The intention of the payment API is to fetch payments upon a user action, often by means of a tender button on a point of sale system, as well as provide the ability to retrieve a historical list of all transactions that have been processed.
The payment API will return all relevant payments and does not provide an acknowledgement mechanism. Therefore, subsequent requests with the same parameters will return payments that were included in the previous request, and it is up to the client to ensure that these payments are applied correctly. If an acknowledgement mechanism is required, please use the preferred real-time payment notification solutions documented in the Payment Notifications section.
Payment polling should only be considered as last resort and may result in request throttling. The preferred alternative is to use the real-time payment notification solutions documented in the Payment Notifications section.
There are four distinct ways in which payments can be retrieved via the payment API.