Open Distributed Systems are the dominating intellectual issue of the end of this century. Figuring out how to build those systems will become a central issue in distributed system research in the next future. Although CORBA seems to provide all the necessary support to construct those systems. It provides a very limited support to the evolution of requirements in those systems. The main problem is that the description of the elements from which systems are built, and the way in which they are composed are mixed into the application code. Making them difficult to understand, modify and customize. We think that a solution to