# A Trustworthy Communication Hub for Cyber-Physical Systems
## 6 Evaluation
### CPS Hub with Physical CPS Assets  
The evaluation step focused on testing the basic capabilities of the CPS hub related to the registering and operation of physical CPS asset devices with the virtual communication spaces. Establishing trust relationship between owners. Application of publish/subscribe information sharing between physical resources owned by different stakeholders. The demonstration (the laboratory environment was represented for a wider audience in the ITEA M2 MGrids (m2 mgrids.erve.vtt.fi) booth in the digital innovation forum (DIF) event, see [[https://dif2017.org/](https://dif2017.org/)]([https://dif2017.org/](https://dif2017.org/)) as well as [[https://itea3.org/publication/download/itea-magazine-november-2017-28.pdf](https://itea3.org/publication/download/itea-magazine-november-2017-28.pdf)]([https://itea3.org/publication/download/itea-magazine-november-2017-28.pdf](https://itea3.org/publication/download/itea-magazine-november-2017-28.pdf))), included the following steps:  
* Configuring the communication spaces for the owners (Polar, Bittium, Tracker, and Valopaa) in the CPS hub, see also Figure 11.
* Connecting and authenticating the physical resources of the owners with the CPS hub/XMPP server over TLS connections. * Presence registration of the physical resources, smart watch of Polar, EEG measurement device of Bittium, dog collar of Tracker, and street illuminator of Valopaa into the CPS hub. * Visualizing the dynamic presence situation of physical resources in the CPS hub using the visualizer tool. * Negotiation of the trusted relationship (agreement) between Polar and Valopaa resources: smart watch and street illuminator. * Connecting and authenticating the physical resources of the owners, according to the trusted relationship for information sharing, with the CPS hub/MQTT broker. * Application of bluetooth LE low-power technology for delivery of heart rate information from low-power sensor to the Polar smart watch. Publishing the heart rate information measured and delivered via the Polar smart watch to the CPS hub using the CPS hub connector in the direct attachment method. * Subscribing the heart rate information of the Polar smart watch by street illuminator/intelligent lightning gateway of Valopaa in the CPS hub. * Checking the conditions for allowing the delivery of the subscribed heart rate information of Polar smart watch to the street lamp of Valopaa by the trust checker of the CPS hub. * Delivery of the heart rate information of the Polar smart watch to the street illuminator of Valopaa. * Adjusting the light intensity of street illuminator of Valopaa according to the measured heart rate information via the Polar smart watch. Application of the 868 MHz ISM radio technology for controlling intensity of light fixtures of the street illuminator by intelligent lightning gateway. The devices of the Valopaa and Polar of the demonstration (the laboratory environment was represented for a wider audience in the ITEA M2 MGrids booth in the digital innovation forum event) are shown in Figure 19. The lightning fixture (left) and the gray gateway box in the middle control the lightning according to the heart rate information published by Polar smart watches. The heart rates were simulated (white box, hand on the adjusting knob), so that it was possible to adjust the rates rapidly. A Polar M600 smart watch (white and black in the Figure 19) was applied for the exposing of heart rate information from the heart rate simulator and publishing it to the CPS hub via the gateway. A snapshot into the visualization of presence of physical resources and the trust relationships in the CPS hub is shown in Figure 20. The presence of the street illuminator and smart watch can be seen as green rectangles in the left side, and trust relationships of the owners in the right side of Figure 20.  
The evaluation indicates that the publish/subscribe type of information sharing seems to fit quite well for CPS/M2M type messaging, because in the experiment, there were few information elements in use.