Como obtener el total de likes de comment y de compartidos de una pagina o una url con php


<?php
$source_url ='www.webdesignjc.com';
$url = "http://api.facebook.com/restserver.php?method=links.getStats&urls=".urlencode($source_url);
$xml = file_get_contents($url);
$xml = simplexml_load_string($xml);
$shares = $xml->link_stat->share_count;
$likes = $xml->link_stat->like_count;
$comments = $xml->link_stat->comment_count;
if($shares == '') { $fbcount = '0'; }
echo 'Compartidos'.$shares;
echo 'Me gusta'.$likes;
echo 'Comentarios'.$comments
?>  ------------------..............------------------