ajax chatbox question.

[Isaac]

How often should I have a chatbox use ajax to check for new comments? Is every second too often?

[fliptw]

if once a second is too much you have a seriously bad connection.

[Isaac]

So twice a second won't bother people?

I might not have been clear. I'm wondering if people's machines might go slower because of an ajax module constantly calling out.

[fliptw]

as long as you don't let the chat box get too large it shouldn't be an issue. Keep each request to a maximum number of bytes and it should be good.

[Isaac]

gotchya! Thanks!

[Jeff250]

You could just have the client ask the server to poll every second for the next 30 seconds for you, returning either 1) the first newly discovered comment(s) or 2) nothing after the 30 second timeout, without the constant chatter between the client and server.

[Isaac]

I'm not too clear on that first line. It sounds like the server can forward info to the browser, with the client just waiting. We can do that? The browser can just sit there, requesting nothing, and expect to get data from the server when the server has something to send? Normally, I imagine we're pulling data from the server, normally. You're saying we can push data from the server?

Sorry, for not understanding. Thanks for your comment!

[Jeff250]

No, the client still makes a request, but the server just doesn't have to respond immediately. It can wait up to, say, 30 seconds before having to give its "no new comments" response. Otherwise, if it finds new comments before then, then all the better--it just immediately returns those comments instead of checking for new ones for the whole 30 seconds.

[Thenior]

I wonder how you'd do that though? Seems like default timeouts would get in the way.

[Jeff250]

I've found a good summary:
http://en.wikipedia.org/wiki/Comet_%28programming%29

The "long polling" approach is basically what I was describing.

I think something like 30 seconds should be safe, but timeouts might not even be a problem as long as you handle them properly.

[Isaac]

I'll be doing this during Christmas break.