description: >-
  A module that implements this interface should be able to:
  - store (add, remove, change) and retrieve predefined messages
  - show messages on a display

  When a display message contains a session id, the display message must be removed once the session has ended.
cmds:
  set_display_message:
    description: >-
      Command to set or replace a display message.
    arguments:
      request:
        description: >-
          Request to set a display message
        type: array
        items:
          description: The display messages to set
          type: object
          $ref: /display_message#/DisplayMessage
    result:
      description: >-
        Response to the set display message request.
      type: object
      $ref: /display_message#/SetDisplayMessageResponse
  get_display_messages:
    description: Command to get one or more display messages.
    arguments:
      request:
        description: The request for display messages
        type: object
        $ref: /display_message#/GetDisplayMessageRequest
    result:
      description: The display messages or an empty array if there are none
      type: object
      $ref: /display_message#/GetDisplayMessageResponse
  clear_display_message:
    description: Command to remove a display message
    arguments:
      request:
        description: The request to clear a message
        type: object
        $ref: /display_message#/ClearDisplayMessageRequest
    result:
      description: Response on the clear message request
      type: object
      $ref: /display_message#/ClearDisplayMessageResponse