Terminology
Rapyd CloudLink app - An Android app that needs to be installed on the PAX terminal to handle communications with the Cloud Link API. The app is accessible through the MAXSTORE client that comes pre-installed on all PAX terminals.
DeviceToken - Once the Rapyd CloudLink app is installed on the terminal it provides a token, through the terminal activation process. The cash registry system must include this token in all requests intended for the given terminal.
CallbackUrl - A url that the Cloud Link API uses to deliver terminal status updates back to the cash registry system. Only used if the client has chosen to use the webhook communication implementation.
PollId - A UUID, created by the client and used for status polling.
TimeToLive - The time, in seconds, the cash registry system must wait before attempting a retry if a sale request is not reaching the terminal.
When sending a sale request to the Cloud Link API the caller will immediately receive a 202 Accepted response if the request is valid. That does not mean that the request has or ever will reach the terminal it is intended for. For the sake of simplicity the caller does not have to think about any cleanup in the case of unsuccessful delivery of the request to the terminal. He simply reports how long he wants to wait by using the TimeToLive parameter. If the SALE_RECEIVED status has not been reported within the given timeframe the Cloud Link API will reverse any action already taken and the caller is free to retry without the risk of any duplication.
CorrelationId - The correlationId is a value that the cash registry system adds to the initial sale request in order to perform message matching in the status update. The Cloud Link API will include the value in each status update.
EventType - Types of event that the terminal uses to report status updates. Types functionality can vary slightly depending on the method used for status updates. See here for webhooks and here for polling.