Firebase Cloud Messaging Reliability

Question

We are building a messaging app and we are facing issues with messages delivery.

We are currently using socket.io to send messages on a running app but it's been proven highly unreliable. (Problem with slow network, late timeout, problem when app is in Doze mode,...)

We are thinking about switching to FCM but we have questions regarding reliability and speed. We don't want to change everything to see afterwards that it's not as reliable as wanted.

Have you already used FCM on a production app for every message ? Even when the app is running ?

Answer 1

It's hard to provide a concrete answer for this. Reliability wise, I would say FCM is pretty good.

Expected behavior is, if you successfully sent your payload to the FCM servers, it will send the message(s) as soon as feasible. When in doze, a low priority message is stored by FCM until the device is out of doze mode.

The documentation pretty much describes how the messages are handled in the FCM servers and all other related behaviors.