2012
Table Of Contents
- Instant Payment Notification Guide
- Contents
- Preface
- Introducing IPN
- Implementing an IPN Listener
- Identifying Your IPN Listener to PayPal
- IPN Testing
- IPN Operations on PayPal
- Using Fraud Management Filters With IPN
- IPN Variable Reference
- IPN Transaction Types
- Transaction and Notification-Related Variables
- Buyer Information Variables
- Payment Information Variables
- Auction Variables
- Mass Pay Variables
- Recurring Payments Variables
- Subscription Variables
- Dispute Resolution Variables
- Pay Message Variables
- Preapproval Message Variables
- Adaptive Accounts IPN Messages
- Payment Review Using Notifications
- Revision History
IPN Guide July 10, 2012 13
Introducing IPN
IPN Protocol and Architecture
IPN Messages Generated by a Back-Office Procedure
PayPal generates an IPN message when you perform actions that invoke the PayPal API,
regardless of whether it is from your website or from a back-office or administrative
procedure. You can use this notification to trigger an email to your customer, store information
in a CRM or accounting system, and so on.
The following diagram shows both an administrative web flow and the IPN message
authentication protocol:
The numbers in diagram correspond to the following steps:
1. Your back-office or administrative process invokes a PayPal API operation; for example, it
could invoke the RefundTransaction API operation when your employee issues a
refund.
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 implements the IPN authentication protocol (steps 2, 3, and 4 in this
diagram). After successfully completing the protocol, your listener or back-office or
administrative process vets the contents of the message and responds appropriately. For
example, your system can notify the customer of the refund by email.