Here is a function that will generate the UUID or global id

function generateUUID() {
	$proc="";
	$result="";
	$command="uuidgen";
	if ($proc = popen("($command)2>&1","r")) {
		while (!feof($proc)) $result .= fgets($proc, 1000);
		pclose($proc);
		return trim($result);
	}
}