function setTimer() {
    setTimeout("startRequest()", 15000);    
}

function startRequest() {
    var oXmlHttp = createXMLHttpRequest();
    //var TopicID = document.getElementById("TopicID").value;
    //alert("xml opened");
    var ran_unrounded=Math.random()*10000000;
    var ran_number=Math.round(ran_unrounded);    
    oXmlHttp.open("get", "ajax_get_new_topics.aspx?&rand=" + ran_number, true);
    oXmlHttp.onreadystatechange = function () 
    {
        if (oXmlHttp.readyState == 4) {
            var RsltElem = document.getElementById("comments_span");
            //alert(oXmlHttp.responseText);
            if (oXmlHttp.responseText.length > 2)
            {
                var responsearray = oXmlHttp.responseText.split("|");
                if (responsearray[0] = "ok")
                {
                    var TopicCount = responsearray[1];
                    if (TopicCount > 0)
                    {
                        alert(TopicCount);
                        for (var i=0;i<TopicCount;i++)
                        {
                            alert(responsearray[2+i]);
                        }
                    }
                }
            }
        setTimer();
        }
    };
    oXmlHttp.send(null);
}