title: OWIN Stop Processing Based on Condition?
body: <p>I have the below code in my OWIN Startup class:</p>
  <pre><code>myiapbuilder.Map(&quot;/something/something&quot;, doit =&gt;
  {
      doit.Use&lt;pipepart1&gt;();
      doit.Use&lt;pipepart2&gt;();
      doit.Use&lt;piprpart3&gt;();
  });
  </code></pre>
  <p>If a condition occurs that I don't like in pipepart1, I would like to write a custom text/plain response to the caller within that Middleware, and do not fire pipepart2 or pipepart3. The BranchingPipelines sample on CodePlex shows lots of stuff, but not that.</p>
  <p>Is it possible to short-circut a flow or otherwise stop OWIN processing of Middleware based on an earlier Middleware evaluation?</p>