I have observed the following behavior in Firefox 4 and Chrome 7:
If the server running the websocket daemon crashes, reboots, loses network connectivity, etc then the 'onclose' or 'onerror' events are not fired on the client-side. I would expect one of those events to be fired when the connection is broken for any reason.
If however the daemon is shutdown cleanly first, then the 'onclose' event is fired (as expected).
Why do the clients perceive the websocket connection as open when the daemon is not shutdown properly?
I want to rely on the expected behavior to inform the user that the server has become unavailable or that the client's internet connection has suffered a disruption.
TCP is like that. The most recent WebSockets standard draft (v76) has a clean shutdown message mechanism. But without that (or if it doesn't have a chance to be sent) you are relying on normal TCP socket cleanup which might take several minutes (or hours).
I would suggest adding some sort of signal handler/exit trap to the server so that when the server is killed/shutdown, a clean shutdown message is sent to all connected clients.
You could also add a heartbeat mechanism (ala TCP keep alive) to your application to detect when the other side goes away.