Hi all.

Ive just started to experiment with AJAX working with PHP and MYSQL to get data and display it and im looking to implement it into a shoutbox similar to the one here on the forums but i have a question...

i know how to use ajax and JS to refresh the contents of a DIV every few seconds r so and that essentially reloads the shoutbox content as the REFRESH button does up there ^^ on the shoutbox but i think it silly that it should update every few seconds even if theres no new activity so what im looking for is a way of letting my AJAX know when there is a new entry in the DB and then reloading the DIV to show it as a shout.

One way i just thought of is to use PHP to detect if a new entry has been made, if it has then i will echo out a variable containing the complete entry and if nothing has happened then i can echo out a variable that basically says "no" and have my AJAX detect that and not change the DIV. the downside is with all this AJAX loading the php file every few seconds server load wouldnt be good and it also has a habit of slowing down the browser and lagging it every now and then, this leads me to the next question..

Is there a way to notify my AJAX via php and SQL of a new entry in the database without loading the php page, so instead of AJAX contacting the PHP it works the other way around?

 

 

 

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In order to have the PHP script run, it has to be first called, of course. And in order for the AJAX to pick it up, it would have to be running at some kind of interval (of which the PHP script would be runned via cronjobs, whether or not there are visitors) to check the PHP script. This would not only put (extra) load on the server, it would also put load on the browser (however little it may be) of the user. On the version of my shoutbox that i'm working on (it has AJAX), i don't have it refresh at certain intervals, i just let the user click the "Refresh" link if they want to; the shoutbox will reload if they refresh the page or move to another page on my site. So i don't think what you want is possible: having PHP contact AJAX; for in the end it'll just be AJAX contacting PHP anyways and not the other way around.

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True, i didnt think of that...

I was wondering how the T17 shoutbox works, is that interval based? Eg a user shouts a message and so many seconds later it is updated?

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The way i've seen it work is it refreshes at an interval and it refreshes after the user submits a shout; the interval and shout times don't affect each other.

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Fair enough! It seemed to me as though it only updated as a shout was made but of course that was probably just because a user shouted before the update. Ah well i shall use my interval option then!

thanks

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