Device MetaData in AWS IOT core

Question

Can we store Device/Thing MetaData in AWS IOT core ? 
We have iot things that we provision using fleet provisioning. These devices have metadata associated with it and other characteristics example battery health data which can change. What is a good practice to maintain this data ?
Should we use device shadows to maintain the battery health etc ? This data only flows from the device to aws and not vice versa , is the device shadow still a good place to hold the information ? 
How do we store the metadata associated with a thing ? We will need to retrieve this data using api's when needed.

Answer

Hi, to store data related to the device that changes over time you can use Thing Shadows. To report state you  will publish your data on `$aws/thing//shadow/update` in the following format

```
{
  "state": {
      "reported": {
           "battery": 0.40
      }
   }
}
```

To read the data you can either use the Thing Shadow REST API `GetThingShadow` [1] or subscribe to `$aws/thing//shadow/get/+` and publish a message on `$aws/thing//shadow/get`. [2]

[1] https://docs.aws.amazon.com/iot/latest/apireference/API_iotdata_GetThingShadow.html
[2] https://docs.aws.amazon.com/iot/latest/developerguide/device-shadow-mqtt.html

Device MetaData in AWS IOT core

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