How does a Custom Payment Integration work in Lightspeed eCom?

Custom payment integrations for eCom are built and hosted in our external app framework.  The payment option is integrated with your site's eCom checkout to allow the customer to select the custom payment option in checkout, and if selected, when the user clicks the "Buy" button on the last page of eCom checkout, they are then forwarded to our system's payment page to complete payment.  Once payment is completed, the user is then sent back to their eCom order receipt. 

With some payment integrations, status of payment is not immediately known, in which case our system will continue to communicate with the payment gateway and will update eCom as to the order's payment status when the payment gateway informs us that the payment is completed.

Note: in this process, an eCom order is created before payment is made, but the order will be marked with the "Awaiting Payment" status until payment is completed.