The use of formalized knowledge in the description of contents process is a promising technique which already provides encouraging results. The thoughts focus on the role of meta-data and ontologies to contribute to the integration of information systems to build an open structure. In this article, we present an experiment on content description within the theme of federated identity. This description of the domain is based on the notion of ontology. We show that the use of an ontology and an effective juxtaposition of abstractions allow structured description giving greater autonomy and ease of scalability to a platform identity federation especially when it is based on the mobile agent cooperation