Simplexml load file + request to xml

Read XML From a File

data.php

$xml = simplexml_load_file(http://www.domain.com/xml.php?id=999); /*full path of file*/
echo <pre>;
print_r($xml);
echo </pre>;

SimpleXMLElement + REQUEST

xml.php

header('Content-type: text/xml');
$xml_str='';
$xml_str.='<?xml version='1.0' encoding='UTF-8' ?>';
$xml_str.=<request>;
$xml_str.= <request_id>.$_REQUEST[id].</request_id>;
$xml_str.=</request>;
echo $xml_str;