XMLsocket (how/what ?)

Hi all, Im completely new with socket stuff and I allready did some
googling, but I cannot find an answer (that I understand).

What I try to do is make a RSS reader in flash that plays a sound when the RSS feed is changed.
In an older version I reloaded the xml via a little timer, but what I
understand about this socketthingy is that it keeps an open connection with the server/feed?

Am I correct that this socket parses data (or smth) as soon as the xml
changes ? If yes, why dont this work ? (it does after loading, but
not if the swf is running and the xml is changed)


var xmlTracker:XML = new XML();
xmlTracker.ignoreWhite = true;

xmlTracker.load("http://www.sitemasters.be/rss/xml/forum.xml");
xmlTracker.onData = function(data) {
    trace(data);
};

Can someone tell me if it really keeps an open connection, and if the data will be updated if the xml changes (and how ?)
TIA