title: Parse symfony xml config
body: <p>I have a symfony xml-config and need to parse it.</p>
  
  <pre><code>&lt;?xml version="1.0" encoding="UTF-8" ?&gt;
  &lt;container xmlns="http://symfony.com/schema/dic/services"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://symfony.com/schema/dic/services http://symfony.com/schema/dic/services/services-1.0.xsd"&gt;
  
  &lt;parameters&gt;
      &lt;parameter key="abcxyz" type="collection"&gt;
          &lt;parameter key="abc" type="collection"&gt;
              &lt;parameter key="a" type="string"&gt;a&lt;/parameter&gt;
              &lt;parameter key="b" type="string"&gt;b&lt;/parameter&gt;
              &lt;parameter key="c" type="constant"&gt;\My\Bundle\Type::TYPE_ABC&lt;/parameter&gt;
          &lt;/parameter&gt;
          &lt;parameter key="xyz" type="collection"&gt;
              &lt;parameter key="x" type="string"&gt;x&lt;/parameter&gt;
              &lt;parameter key="y" type="string"&gt;y&lt;/parameter&gt;
              &lt;parameter key="z" type="constant"&gt;\My\Bundle\Type::TYPE_XYZ&lt;/parameter&gt;
          &lt;/parameter&gt;
      &lt;/parameter&gt;
  &lt;/parameters&gt;
  &lt;/container&gt;
  </code></pre>
  
  <p>and I need to get the values "abc" and "xyz".
  I tried to get it with</p>
  
  <pre><code>$simpleXml = simplexml_load_string(file_get_contents(__DIR__ . '/myConfig.xml');
  var_dump($simpleXml-&gt;xpath('//parameters/parameter/parameter/@key'));
  </code></pre>
  
  <p>but the result is empty...</p>