title: How to handle and delete "forgotten" uploaded files?
body: <p>I have a form to upload different kind of files.  I need to ask questions according to the uploaded file type.  For instance, if the file is a pdf, I need to ask the author.  If the file is an mp3, I need to ask the title of the song.</p>
  
  <p>So :</p>
  
  <ol>
  <li>the user uploads the file which is saved somewhere on the server;  </li>
  <li>the user answers the questions associated to the file type;  </li>
  <li>the user clicks the Save button (the answers are validated) to confirm everything.  </li>
  </ol>
  
  <p>Everything is fine so far.  Now what if the user never answer the questions or never click the Save Button?  Obviously I need to delete this "forgotten" file.  </p>
  
  <p>An idea I had was to store "unconfirmed" files in a kind of remote buffer cleaned on a regular basis.  Problem is managing appropriately this buffer and deciding when to clean it.</p>
  
  <p>Is there any best practice / existing solution for this?  What is the best approach?</p>