This paper presents our work to propose an architecture of a middleware intended to mobile environments. We argue that Message Oriented Middleware (MOM) offers naturally an effective solution for some problems of this type of environment. In particular, it adopt a communication mode which deals better with frequent disconnections and terminal mobility. Unfortunately, current MOMs are characterized by a certain rigidity and a lack of context-awareness. We propose a definition and an architecture of an MOM based on the Jonathan framework. This architecture introduces more openness and adaptability to the middleware which are required in a mobile environment. We introduced the mechanisms of negotiation and resource monitoring, in order to have a communication support which is adapted to the current state of the environment.