function getDescription(channelId) {
    var url = '/test?channelId=' + channelId;
    if (window.XMLHttpRequest) {
        req = new XMLHttpRequest();
    } else if (window.ActiveXObject) {
        req = new ActiveXObject("Microsoft.XMLHTTP");
    }
    req.onreadystatechange = processRequest;
    req.open("GET", url, true);
    req.send(null);
}

function processRequest() {
    if (req.readyState == 4) {
        if (req.status == 200) {
          parseMessages();
        } else {
          alert ( "Not able to retrieve description" );
				}
    }
}

function parseMessages() {
	response  = req.responseXML.documentElement;
	itemDescription = response.getElementsByTagName('description')[0].firstChild.data;
	alert ( itemDescription );
}