The interaction with the payment gateway is described in the Implementation Guide Hosted Payment Page, 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.