Imagine this scenario: You load an XML file (with configuration data) into the current session along with some custom methods to change data in the XML object in memory to , finally, save your changes.

But actually you can't use DOM Methods like dump_mem() after registering your DOM object in the current session.

Try this script:

-------------------------------------
<?php
session_start();

if (!isset($_SESSION['doc']))
  $_SESSION['doc'] = domxml_open_file('lalala.xml');

$_SESSION['doc']->dump_mem();
?>
<a href="<?=$_SERVER['SCRIPT_NAME']?>">click</a>
--------------------------------------

lalala.xml is a valid xml file.