How Does IPN work (for Website Payments Standard)?
“IPN” = “Instant Payment Notification” … part of PayPal’s™ “Website Payments Standard” service. • Customer places an order on your site • For payment, they are taken to a link on PayPal’s™ site, where they provide their information and pay for their order. • They click a link when finished (or wait 5 seconds) and return to your site. Meanwhile, between steps 2 and 3 above, PayPal’s™ server does this: • Paypal’s™ server sends a request to your website…which is waiting and listening for connections from PayPal™ to the /ipn_main_handler.php page. • Your server sits waiting and listening on ports 80 and 443. • When your server receives a request, it attempts to validate and be sure that the PayPal™ data provided matches the order details for which it is intended. • If validation passes, the customer’s order is released, and it lets the PayPal™ server know that you received their confirmation. This handshaking happens bidirectionally on ports 80 or 443, depending on how it was originate
