Shadows

Shadows provide an effective way to manage configurations for devices that are only intermittently online.

The device shadow contains reported and desired state objects of a device, referred to as reported and desired shadows.

The desired shadow contains configuration settings that the device should use and possibly also some optional custom settings. The device receives the desired shadow from the Tracking API as a response to the ingestion request.

The reported shadow contains the most recent position, sensor readings and settings that the device has sent. The reported shadow may also contain additional properties generated by the Tracking backend based on the device-ingested telemetry. Such properties are stored in system.computed property of the shadow.

In case the most recent telemetry did not contain all the possible data, the last known information will remain in the shadow. This means that you can see, for example, the last reported temperature or device firmware information in the reported shadow, even if the device did not send that information in the latest telemetry.

IMPORTANT Devices should not communicate directly with the shadows endpoints, but should instead send the telemetry to the ingestion endpoint, which updates the reported shadow and returns the desired shadow. Applications should only write to the desired shadow and only read from the reported shadow via the shadows endpoints.