title: Parse response to SetExpressCheckout for digital goods with AJAX (integrating PayPal Digital Goods for Express Checkout)?
body: <p>The documentation for PayPal is a little unclear.</p>
  
  <p>How are we supposed to parse the response to SetExpressCheckout for digital goods, which involves an iFrame overlaid on your web site? The digital goods experience allows the user to remain on your site, essentially, by displaying the PayPal payment pages in an overlay -- if I understand the documentation properly.</p>
  
  <p>However, we're confused about how you're supposed to communicate with the PayPal servers since there do not appear to be JSON responses provided by PayPal. Are we supposed to post a form and on the backend monitor for an IPN? Or can this all be done from the frontend via AJAX/JSON?</p>
  
  <p>Here is the PayPal page on digital goods and Express Checkout: <a href="https://cms.paypal.com/us/cgi-bin/?cmd=_render-content&amp;content_ID=developer/e_howto_api_IntroducingExpressCheckoutDG" rel="nofollow">https://cms.paypal.com/us/cgi-bin/?cmd=_render-content&amp;content_ID=developer/e_howto_api_IntroducingExpressCheckoutDG</a></p>
  
  <p>We're using Rails.</p>