function makeRequest(url) {
        var http_request = false;

        if (window.XMLHttpRequest) { // Mozilla, Safari, ...
            http_request = new XMLHttpRequest();
            if (http_request.overrideMimeType) {
                http_request.overrideMimeType('text/xml');
                // See note below about this line
            }
        } else if (window.ActiveXObject) { // IE
            try {
                http_request = new ActiveXObject("Msxml2.XMLHTTP");
            } catch (e) {
                try {
                    http_request = new ActiveXObject("Microsoft.XMLHTTP");
                } catch (e) {}
            }
        }

        if (!http_request) {
            alert('Giving up :( Cannot create an XMLHTTP instance');
            return false;
        }
        http_request.onreadystatechange = function() { makeOptions(http_request); };
   	http_request.open('GET', url, true);
        http_request.send(null);

    }

    function makeOptions(http_request) {

        if (http_request.readyState == 4) {
            if (http_request.status == 200) {
		
		var xmldoc = http_request.responseXML;
		var options_tot = xmldoc.getElementsByTagName('option').length;
		var html = '';
		
		for( var i = 0; i < options_tot; i++ ) {		    
		
		    var option_att = xmldoc.getElementsByTagName('option').item( i );
		    var prix = option_att.getAttribute( 'prix' );
		    var id_option = option_att.getAttribute( 'id' );

		    html += '<input type="checkbox" name="options[]" value="' + id_option + '"/> ' + option_att.firstChild.data  + ' (CHF ' + prix + ')<br />';
		}
		
		document.getElementById('options').innerHTML = html;
		
		
            } else {
                alert('There was a problem with the request.');
            }
        }
	
	else if(http_request.readyState == 1 ){
		document.getElementById('options').innerHTML = '<em>Chargement des options...</em>';
	}

    }