System service?

[fabricedesre]

Some adapters, like the Hue one, need to notify the user of events, or to describe their status. For instance, the Hue adapter waits for the user to pair the bridge by tapping the bridge's button.

I can see two ways to add this functionality:

• each adapter will implement the appropriate channel, and the UI will aggregate all these values (they will have to share the same type to be easy to select).
• we create a "system service" that does the aggregation, so the UI only has to access a single service.