android - Firebase push notification vs childAdd listener

Question

I'm working in a friend request module for mobile app base on Firebase so I'm considering to choose the way that notification is pushed.

Assume that userA request to be friend with userB. There're 2 ideas now:
- userA send request to a simple server then it will call FCM to send notification to userB.
- Make a service that listen to data changed in Firebase realtime database then userA will make change on that db and notification will be shown on userB device.

I think both are possible to implement but what is better, and why? Please give me some advice about this..

Thanks in advance.

Answer 1

Waitting for answers