In case you are using redirection to integrate with the payment gateway, there might be a transaction for which the response message will not reach your system. That might occur due to connection loss or browser termination from the user.

The most common solution to that issue is the use of a service, called background confirmation.

With that service, an exact copy of the initial response message is sent, within 120 seconds, from the payment gateway directly to your server. That is a server to server communication, without the risks of browser’s interference.

By default, the copy is sent to the same URL (confirm/cancel URL of the request) the initial response message was posted to, however there is also the option to set an alternative URL to receive all background confirmation requests.

Background confirmation is only sent once and there is no repeats if any error is returned from the merchant’s server.

Background confirmation does not somehow alter the already implemented integration, so there is no extra manual for that. If you wish to review the response message parameters, you may check the respective redirect documentation at https://developer.cardlink.gr/api-product/redirect/.

Given that it is sent in every completed transaction (in every transaction a response message is initially sent), your system needs to be able to handle multiple responses for each order for the (most common) cases where the initial response message has successfully reached your server.

One way you could distinguish the background confirmation from the initial response message is the header “Modirum VPOS”.

The various statuses of a transaction that can be returned through background confirmation (as in the initial response message) can be found at https://developer.cardlink.gr/documentation_categories/response-codes/#VPOS-Transaction-Statuses.