---
title: Direct Device Integration API
parent: APIs
weight: 82
---

The hawkBit [update server](https://github.com/eclipse-hawkbit/hawkbit) provides REST resources which are consumed by
the device to retrieve software update tasks.
This API is based on HTTP standards and a polling mechanism.
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{{% note %}}
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.
{{% /note %}}

## State Machine Mapping

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.

The _DDI_ API allows the device to provide the following feedback messages:

 DDI `status.execution` type | handling by update server                                                                                                                                                                                                                 | Mapped ActionStatus type                              
-----------------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-------------------------------------------------------
 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) 
 DOWNLOAD                    | This can be used by the target to inform that it is downloading artifacts of the action.                                                                                                                                                  | DOWNLOAD                                              
 DOWNLOADED                  | This can be used by the target to inform that it has downloaded artifacts of the action.                                                                                                                                                  | DOWNLOADED                                            
 PROCEEDING                  | This can be used by the target to inform that it is working on the action.                                                                                                                                                                | RUNNING                                               
 SCHEDULED                   | This can be used by the target to inform that it scheduled on the action.                                                                                                                                                                 | RUNNING                                               
 RESUMED                     | This can be used by the target to inform that it continued to work on the action.                                                                                                                                                         | RUNNING                                               

## DDI APIs

<iframe style="padding-top: 20px;" width="100%" height="900px" frameborder="0" src="../../rest-api/ddi.html"></iframe>
