Display a UI screen on the terminal. After this operation, the terminal will display the defined screen.

Different screen types:

Type	Message	Selection	Dispense
Screen
Properties	• title • message • icon (optional) • buttons.<name>.label (optional)	• title • split (optional) • items.<name>.label (optional) • items.<name>.value (optional) • items.<name>.currency (optional)	• title • subtitle • background (optional)

The callbackUrl is called if a button is pressed, or an item is selected.

Callback notification

When a button is pressed or an item is selected, the callbackUrl will receive a POST request with a JSON body containing:

{
  "serialNumber": "P6X20141000001",   // Serial number of the terminal that triggered the UI notification
  "screenId": "confirm-order-dialog", // Screen id that triggered the UI notification.
  "response": "ok",                   // Response returned from the screen, usually the name of the button/item pressed.
}