In this paper we present a compositional reasoning to verify middleware-based software architecture descriptions. We consider a nowadays typical software system development, namely the development of a software application A on a middleware M. Our goal is to efficiently integrate verification techniques, like model checking, in the software life cycle in order to improve the overall software quality. The approach exploits the structure imposed on the system by the software architecture in order to develop an assume-guarantee methodology to reduce properties verification from global to local. We apply the methodology on a non-trivial case study namely the development of a Gnutella system on top of the SIENA event-notification middleware.