title: Is it possible to notify a user of a new message in my Flutter chat app without Firestore or FCM?
body: <p>I currently have a Flutter application that has a chat feature. I've implemented it by writing standard CRUD operations. When a user sends a message, it posts it to the database. When a user navigates to a chat between two users, it makes an async REST call and grabs all of the messages in the chat. When you type in a message and hit send, it posts a message to the backend and persists it to the SQL DB.</p>
  
  <p>I currently have no way to "notify" a user of incoming messages. In order to see any new messages from the other user, I actually have to navigate away from the chat window and back to it. At a high level, this makes sense - the client has to request information from the server, so without any sort of event happening on the device, it wouldn't know to listen for a new message.</p>
  
  <p>I think that the only way to accomplish this is to use some form of push notifications, but is there a way to accomplish this without Firestore?
  Would I need to create a publish and subscribe service for my backend application?
  Is this only possible to do by utilizing push notifications in some way?</p>
  
  <p>And if it isn't, how would I go about learning how to do it?</p>
  
  <p>I apologize for how broad the question is, but I don't know how "real-time" chat works, and I'd like to get a deeper understanding on how I could implement it without using a pre-built tool. </p>