title: Send HttpResponse(status=200) without "returning" - where to send?
body: <p>I am using the Slack Events API to record conversations with my slackbot.</p>
  
  <p>The Events API pushes the messages to my Django server with an HTTP POST.  Slack expects an HTTP 200 response within 3 seconds, or else they will re-POST the message.</p>
  
  <p>I want to store / process the Event, but I'm not sure that the processing will complete in 3 seconds.  I want to send the HTTP Status 200 back to Slack and then continue the process, but <strong>I don't know where to send it</strong>.  Usually, I <code>return HttpResponse(status=200)</code> and python manages the destination / sending.</p>
  
  <p>How do I identify the response URI?  Can I send the <code>HTTP Status 200</code> w/ <code>urllib2</code>?</p>
  
  <pre><code>import json
  import urllib2
  from django.http import HttpResponse
  
  def processEvent(event):
      # do some stuff that takes longer than 3 seconds
      return
  
  def incomingEvent(request):
      event = json.loads(request.body)
      url = request.?????
      req = urllib2.Request(url, HttpResponse(200))
      processEvent(event)
  </code></pre>