- PayPal Instant Payment Notification is a call back system that will get initiated once a tranction is completed(eg: When ExpressCheckout completed successfully).
- you will receive the transaction related ipn variables on your call back url that you have specified in your request.
- You have to send this ipn variable back to PayPal system for verification, Upon verification PayPal will send a response string "VERIFIED" or "INVALID".
- PayPal will continuously resend this ipn, if a wrong ipn is sent.
- Ipn Listener script is provided for different language.
- Deploy IPN Listener script in Cloud environment or you can expose your server port using any third party LocalTunneling software , so that you can receive PayPal IPN call back.
- Make a PayPal api call (eg: DoDirect Payment request), setting the IpnNotificationUrl field of api request class to the url of deployed IPNListener script.
- You will receive ipn call back from PayPal.
- You can refer IPN guide at [https://www.x.com/developers/paypal/documentation-tools/ipn/integration-guide/IPNIntro]