# A Trustworthy Communication Hub for Cyber-Physical Systems
## 6 Evaluation  
### Evaluation Process  
The evaluation of the trustworthy CPS communication hub was carried out in several steps in a laboratory environment targeting towards the final demonstration of energy flexibility and traffic accident cases of the M2 MGrids project [24]. The applied evaluation steps are shortly overviewed in the following, and a more detailed view is provided in the sections of this chapter. * _CPS hub with physical CPS asset devices_: Evaluation of the basic capabilities of the CPS hub, such as registering and operation of physical CPS asset devices with the virtual communication spaces. Increasing, step by step, the amount of owners and physical resources such as smart watches (Polar), hunting dog collars and specific servers (Tracker), street lamps and specific servers (Valopaa), and EEG measurement devices and specific servers (Bittium). Establishing trust relationship between owners, and increasing their amount. Application of publish/subscribe information sharing between physical resources owned by different stakeholders. * _CPS hub with services of automated dynamic microgrids_: Registration of the presence of the distributed resource components in the CPS hub: simulated electric vehicles simulated charging spots, charging manager, simulation model of the local distribution grid, user interface tool, visualizer tool, and energy market platform (Empower EMSP). Establishing a simple trust relationship between energy market platform and all the other components controlled by VTT. Enabling the resources to communicate with each other to collaborate to reach negotiated energy consumption/production flexibility in the day ahead/intraday energy market case. * _CPS hub with heterogeneous data planes_: Development and evaluation of the capabilities of the CPS hub to operate with heterogeneous data planes according to the needs of physical assets, the IoT platform, and/or enterprise zones. The evaluation considered application of MQTT, HTTP/CoAP, and OneM2M/ETSI M2M [30; 31; 32; 33], in order to evaluate the generic nature of the data plane negotiation capabilities of the CPS hub. * _CPS hub with streams-based M2M service platform in the energy flexibility case_: The capabilities of the CPS hub to operate in the energy flexibility case were evaluated in this evaluation step. The system included a new small scale external aggregator of VTT (FlexEntities), which aggregated a set of simulated distributed energy resources: electric vehicles and charging stations, as well as some buildings. These simulated DERs were controlled via the stream bridge of Nokia WWS by the higher-level aggregator service/local market. The evaluation included establishing the required streams towards the streams-based M2M service platform (Nokia WWS) for reaching the topic names for communication with the local market entity of Nokia WWS for the CPS hub via VTT stream proxy. Creation of the trust relationship with Nokia WWS system by applying a VTT stream proxy to simplify the test case. Evaluation of the interoperability of the CPS hub with Nokia WWS. In addition, evaluation of the scalability of the CPS hub by execution of multiple instances of the ADM simulation system owned by different stakeholders. * _CPS hub with external authorization service in the traffic accident case:_ The capabilities of CPS hub to operate with several heterogeneous stakeholders' systems and resources of multiple owners so that the security policies of the owners are considered in this evaluation step.