Question

I have an application which uses an open JQuery Ajax connection to do long-polling/comet handling of updates.

Sometimes the browser and the server lose this connection (server crashes, network problems, etc, etc).

I would like the client to detect that the update has crashed and inform the user to refresh the page.

It originally seemed that I had 2 options:

• handle the ‘error’ condition in the JQuery ajax call
• handle the ‘complete’ condition in the JQuery ajax call

On testing, however, it seems that neither of these conditions are triggered when the server aborts the query.

How can I get my client to understand that the server has gone away?

Answer 1

Isn’t it possible to add a setInterval() function that runs every few seconds or minutes? That way you can trigger a script that checks whether the server is still up, and if not, reset the comet connection. (I don’t know what you use for the long-polling exactly though, so I don’t know if it’s possible to reset that connection without a page reload. If not, you can still display a message to the user).

So something like this:

var check_server = setInterval(function() {
  // run server-check-script...
  // if (offline) { // reset }
}, 60000);