While the sociality of software agents drives toward the definition of institutions for multi agent systems, their autonomy requires that such institutions be ruled by appropriate norm mechanisms. Computational institutions represent useful abstractions. In this paper we show how computational institutions can be built on top of the RoleX infrastructure, a role-based system with interesting features for our aim. We achieve a twofold goal: on the one hand, we give concreteness to the institution abstractions; on the other hand we demonstrate the flexibility of the RoleX infrastructure.