Components are increasingly used to create complex and distributed systems and applications. They are often viewed as simple servers, which limits their capacity for collective action. In this paper, we propose a method to simplify their assembly and their potential re-usability. We use the notion of dependency and contract between components to explicitly design an entity that guarantee the correctness of the built system. We introduce split contracts and delegations of properties to check, both at conception and execution time, the correctness of the built system. Our solution increases the independence of the participating entities by isolating the core components and transferring the aggregation into specific "glue" components.