Cyber Physical Systems (CPSs) are the next computing revolution and the new generation of complex System of Systems (SoSs). CPSs are complex and ubiquitous embedded devices coupled with global integration respecting Moore's Law. Therefore, to fit with their new characteristics, we are facing several challenges, such as the proliferation and the integration of these systems into scalable environment. A main concern of embedded real-time systems is safety. For such safety-critical systems, not only correct results count, but also the runtime duration for producing them. To ensure the dependability of such systems, which is not a local property of the system, but a global system property, the SoS safety has to be assessed, evaluated and checked according to its specific runtime context. In an attempt to address the challenges, we propose two domain specific languages for modeling the system architecture and the dynamic behaviour of heterogenous systems and their interactions. This paper shows how to develop an approach of real-time system design based on an extension of Milner's Calculus Communicating Systems since languages which are based on process algebra provide suitable features to formalise components communications.