Working with asset property notifications - AWS IoT SiteWise
Enabling asset property notificationsQuerying asset property notification messages

Working with asset property notifications

You can enable property notifications to publish asset data updates to AWS IoT Core, and then run queries on the your data. With asset property notifications, AWS IoT SiteWise provides an AWS CloudFormation template that you can use to export AWS IoT SiteWise data to Amazon S3.

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Enabling asset property notifications

By default, AWS IoT SiteWise doesn't publish property value updates. You can use the AWS IoT SiteWise console or API to enable notifications for each asset property.

Enabling asset property notifications (console)

You can use the AWS IoT SiteWise console to enable notifications for an asset property.

To enable or disable notifications for an asset property (console)

  1. Navigate to the AWS IoT SiteWise console.

  2. In the navigation pane, choose Assets.

  3. Choose the asset to enable a property's notifications.

    Tip

    You can choose the arrow icon to expand an asset hierarchy to find your asset.

    AWS IoT SiteWise "Assets" page screenshot with an asset hierarchy highlighted.

  4. Choose Edit.

  5. For the asset property's Notification status, choose ENABLED.

    AWS IoT SiteWise "Edit asset" page screenshot with "Notification status" highlighted.

    You can also choose DISABLED to disable notifications for the asset property.

  6. Choose Save.

Enabling asset property notifications (CLI)

You can use the AWS Command Line Interface (AWS CLI) to enable or disable notifications for an asset property.

You must know your asset's assetId and property's propertyId to complete this procedure. If you created an asset but don't know its assetId, use the ListAssets operation to view all of your assets for a specific model. Then, use the DescribeAsset operation to view your asset's properties including property IDs.

Use the UpdateAssetProperty operation to enable or disable notifications for an asset property. Specify the following parameters:

  • assetId – The asset's ID.

  • propertyId – The asset property's ID.

  • propertyNotificationState – The property value notification state: ENABLED or DISABLED.

  • propertyAlias – The alias of the property. Specify the property's existing alias when you update the notification state. If you omit this parameter, the property's existing alias is removed.

To enable or disable notifications for an asset property (CLI)

  1. Run the following command to retrieve the asset property's alias. Replace asset-id with the ID of the asset and property-id with the ID of the property.

    aws iotsitewise describe-asset-property \
  --asset-id asset-id \
  --property-id property-id

    The operation returns a response that contains the asset property's details in the following format. The property alias is in assetProperty.alias in the JSON object.

    {
  "assetId": "a1b2c3d4-5678-90ab-cdef-22222EXAMPLE",
  "assetName": "Wind Turbine 7",
  "assetModelId": "a1b2c3d4-5678-90ab-cdef-11111EXAMPLE",
  "assetProperty": {
    "id": "a1b2c3d4-5678-90ab-cdef-33333EXAMPLE",
    "name": "Wind Speed",
    "alias": "/company/windfarm/3/turbine/7/windspeed",
    "notification": {
      "topic": "$aws/sitewise/asset-models/a1b2c3d4-5678-90ab-cdef-11111EXAMPLE/assets/a1b2c3d4-5678-90ab-cdef-22222EXAMPLE/properties/a1b2c3d4-5678-90ab-cdef-33333EXAMPLE",
      "state": "DISABLED"
    },
    "dataType": "DOUBLE",
    "unit": "m/s",
    "type": {
      "measurement": {}
    }
  }
}

  2. Run the following command to enable notifications for the asset property. Replace property-alias with the property alias from the previous command's response, or omit --property-alias to update the property without an alias.

    aws iotsitewise update-asset-property \
  --asset-id asset-id \
  --property-id property-id \
  --property-notification-state ENABLED \
  --property-alias property-alias

    You can also pass --property-notification-state DISABLED to disable notifications for the asset property.

Querying asset property notification messages

AWS IoT SiteWise publishes asset property data updates to AWS IoT Core in the following format.

{
  "type": "PropertyValueUpdate",
  "payload": {
    "assetId": "String",
    "propertyId": "String",
    "values": [
      {
        "timestamp": {
          "timeInSeconds": Number,
          "offsetInNanos": Number
        },
        "quality": "String",
        "value": {
          "booleanValue": Boolean,
          "doubleValue": Number,
          "integerValue": Number,
          "stringValue": "String"
        }
      }
    ]
  }
}

Each structure in the values list is a timestamp-quality-value (TQV) structure.

  • The timestamp contains the current Unix epoch time in seconds with nanosecond offset.

  • The quality contains one of the following strings that indicate the quality of the data point:

    • GOOD – The data isn't affected by any issues.

    • BAD – The data is affected by an issue such as sensor failure.

    • UNCERTAIN – The data is affected by an issue such as sensor inaccuracy.

  • The value contains one of the following fields, depending on the type of the property:

    • booleanValue

    • doubleValue

    • integerValue

    • stringValue

To parse values out of the values array, you need to use complex nested object queries in your rules' SQL statements. For more information, see Nested object queries in the AWS IoT Developer Guide, or see the Publishing property value updates to Amazon DynamoDB tutorial for a specific example of parsing asset property notification messages.

Example query to extract the array of values

The following statement demonstrates how to query the array of updated property values for a specific double-type property on all assets with that property.

SELECT
  (SELECT VALUE (value.doubleValue) FROM payload.values) AS windspeed
FROM
  '$aws/sitewise/asset-models/a1b2c3d4-5678-90ab-cdef-11111EXAMPLE/assets/+/properties/a1b2c3d4-5678-90ab-cdef-33333EXAMPLE' 
WHERE
  type = 'PropertyValueUpdate'

The previous rule query statement outputs data in the following format.

{
  "windspeed": [
    26.32020195042838,
    26.282584572975477,
    26.352566977372508,
    26.283084346171442,
    26.571883739599322,
    26.60684140743005,
    26.628738636715045,
    26.273486932802125,
    26.436379105473964,
    26.600590095377303
  ]
}
Example query to extract a single value

The following statement demonstrates how to query the first value from the array of property values for a specific double-type property on all assets with that property.

SELECT
  get((SELECT VALUE (value.doubleValue) FROM payload.values), 0) AS windspeed
FROM
  '$aws/sitewise/asset-models/a1b2c3d4-5678-90ab-cdef-11111EXAMPLE/assets/+/properties/a1b2c3d4-5678-90ab-cdef-33333EXAMPLE' 
WHERE
  type = 'PropertyValueUpdate'

The previous rule query statement outputs data in the following format.

{
  "windspeed": 26.32020195042838
}
Important

This rule query statement ignores value updates other than the first in each batch. Each batch can contain up to 10 values. If you need to include the remaining values, you must set up a more complex solution to output asset property values to other services. For example, you can set up a rule with an AWS Lambda action to republish each value in the array to another topic, and set up another rule to query that topic and publish each value to the desired rule action.