The design and analysis of cyber-physical systems bring many challenges, some of them resulting from the difficulty to express within the same formalism the interaction between discrete (cyber) and continuous (physical) processes. We propose in this work a component based description of cyber-physical systems. Components abstract from internal operations of both cyber and physical processes to only expose sequences of observable events. Algebraic operations are introduced to model interaction between components, and set the ground to build expressions for cyber-physical systems. The problem of coordinating multiple cyber components interacting through shared physical resources is finally presented.