How to send device to device messages using Firebase Cloud Messaging?

Question

After searching the docs I could not find any info on how to send device to device messages using FCM without the use of an external server.

For example, if I was cr

Answer 1

1) subscribe an identical topic name, for example:

• ClientA.subcribe("to/topic_users_channel")
• ClientB.subcribe("to/topic_users_channel")

2) send messages inside the application

GoogleFirebase : How-to send topic messages