have contributed in W3C standardization efforts, in particular in theCC/PP framework and in work on Device Independence. This work includes perfor-mance evaluations in order to show the usability of our system in a practical framework.