title: Is it possible to receive out-of-order responses with HTTP?
body: <p><a href="http://www.ietf.org/rfc/rfc2616.txt" rel="noreferrer">Sec 8.1.2.2 Pipelining</a> says: </p>
  
  <blockquote>
    <p>"A server MUST send its responses to requests in the same order that the requests 
      were received". </p>
  </blockquote>
  
  <p>So, I thought, if I send out multiple AJAX requests from my browser, they will still be processed in the order in which they were received by the server.</p>
  
  <p>But then, I was reading this <a href="http://alexmaccaw.com/posts/async_ui" rel="noreferrer">post</a> from Alex Maccaw, where he states :</p>
  
  <blockquote>
    <p>"The last issue is with Ajax requests that get sent out in parallel. If a user creates
      a record, and then immediately updates the same record, two Ajax requests will be sent out 
      at the same time, a POST and a PUT. However, if the server processes the 'update' request 
      before the 'create' one, it'll freak out. It has no idea what record needs updating, as 
      the record hasn't been created yet.</p>
    
    <p>The solution to this is to pipeline Ajax requests, transmitting them serially. Spine 
     does this by default, queuing up POST, PUT and DELETE Ajax requests so they're sent one 
     at a time. The next request sent only after the previous one has returned successfully."</p>
  </blockquote>
  
  <p>So, how can I programmatically create the scenario that Alex Maccaw mentions ?</p>