Advanced Features Guide

Table Of Contents
Implementing the Instant Update API
How the Callback Works in the Express Checkout Flow
7
82 April 2012 Express Checkout Advanced Features Guide
How the Callback Works in the Express Checkout Flow
The Express Checkout flow is initiated on your shopping cart page when the buyer clicks
Checkout with PayPal.
Callback integrated into Express Checkout flow
From left to right, the following events are represented:
1. The Express Checkout flow is initiated on your shopping cart page when the buyer clicks
Checkout with PayPal.
2. In the call to the SetExpressCheckout API operation, you provide the URL where
PayPal can call your callback server, the flat-rate shipping options, and cart line-item
details.
3. You retrieve the token from the response.
4. You redirect the buyers browser to PayPal.
5. When the buyer first logs in to the PayPal site, PayPal obtains the buyers shipping address
and sends it in the callback request (shown as the red down arrow) to your callback server
at the specified URL.