Un processus de médiation flexible dans un système d'informations distribué

We consider distributed informations systems that are open, dynamic and provide access to large numbers of distributed, heterogeneous and autonomous informations sources. Our problem consists in providing more pertinent informations to the users. Also, informations providers want to obtain requests corresponding as well as possible to their waitings. This part of mediation in general is few treated in classic mediations. So, we combine these two visions simultaneously in the flexible mediation process that we explain here. A mediator questions the providers that are able to reply to the request on their preferences expressed by bids. This system is not purely economic because providers qualities interfere in the calculation of the allocation. We consider that a request always must be treated if system has providers qualified for make it: a policy of requisition is so used in the mechanism. MOTS-CLÉS : Système d’information distribué, médiation, approche économique, réquisition, équité.