title: How to send one to one message using Firebase Messaging
body: <p>I have been trying to read the official docs and guides about how to send message from one device to another. I have saved registration token of both devices in the Real Time Database, thus I have the registration token of another device. 
  I have tried the following way to send the message</p>
  
  <pre><code>RemoteMessage message = new RemoteMessage.Builder(getRegistrationToken())
                      .setMessageId(incrementIdAndGet())
                      .addData("message", "Hello")
                      .build();
  FirebaseMessaging.getInstance().send(message);
  </code></pre>
  
  <p>However this is not working. The other device doesn't receive any message. I am not even sure, if I can use upstream message sending to conduct device to device communication.  </p>
  
  <p><strong>PS:</strong> I just want to know if device-to-device messaging is possible using FCM? If yes, then is the code I used have some issue? If yes, then what is the correct way.</p>
  
  <p><strong>Update:</strong><br>
  My question was to ask whether device to device messaging without using any separate server other than firebase could messaging is possible or not, if yes than how, since there's no documentation about it. I do not understand what is left to explain here? Anyways I got the answer and will update it as an answer once the question gets reopened.</p>