Detect if Firebase connection is lost/regained

Question

Is there a strategy that would work within the current Firebase offering to detect if the server connection is lost and/or regained?

I'm considering some offline contingencies for mobile devices and I would like a reliable means to determine when the Firebase data layer is available.

Answer 1

This is a commonly requested feature, and we just released an API update to let you do this!

var firebaseRef = new Firebase('http://INSTANCE.firebaseio.com'); firebaseRef.child('.info/connected').on('value', function(connectedSnap) {   if (connectedSnap.val() === true) {     /* we're connected! */   } else {     /* we're disconnected! */   } }); 

Full docs are available at https://firebase.google.com/docs/database/web/offline-capabilities.

Answer 2

Updated: For many presence-related features, it is useful for a client to know when it is online or offline. Firebase Realtime Database clients provide a special location at /.info/connected which is updated every time the client's connection state changes. Here is an example:

DatabaseReference connectedRef = FirebaseDatabase.getInstance().getReference(".info/connected"); connectedRef.addValueEventListener(new ValueEventListener() {   @Override   public void onDataChange(DataSnapshot snapshot) {     boolean connected = snapshot.getValue(Boolean.class);     if (connected) {       System.out.println("connected");     } else {       System.out.println("not connected");     }   }    @Override   public void onCancelled(DatabaseError error) {     System.err.println("Listener was cancelled");   } });