Is an EventSource (SSE) supposed to try to reconnect indefinitely?

Question

I\'m working on a project utilizing Server-Sent-Events and have just run into something interesting: connection loss is handled differently between Chrome and Firefox.

O

Answer 1

I read the standard the same way as you but, even if not, there are browser bugs to consider, network errors, servers that die but keep the socket open, etc. Therefore, I usually add a keep-alive on top of the re-connect that SSE provides.

On the client-side I do it with a couple of globals and a helper function:

var keepaliveSecs = 20;
var keepaliveTimer = null;

function gotActivity() {
  if (keepaliveTimer != null) {
    clearTimeout(keepaliveTimer);
  }
  keepaliveTimer = setTimeout(connect,keepaliveSecs * 1000);
}

Then I call gotActivity() at the top of connect(), and then every time I get a message. (connect() basically just does the call to new EventSource())

On the server-side, it can either spit out a timestamp (or something) every 15 seconds, on top of normal data flow, or use a timer itself and spit out a timestamp (or something) if the normal data flow goes quiet for 15 seconds.