Component Based Software Engineering is a good response to actual systems needs: flexibility and adaptability. In this context, design techniques based on software composition and verification techniques proving that the design properties are well implemented, are current and actively studied problematics. In this paper we present a composition design technique based on a formally defined theory: the whole-part relationship. We show, with an in-house verification framework, how to verify an implementation of composition properties. We illustrate our approach with a case study.