It should be possible to build an entire application environment through the composition of independently developed application components and tools (e.g. computational intensive, data and performance visualizers, and user interaction components). Such composition should require small modifications to each individual component. In this paper we describe our approach to the above problem, based on a interconnection model called PHIS. The PHIS model is based on a specialized form of process group which supports multicast, asynchronous message delivery and collective synchronization mechanisms. Such characteristics make the model suitable to support several forms of component interaction. PHIS prototypes support communication between applications which were written using different parallel programming models, for example a PVM-based component and a MPI-based component. In order to evaluate the functionalities provided by the PHIS model, as well as its flexibility, we describe one experiment where we have used PHIS to interconnect two already existent parallel genetic algorithm simulators, one written in PVM an the other in MPI.