PayPal Instant Payment Notification - 2009 Guide de l'utilisateur télécharger pdf (Page 11)

IPN Guide June, 2009 11

Introducing IPN

IPN Protocol and Architecture

The numbers in diagram correspond to the following steps:

1. The button action initiates a payment that completes on PayPal

2. PayPal sends your IPN listener a message that notifies you of the event

3. Your listener sends the complete unaltered message back to PayPal; the message must

contain the same fields in the same order and be encoded in the same way as the original

message

4. PayPal sends a single word back, which is either VERIFIED if the message originated with

PayPal or INVALID if there is any discrepancy with what was originally sent

Your IPN listener must implement the IPN authentication protocol (steps 2, 3, and 4 in this

diagram). After successfully completing the protocol, your back-office or administrative

process vets the contents of the message and responds appropriately. For example, if the

payment status for the transaction is “Completed,” your system can print a packing list or

email a password to your customer for downloading digital media.

IPN Messages Generated by PayPal APIs

PayPal generates an IPN message when you invoke an API operation, such as

DoExpressCheckoutPayment of DoDirectPayment during checkout. You can use this

notification to kick-off order fulfillment, enable digital media downloads, store information in

a customer relationship management (CRM) or accounting system, and so on.

The following diagram shows both the web flow and the IPN message authentication protocol:

1 2 ... 6 7 8 9 10 11 12 13 14 15 16 ... 59 60

Pas de commentaire

PayPal Instant Payment Notification - 2009 Guide de l'utilisateur Page 11