...
this is illustrated in the following figure:
Black arrows indicates communication via the coordination layer and the direction of the arrows indicates the way the requested information is passed. The grey arrows indicates information flow outside the coordination layer.
Note that different status from pillars e.g. ”Water level” is implemented via alarms, i.e. if agreed the pillars will send alams if the "water level" grows to high. In this way it is up to the pillar to actively give status information when necessary.
...