TwinMaker: using lambda to fetch data for non-timeSeries properties

Question

Hello!
I've been trying to use IoT RoboRunner + IoT TwinMaker + AWS Grafana to create a dashboard.
As one of the most basic things to show is a list of the current workers/robots.

Take the following `componentTypes`:
(parent, to be inherited from, to keep the lambda function common)
Ideally, the lambda function would be able to see the event, and the associated `telemetryAssetId`, and reply with an appropriate payload.
```json
{
  "componentTypeId": "com.example.lambda_reader",
  "workspaceId": "MyWorkspace",
  "functions": {
    "dataReader": {
      "implementedBy": {
        "lambda": {
          "arn": "arn:aws:lambda:us-east-1::function:RoboRunnerWorkerInfo"
        }
      }
    }
  },
  "propertyDefinitions": {
    "telemetryAssetId": {
      "dataType": {
        "type": "STRING"
      },
      "isExternalId": true,
      "isStoredExternally": false,
      "isTimeSeries": false,
      "isRequiredInEntity": true
    }
  }
}
```
and the child, which inherits from the above
```
{
    "componentTypeId": "com.example.myworkspace.worker_list",
    "extendsFrom": [
        "com.example.lambda_reader"
    ],
    "propertyDefinitions": {
        "telemetryAssetId": {
            "defaultValue" : { "stringValue": "WorkerList" }
        },
        "workerList": {
            "dataType": {
              "type": "LIST",
              "netstedType": {
                "type": "STRING"
              }
            },
            "isTimeSeries": false,
            "isStoredExternally": true
        }
    }
}
```
When adding these two `componentType`s, the latter shows up as abstract unless `isTimeSeries` is set to `true`. Is this intended behavior? Seems like I should be able to do this?
Any help is appreciated!

Accepted Answer

I was able to fetch non-timeseries properties by specifying a function under a different name than `dataReader`.

So, instead of 
```
  "functions": {
    "dataReader": {
      "implementedBy": {
        "lambda": {
          "arn": "arn:aws:lambda:us-east-1::function:RoboRunnerWorkerInfo"
        }
      }
    }
```
for non-timeseries properties, it should be 
```
  "functions": {
    "attributePropertyValueReaderByEntity": {
      "implementedBy": {
        "lambda": {
          "arn": "arn:aws:lambda:us-east-1::function:RoboRunnerWorkerInfo"
        }
      }
    }
```
Which is absolutely nowhere in the documentation. I arrived at it by sifting through github and finding https://github.com/aws-samples/aws-iot-twinmaker-samples/blob/main/src/modules/s3/component-types/s3_component_type.json

Answer

Hi, to explain little bit more into the detail, if a property is marked as `IsStoredExternally` means TwinMaker will only keep the property schema but not the value. So to access the property value you'll need to invoke the unified data access APIs with a defined connector.

For time-series property, you can use [GetPropertyValueHistory](https://docs.aws.amazon.com/iot-twinmaker/latest/apireference/API_GetPropertyValueHistory.html) API to access the property value, you need to define `dataReader` connector and while querying the property value in runtime, TwinMaker will forward the request to your connector to resolve it.

For non-time-series property, you can use [GetPropertyValue](https://docs.aws.amazon.com/iot-twinmaker/latest/apireference/API_GetPropertyValue.html) API to access, and as you already found out, you need to define `attributePropertyValueReaderByEntity` connector for that.

We'll continue polishing our documentation to make it clear. Let us know if you are interested in more details on the topic.

Best,

Answer

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TwinMaker: using lambda to fetch data for non-timeSeries properties

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