Firebase：在所有设备上向用户发送推送通知

Question

I am building an app similar to Instagram. User uploads a post and other others can like it. When people like the post, I want the post author to get a push notification using FCM (Firebase Cloud Messaging).

My problem is that the refreshToken (that is generated using FirebaseInstanceId.getInstance().getToken(); ) is specific to the device. So if the same user logs into the app from a different device, I want to make sure I send a push notification to all the devices. So here is my proposed solution, I want to know if it's the right way to do it:

Every time user logs into a device, I store the refreshToken into the database and when I want to generate a push notification, I can iterate over all those refreshTokens and send a push notification to all those devices.

Is there a better way to accomplish this?

Note: I am aware of Device Group Messaging and I can't use that because I don't have an app server. And I don't want to do it on the client side because that requires the client to have a Google account.

Answer 1

Yes, the implementation is okay.

Every time user logs into a device, I store the refreshToken into the database.

This is actually not necessary to send the device push registration id (refreshToken in your case) each time user logs into your application from a device. You need to send the push registration id (ie refreshToken) from your device only when the device is not known to the server yet (ie new device).

Is there a better way to accomplish this?

I think no. This is the perfect way that you have implemented. However, we might always think of several optimization points like, tracking which devices are logged off, so that you do not need to send the push notification to that device any more. So in case of logging off from a device, send another invalidate refreshToken request to the server from that device, so that it does not get any further push notification. This is an improvement over the current implementation.