34,333
edits
Changes
→Sending an Upstream Message from the Client
Similarly, the setCollapseKey() method may be used to identify a group of messages where only the most recent message is sent if multiple messages with the same key are waiting to be sent.
Once the message is sent it will arrive at the CCS where it will be passed to the app server. Any downstream messages sent to the client app will need to be handled within the onMessageReceived() method of the FirebaseMessagingService subclass as documented in the chapter entitled [[Integrating Firebase Cloud Messaging Support to an Android App]].
If the onMessageSent() and onMessageError() callback methods are also overridden in the FirebaseMessagingService subclass, these will be called to notify the app of the status of the message transmission:
