title: Web API 2 return OK response but continue processing in the background
body: <p>I have create an mvc web api 2 webhook for shopify:</p>
  
  <pre><code>public class ShopifyController : ApiController
  {
      // PUT: api/Afilliate/SaveOrder
      [ResponseType(typeof(string))]
      public IHttpActionResult WebHook(ShopifyOrder order)
      {
          // need to return 202 response otherwise webhook is deleted
          return Ok(ProcessOrder(order));
      }
  }
  </code></pre>
  
  <p>Where <code>ProcessOrder</code> loops through the order and saves the details to our internal database.</p>
  
  <p>However if the process takes too long then the webhook calls the api again as it thinks it has failed.  Is there any way to return the <code>ok</code> response first but then do the processing after?</p>
  
  <p>Kind of like when you return a redirect in an mvc controller and have the option of continuing with processing the rest of the action after the redirect.</p>
  
  <p>Please note that I will always need to return the ok response as Shopify in all it's wisdom has decided to delete the webhook if it fails 19 times (and processing too long is counted as a failure)</p>