Approaches to make multiple sources interoperable were essentially investigated when one are able to resolve a priori the heterogeneity problems. This requires that a global schema must be elaborated or that mappings between local schemas must be established before any query can be posed. The object of this paper is to study to what extend a mediation approach can be envisaged when none of these features are a priori available. Our solution consists in matching a query with each of the local schema. We designed a first prototype which showed that the approach could be efficient. We propose in this paper a new more sophisticated prototype. A friendlier query language is available. The detection of matching is more successful. This kind of system can be installed on super-nodes in P2P networks in order to facilitate accesses to data by their semantics. It can thus contribute to the pervasive computing paradigm.