In this paper we argue for UML-based metamodeling and pattern-based graph transformation techniques in computer-based systems development through an illustrative example from the domain of embedded systems. We present a tool that uses advanced graph-rewriting techniques to generate a schedule that satisfies hard real-time constraints for multi-modal systems. The input is a time-triggered system specification (using the Giotto language); the output is an instruction sequence for the E-machine: a virtual machine for hard real-time embedded systems.