From what I've seen, all backend duties are implemented in a server acting as another client to Firebase. Usually a Node server since Firebase has provided a JS SDK from the start, but I've seen implementations in all major languages.

You either implement some cron task in that server that periodically makes stuff with Firebase, or you use an endpoint in Firebase and use it a task queue for the server.

I'd would be great if someone with more experience could provide more info on how these backend duties are performed.

Edit: see this for more info https://groups.google.com/forum/#!topic/firebase-talk/r4d5H7...