function xml_text_node(elem,nam)
{
    try{
        return elem.getElementsByTagName(nam)[0].firstChild.nodeValue;
    }
    catch(e){
        return "";
    }
}


var AJAX = {
    XMLHttpFactories : [
        function () {return new XMLHttpRequest()},
        function () {return new ActiveXObject("Msxml2.XMLHTTP")},
        function () {return new ActiveXObject("Msxml3.XMLHTTP")},
        function () {return new ActiveXObject("Microsoft.XMLHTTP")}
    ],
    createXMLHTTPObject : function ()
    {
        xmlhttp = null;
        for (var i=0;i<AJAX.XMLHttpFactories.length;i++) {
            try {
                xmlhttp = AJAX.XMLHttpFactories[i]();
            }
            catch (e) {
                continue;
            }
            break;
        }
        return xmlhttp;
    },
    objectToURL : function (url,query_str_obj)
    {
           url_str=url + '?';
           for(property in query_str_obj)
               url_str+= property + "=" + encodeURIComponent( query_str_obj[property] ) + "&";
           return url_str;
    },
    execute : function (url, functionCallBack)
    {
        request = new Object();
        request.ajaxRequest = AJAX.createXMLHTTPObject();
        request.sendRequest = function()
        {
            if(request.ajaxRequest.readyState == 1)
            {   //never happen, cause we create a new request each time
                alert('error: still processing previous request');
                return;
            }

            request.ajaxRequest.open('get', url);
            request.ajaxRequest.onreadystatechange = function()
            {
                if(request.ajaxRequest.readyState == 4 && request.ajaxRequest.status == 200)
                {
                    //alert(request.ajaxobj.responseText);
                    functionCallBack(request.ajaxRequest);
                }
            }
            request.ajaxRequest.send(null);
        }
        request.sendRequest();
        return request;
    }
};