## 1 Introduction  
There exist several definitions of Cyber-physical systems (CPSs) in the literature. For example, according to the International Conference on CPSs (ICPPS) ([[http://iccps.acm.org](http://iccps.acm.org)]([http://iccps.acm.org](http://iccps.acm.org))), CPSs are defined as the \"physical and engineered systems whose operations are monitored, coordinated, controlled, and integrated by computing and communication. In other words, CPSs are the systems with a coupling of the cyber aspects of computing and communications with the physical aspects of dynamics and engineering that must abide by the laws of physics\". According to [PERSON] and [PERSON] [1,2], CPSs are described as the systems that emphasise the link between computation and physical processes, thereby linking time, space and energy. The physical processes are monitored and controlled by computers that are embedded within these systems (also called embedded computers), and vice versa the computations are affected by the physical processes. This paper focuses on Industrial CPSs (ICPSs) that are commonly found in the automation and automotive domains, among others. Note that we overload the term CPS to refer to ICPSs. The radical transformation from an _embedded system_ to a CPS comes from the emphasis on integration of physical processes and a more broad networking aspect. Similar to CPSs, there exist several definitions of embedded systems and there is no agreed-upon definition of these systems, as stated by [PERSON] and [PERSON] [3]. According to [PERSON] and [PERSON] [4; 5], an embedded system performs a dedicated functionality by means of computer hardware, software and perhaps additional mechanical components, sensors and other parts. As a CPS can include one or more embedded systems, it is crucial to clearly define the boundary of embedded system (s) within the context of cyber-physical systems, which is often not clear. In this regard, an embedded system is defined as the system consisting of hardware, software and interfaces (ports) to receive/send sensor/actuator signals and network messages. The inputs (e.g., sensor signals) arriving at the input interface and the computed outputs (e.g., actuation signals) delivered to the output interface of the system are considered to be parts of the embedded system, as depicted in Figure 1. The sensors, actuators and physical processes that are sensed and controlled, respectively, are not considered to be parts of the embedded system. These entities, together with the embedded system and possibly communication with the rest of the eco-system constitute a CPS, as depicted in Figure 1. By an eco-system, we understand a set of communicating CPSs as well as their surrounding computation and communication infrastructure, i.e., realised via fog nodes, that can provide some control functionalities as well as a communication channel to Cloud. Thus, a CPS eco-system includes entities with which it interacts as well as the entities that are required by the communication infrastructure. To ease depicting of communication connections, we introduce a conceptual interface layer that captures all connections towards and from a CPS. Let us consider the example of the airbag system in a car. If the car crashes and its deceleration is fast enough, the crash sensors are triggered, which send crash signals to the computation unit that computes and produces the actuation signals to inflate the airbag. The sensor inputs, the computation unit (both hardware and software) and the actuation outputs are parts of the embedded system. The embedded system together with the crash sensors and the physical process (the environment) in which they are deployed, the airbag actuator and the airbag itself constitute the CPS.