title: Why is DoExpressCheckoutPayment required for Paypal?
body: <p>I am trying to build a very simple paypal-backed shopping cart so users can purchase multiple items. I want paypal to handle all the payment details. I don't even want an order confirmation. I will manually check for order confirmation on paypal.</p>
  
  <p>At first I wanted to use "Website Payments Standard" because it seemed easy to create a form that will post to paypal and let paypal handle it from there. But no, this did not work because the "Website Payments Standard" buttons/form do not support submitting multiple items. I tried all sorts of key/value in my form, and it never worked.</p>
  
  <p>Then I tried Express Checkout using the instructions found <a href="http://www.techfounder.net/2011/04/23/breaking-down-the-paypal-api/" rel="nofollow noreferrer">here</a>. It largely worked, but as I understand it, after sending a SetExpressCheckout, you have to listen for a request from paypal and do a DoExpressCheckoutPayment to complete the transaction. <a href="https://stackoverflow.com/questions/6554998/why-is-the-paypal-sandbox-not-processing-payments">SO reference</a>.</p>
  
  <p>I find this a bit troublesome, because what if my server fails to receive the request from paypal and I never send a DoExpressCheckoutPayment? So a customer THINKS they have finished submitting an order, but the order was never received.</p>
  
  <p>Does anyone know of a way to skip this "confirmation" step? I find it unnecessary, and not sure why paypal requires it.</p>