Trouble parsing XML using PhP SimpleXMLElement

I am working with Google's provisioning API and I am using PhP's SimpleXmlElement to parse the XML response.

SimpleXmlElement isn't parsing the response correctly. Here's a sample.

<?php

$xml_response = <<<EOD
<?xml version='1.0' encoding='UTF-8'?>
<entry xmlns='http://www.w3.org/2005/Atom' xmlns:apps='http://schemas.google.com/apps/2006'>
  <id>https://apps-apis.google.com/a/feeds/alias/2.0/gethelp_example.com/helpdesk%40gethelp%5Fexample.com</id>
  <updated>2014-05-06T00:53:35.817Z</updated>
  <link rel='self' type='application/atom+xml' href='https://apps-apis.google.com/a/feeds/alias/2.0/gethelp_example.com/helpdesk%40gethelp%5Fexample.com'/>
  <link rel='edit' type='application/atom+xml' href='https://apps-apis.google.com/a/feeds/alias/2.0/gethelp_example.com/helpdesk%40gethelp%5Fexample.com'/>
  <apps:property name='userEmail' value='liz@example.com' />
  <apps:property name='aliasEmail' value='helpdesk@gethelp_example.com' />
</entry>
EOD;
$xml = new SimpleXmlElement($xml_response);
print_r($xml);

?>

Output:

SimpleXMLElement Object
(
  [id] => https://apps-apis.google.com/a/feeds/alias/2.0/gethelp_example.com/helpdesk%40gethelp%5Fexample.com
  [updated] => 2014-05-06T00:53:35.817Z
  [link] => Array
    (
      [0] => SimpleXMLElement Object
        (
          [@attributes] => Array
            (
              [rel] => self
              [type] => application/atom+xml
              [href] => https://apps-apis.google.com/a/feeds/alias/2.0/gethelp_example.com/helpdesk%40gethelp%5Fexample.com
            )
          )
      [1] => SimpleXMLElement Object
        (
          [@attributes] => Array
            (
              [rel] => edit
              [type] => application/atom+xml
              [href] => https://apps-apis.google.com/a/feeds/alias/2.0/gethelp_example.com/helpdesk%40gethelp%5Fexample.com
            )
        )
    )
)

SimpleXmlElement simply drops the two <apps:property …\> entries. I am using PhP 5.3.28. Are there additional options/parameters I can use with SimpleXmlElement to get this to work?

Details about Google's provisioning api can be found at https://developers.google.com/google-apps/provisioning/

Tip o' the hat to MackieeE and Raf for his comment on Parse XML with Namespace using SimpleXML which led me to the appropriately titled blog post @ http://blog.preinheimer.com/index.php?/archives/172-SimpleXML,-Namespaces-Hair-loss.html

Here's what I had to do:

<?php
$xml_response = <<<EOD
<?xml version='1.0' encoding='UTF-8'?>
<entry xmlns='http://www.w3.org/2005/Atom' xmlns:apps='http://schemas.google.com/apps/2006'>
  <id>https://apps-apis.google.com/a/feeds/alias/2.0/gethelp_example.com/helpdesk%40gethelp%5Fexample.com</id>
  <updated>2014-05-06T00:53:35.817Z</updated>
  <link rel='self' type='application/atom+xml' href='https://apps-apis.google.com/a/feeds/alias/2.0/gethelp_example.com/helpdesk%40gethelp%5Fexample.com'/>
  <link rel='edit' type='application/atom+xml' href='https://apps-apis.google.com/a/feeds/alias/2.0/gethelp_example.com/helpdesk%40gethelp%5Fexample.com'/>
  <apps:property name='userEmail' value='liz@example.com' />
  <apps:property name='aliasEmail' value='helpdesk@gethelp_example.com' />
</entry>
EOD;

$xml = new SimpleXmlElement($xml_response);
$alias_email = $xml->children('apps', true)->property[0]->attributes();
$user_email = $xml->children('apps', true)->property[1]->attributes();

$alias_email['value']; // gives you the aliasEmail value
$user_email['value']; // gives you the userEmail value
?>