title: Play 2 Scala feed a Websocket output Iteratee with several enumerators (PatchPannel?)
body: <p>I would like to feed a WebSocket output Iteratee with several enumerators progressively (for example I want to add a specific enumerator to the output Iteratee when I receive a specific event through the Websocket input iteratee).</p>
  
  <p>If I am right this is impossible if I just return <code>(in,out)</code> at the end of the Websocket function argument as out is already an immutable enumerator:</p>
  
  <pre class="lang-scala prettyprint-override"><code>WebSocket.using[JsValue] { request =&gt;
      val in: Iteratee[JsValue,Unit] = ...
      val out: Enumerator[JsValue] = ...
  
      (in, out)
  }
  </code></pre>
  
  <p>I think that Concurrent.PatchPannel is what I am looking for, but I can't manage to understand how to use it. Does anyone have an example of using Concurrent.PatchPannel? (if this is indeed what I am looking for).</p>
  
  <p>Thanks</p>