Résumé : The article proposes to use an alternative approach to design and validation processes of loosely integrated distributed co-operating systems. The example of such a process constitutes the technological background of ITEA project PROTEUS. One of the major technical challenges of PROTEUS project consists in the development of a platform which would facilitate the integration, without major functional modifications, of existent software tools which originally are not designed to work in co-operation. The tools cannot be modified profoundly solely in view of their integration, only a supplementary layer of data interpretation can be introduced. The fact that the tools mustn't be modified in order to follow the integration requirements creates the need of a top level description. Commonly used UML[1] representation of overall tool service is not sufficient to provide distributed view on the co-operation scenarios. Most naturally the UML description is the best adapted when one attempts to obtain a semi automatic code generation. Yet, the UML description is not sufficient for formal verifications such as functional consistency proofs. In order to conciliate the divergent criteria it is proposed to use a higher level description language. This article intends to show the potential of knowledge management methodology used to build conceptual models of domains as a means for integration of UML representations of distributed systems.