Integration Guide

Table Of Contents
Express Checkout Integration Guide May 2010 17
Introducing Express Checkout
Express Checkout Building Blocks
1
Express Checkout API Operations
The PayPal API provides three API operations for Express Checkout, which sets up the
transaction, obtains information about the buyer, and handles the payment and completes the
transaction.
Express Checkout Command
PayPal provides a command that you use when redirecting your buyers browser to PayPal.
This command enables your buyer to log into PayPal to approve an Express Checkout
payment.
When you redirect your buyers browser to PayPal, you must specify the
_ExpressCheckout command for Express Checkout. You also specify the token that
identifies the transaction, which was returned by the SetExpressCheckout API operation.
NOTE: To enable PayPal to redirect back to your website, you must have already invoked the
SetExpressCheckout API operation, specifying URLs that PayPal uses to redirect
back to your site. PayPal redirects to the success URL when the buyer pays on PayPal;
otherwise, PayPal redirects to the cancel URL.
If the buyer approves the payment, PayPal redirects to the success URL with the following
information:
API Operation Description
SetExpressCheckout Sets up the Express Checkout transaction. You can specify information
to customize the look and feel of the PayPal site and the information it
displays. You must include the following information:
z URL to the page on your website that PayPal redirects to after the
buyer logs into PayPal and approves the payment successfully.
z URL to the page on your website that PayPal redirects to if the buyer
cancels.
z Total amount of the order or your best estimate of the total. It should
be as accurate as possible.
GetExpressCheckout Obtains information about the buyer from PayPal, including shipping
information.
DoExpressCheckoutPayment Completes the Express Checkout transaction, including the actual total
amount of the order.