The hawkBit [update server](https://github.com/eclipse/hawkbit) provides REST resources which are consumed by the device to retrieve software update tasks.
In DDI the target is identified using a **controllerId**. Controller is used as a term for the actual service/client on the device. That allows users to have in some cases even multiple clients on the same target for different tasks, e.g. Firmware update and App management.
For historical reasons the DDI has a different state machine and status messages than the [Target State Machine](../../concepts/targetstate/) of the hawkBit update server.
This is kept in order to ensure that _DDI_ stays compatible for devices out there in the field. A future version "2" of _DDI_ might change that. _DDI_ also defines more states than the update server, e.g. multiple DDI states are currently mapped by the _DDI_ implementation to _RUNNING_ state. It is possible that in the future hawkBit will fully leverage these additional states.
CANCELED | This is send by the target as confirmation of a cancellation request by the update server. | CANCELED
REJECTED | This is send by the target in case an update of a cancellation is rejected, i.e. cannot be fulfilled at this point in time. Note: the target should send a CLOSED->ERROR if it believes it will not be able to proceed the action at all. | WARNING
CLOSED | Target completes the action either with `status.result.finished` SUCCESS or FAILURE as result. Note: DDI defines also a status NONE which will not be interpreted by the update server and handled like SUCCESS. | ERROR (DDI FAILURE) or FINISHED (DDI SUCCESS or NONE)
