DeviceRequest/DeviceResponse Classes

As part of processing the POS request, the core is likely to need to display and/or print messages at the POS. This is done by creating a DeviceRequest object specifying the type of display required and invoking the deviceAccess() method on the host interface. The host will build a DeviceResponse object to return to the core to show the success/fail status of the operation along with all related data (for example keyed data entered by the operator).