Advanced Features Guide

Implementing the Instant Update API
Using the Callback
7
86 April 2012 Express Checkout Advanced Features Guide
The sample code below illustrates the callback response when you do not ship to the buyer’s
address.
METHOD=CallbackResponse
NO_SHIPPING_OPTION_DETAILS =1
When your callback server sends the previous response, the Review your information page has
these features:
 A message at the top of the page indicates that your business does not ship to this location.
 The shipping and handling section and the insurance section are dimmed.
 The buyer can change the shipping address.
 A new callback request is sent if the buyer changes the shipping address.
Using the Callback
To use the callback, you add parameter fields to SetExpressCheckout, provide PayPal a
URL for sending a callback request, and send PayPal the callback response in Name-Value
pair (NVP) format.
SetExpressCheckout
In the call to SetExpressCheckout, set the following parameters:
 Set the CALLBACK field to the URL where PayPal can call your callback server. PayPal
makes the HTTPS callback request each time either of the following events occur:
– The buyer changes their shipping address
– The buyer enters a new shipping address
 Provide values for the following required parameters:
– Provide values for the line-item details parameters, such as
L_PAYMENTREQUEST_
n_NAMEm, L_PAYMENTREQUEST_n_NUMBERm,
L_PAYMENTREQUEST_
n_DESCm, L_PAYMENTREQUEST_n_AMTm, and
L_PAYMENTREQUEST_
n_QTYm.
– Provide values for the flat-rate shipping options: n, L_SHIPPINGOPTIONISDEFAULTn,
L_SHIPPINGOPTIONNAMEn, and L_SHIPPINGOPTIONAMOUNTn.
–Set PAYMENTREQUEST_
n_SHIPPINGAMT to the amount set for the default flat-rate
shipping option.
If, for example, L_SHIPPINGOPTIONISDEFAULT0=true and
L_SHIPPINGOPTIONAMOUNT0=8.00, then
PAYMENTREQUEST_0_SHIPPINGAMT=8.00
–Set MAXAMT to the expected maximum total amount of the complete order.