How would they work offline? That is like expecting your phone to ring if turned off.
You device code sends a notification request to the server, the server sends it to whatever Google stuff the developer mentioned above, that then works through said Google stuff to your phone… all this via the internet.
Now… if your Phone is offline, then it of course will not get the notification until it goes back on line (I think the Google stuff queues it up) .
But it seems the Server needs to be online at the time of the processed notification, else, well, nada…
notifications work even though the app is not operating in the backround
I am not sure if the App itself needs to be in background, I think it depends on the priority levels of the Notification widget. But as already alluded to, notifications use something in the Android’s OS as well… thus it is not the App per se that needs to be running as much as the phone needs to be on and online.
But even if the App is totally off, once it starts up, the notifications from the past start popping up … just like voicemail from missed calls when your phone is off.
And online connectivity with the Server is a key factor… as it is, well, an IoT server If it is NOT online, then nothing online related (email, notifications, webhook, API, etc.) will ever work properly.
Trains won’t work without track, planes won’t fly without sky, IoT won’t work without Internet…