title: Is FCM suitable for a real time game backend?
body: <p>As Google has recently made major changes to Firebase, they've released a service called <a href="https://firebase.google.com/docs/cloud-messaging/" rel="nofollow">Firebase Cloud Messaging</a>, or FCM. I was wondering, could this work as a backend for a real time game between two players, as a replacement to a protocol like TCP or UDP? For example, a multiplayer game controlled by a game server with other player's position updates multiple times a second. I see that it can transfer 4kb of data per packet, and since it's hosted by Google I would think connection time would definitely be quick; however, Google doesn't advertise it as a game backend, but instead a messaging system suitable for applications like IM.</p>
  
  <p>Basically, what I'm asking is, compared to protocols like TCP and UDP, how does FCM compare in terms of:</p>
  
  <ul>
  <li>Reliability</li>
  <li>Speed</li>
  <li>Amount of traffic it can handle</li>
  <li>Is data sequential like TCP, or "random" order like UDP?</li>
  </ul>
  
  <p>And in the long run could it stand up to support constant communication between a game in server?</p>