The Ditto Protocol furthermore covers two different communication channels to address different aspects of devices and their digital twins.
The first channel, twin, connects to the digital representation of a Thing. This Thing is managed with Ditto and its state and properties can be read and updated.
The second channel, live, routes a command/message towards an actual device. The handling and execution of a received command/message by a device (or a gateway which connects the device) is very specific to the solution and thus out of Ditto’s scope.
What Ditto however does, when routing live commands/messages, is an authorization check. Thus Ditto ensures that only authorized parties are able to send commands or messages.
Policy commands do not fit any of the above two categories as they are not directly related to a device. A Policy is not a twin of a device. Hence, the live channel cannot be used to address the device directly. Therefore Policy commands have no channel in the Ditto Protocol format specification.