Hi

AJAX n00b here with a JavaScript question.

I'm trying to write a JS applet that hits a URL on a server running Apache with mod_python. The idea of this applet is to retrieve incremental 'percentage complete' information about an operation running on the server.

I can get Apache/mod_python to return this information in real-time when the HTTP request is made, one update at a time, before returning. The problem is that XMLHttpRequest will not return until the page is completely loaded, so instead of getting incremental updates I simply get a long wait followed by a string of percentage values all at once.

Is there any way to get XMLHttpRequest to return or callback each time data is returned from the server (i.e. *before* the page has finished loading)? I had in mind something similar to a readline(), but don't know enough about JS to know what normal protocol is for this type of operation.

Cheers

That's your problem right there. Your mod_python page should only return a single value. You send an http request, and the mod_python script should only return the current status.

To get the effect of a progress/status bar, you need to put your loop in the javascript AJAX code. Have the javascript loop the AJAX request until an end-of-loop value is returned.

Doing AJAX by hand is a major PITA. You should take a look at one of the javascript frameworks like jquery or mootools. I haven't used mootools, but jquery makes AJAX a heck of a lot easier than trying to write it by hand and it also handles browser compatibility.

Have a look: http://docs.jquery.com/Ajax