Integration Guide

Express Checkout Integration Guide May 2010 37
4
Implementing the Simplest
Express Checkout Integration
The simplest Express Checkout integration requires the following PayPal API operations:
SetExpressCheckout, DoExpressCheckoutPayment, and optionally,
GetExpressCheckoutDetails.
z Setting Up the Express Checkout Transaction
z Obtaining Express Checkout Transaction Details
z Completing the Express Checkout Transaction
Setting Up the Express Checkout Transaction
To set up an Express Checkout transaction, you must invoke the SetExpressCheckout API
operation to provide sufficient information to initiate the payment flow and redirect to PayPal
if the operation was successful.
This example assumes that you have set up the mechanism you will use to communicate with
the PayPal server and have a PayPal business account with API credentials. It also assumes
that the payment action is a final sale.
When you set up an Express Checkout transaction, you specify values in the
SetExpressCheckout request and then call the API. The values you specify control the
PayPal page flow and the options available to you and your buyers. You should start by setting
up a standard Express Checkout transaction, which can be modified to include additional
options.
To set up the simplest standard Express Checkout transaction
1. Specify the amount of the transaction; include the currency if it is not in US dollars.
Specify the total amount of the transaction if it is known; otherwise, specify the subtotal.
Regardless of the specified currency, the format must have decimal point with exactly two
digits to the right and an optional thousands separator to the left, which must be a comma.
For example, EUR 2.000,00 must be specified as 2000.00 or 2,000.00. The specified amount
cannot exceed USD $10,000.00, regardless of the currency used.
AMT=amount
CURRENCYCODE=currencyID