The interaction with the payment gateway is described in the Hosted Payment Page Implementation Guide , available in our online documentation archive.

The merchant website and the payment gateway interact by exchanging data.

To create a payment, this data is sent in an HTML form via the buyer’s browser.

At the end of the payment, the result is transmitted to the merchant website in two ways:

• automatically by means of notifications called Instant Notification URLs (also known as IPN or Instant Payment Notification).
• Via the browser when the buyer clicks the button to return to the merchant website.

To guarantee the security of the exchange, the data is signed with a key known only to the merchant and the payment gateway.