title: How does client handles deferred result in long running rest calls
body: <p>I am learning rest with spring mvc/boot. I understand basic rest calls but i am having trouble understanding long running/non-blocking rest calls. </p>
  
  <p>I understand that with long running rest calls we start a separate thread and the server returns a DeferredResult object to client but how does a client is notified when the processing thread is completed ?</p>
  
  <p>Can someone provide me an example on how to handle this at clients end ? </p>
  
  <p>Also how the non-java clients can handle such request ?</p>