The contribution of this paper is a Generic Communication Middleware (GCM) concept and architecture definition for application messaging in heterogeneous distributed computing environments. The GCM is targeted to facilitate the development of distributed applications into heterogeneous computing environments, with special attention given to applicability for both wireless and wired communication and variable capability devices. The requirements are gathered from the literature and initial prototype implementations. The GCM concept and architecture are presented in the paper. The novelty of the GCM middleware is that it provides both application and transport independent messaging system architecture that can be widely applied in different applications and services as middleware. Functional validation of the GCM concept and architecture is provided via prototypes overviewed and empirically analyzed in the paper.