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device shadow

A copy of a device's state kept by the back end, so apps can read or change it even while the device is offline.

A device shadow is a service-side document holding a device's desired and reported state with a version number; apps write desired state, the device writes reported state, and the difference is delivered as a delta.

Examples

  • While a bench node is unplugged, the phone app writes {"fan": 70} into its shadow; when the node reconnects it reads the shadow and sets the fan.

See also

desired state reported state delta state
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