Most system-on-Chip (SoC) design methodologies promote the reuse of pre-designed (hardware, software, and functional) components. However, as these components are heterogeneous, their integration requires complex interface sub-systems. These sub-systems can also be constructed by assembling pre-designed basic interface components. Hence, SoC design and validation involves component composition techniques to create hardware, software, and functional interface sub-systems by assembling basic interface components. We propose a unified methodology for automatic component integration that allows designers to reuse pre-designed components effectively. We also present ROSES, a design flow that uses this methodology to generate hardware, software, and functional interface sub-systems automatically starting from a system-level architectural model.