function xml_request(url,callback)
{
	xmlHttp = get_xmlHttp();
    if(xmlHttp!=null){
	    xmlHttp.onreadystatechange=callback;
	    //	show the activity image
	    try{
	        //document.getElementById("loader").appendChild(img_busy);
	    }catch(e){
	    	if ( xmlHttp == null )
     			alert ( "Your browser does not support AJAX!" );
      		return;
	    }
	    //	init the request
	    xmlHttp.open("GET",url,true);
	    xmlHttp.send(null);
    }
}
function get_xmlHttp()
{
    var xmlHttp = null;
    try{
        // Firefox, Opera 8.0+, Safari
        xmlHttp=new XMLHttpRequest();
    }catch(e){
        // Internet Explorer
        try{
            xmlHttp = new ActiveXObject("Msxml2.XMLHTTP");
        }catch(e){
            xmlHttp = new ActiveXObject("Microsoft.XMLHTTP");
        }finally{
        	alert ( "Your browser does not support AJAX!" );
      		return;
      	}
    }
    return xmlHttp;
}