Pushing message to users

[mikeallenbrown]

Is there a way to push a message to a user without the user needing to refresh the screen? ...meaning if I am about to restart the app server I'd like to somehow make a message appear in real time at the top of a user's browser saying "Server rebooting in 5 minutes, save your work" ....the program I work on uses the tabbed ui component.

I'm wondering if someone has done something like this.

-Mike

[TheSmitchell]

Re: Pushing message to users

Server don't send messages to clients. The communication is one-way in terms of client-server connection. You would need to get all your clients to setup open ports on their systems to listen for messages from your server if you wanted to send messages. And you'd have to configure a port on your server to do the sending. And setup server scripts and stuff. And possibly contact your host provider and ask them to open a port in the firewall to let you send messages to your clients...

But you can do what you need with some client-side scripts and a maintenance schedule.

Record your scheduled maintenance times in a file or in your database - wherever you feel most comfortable putting the data. Put it somewhere, though, that you can get the data & store it client-side:

1. When the page loads, get your maintenance schedule from the server (ajaxCallback).
2. If maintenance is soon - within 30 minutes? - issue a warning right away that the server is undergoing maintenance @ "Time of server maintenance" and that they need to save now less they drama
3. If maintenance is not soon, wait until however many min before scheduled maintenance and issue popup when it is soon (setTimeout(function, milliseconds))

The count down script that's been floating around for warning people that their session has expired or is going to expire soon could be modified to do this: http://msgboard.alphasoftware.com/al...l=1#post645868

Don't do something where you send an ajaxCallback to the server ever few minutes. DDoS and sessions that never expire lie down that path if done improperly.

[Clipper87]

Re: Pushing message to users

I use this javascript code to keep a session alive. You could do something similar with setInterval() to get a small file every so many minutes and if it loads then show a predefined message (alert()) for example to say that the server will be rebooted"

<!-- Keep session alive every 5 minutes -->
<script type="text/javascript">
setInterval(function() { var myelement = document.getElementById('myimg'); myelement.src = 'images/session.png?rand=' + Math.random(); }, 300000); 
</script>