title: How to store documents like google docs?
body: <p>I'm interested how does google docs store documents on server side because I need to create similar application.</p>
  
  <p>Does it use pure RTF/ODF files or own database?
  How do they make possible versioning and undo/redo feature?</p>
  
  <p>If anybody have knowing according this question please share with me.</p>