title: PHP -> How can I check if a XML is empty
body: <p>I get simple xml content from a request after a certain ID. But sometimes an ID isn't anymore available and the XML is empty.</p>
  
  <p>How can I check with PHP if a xml is empty?</p>
  
  <p>If someone has an idea I would appreciate if he could help me.</p>
  
  <p>Thanks in advance.</p>
  
  <p>Marco</p>