IoT device/device profile tags in payload

Question

Is it possible to add IoT device tags & possible the devices profile tags in the message as it move across IoT Core/MQTT broker?

To be more specific, we have several tags for the device configured in the web console for this device. I'd like to add those tags like so:

   "DeviceTags":{
        "Foo":"Bar",
        "Another":"Tag"
    },
    "DeviceProfileTags":{
        "Profile":"Example",
        "Etc":"Etc"
    }

to the primary payload message before its sent off further downstream.

{
    "PayloadData": "<REDACTED>",
    "WirelessDeviceId": "<REDACTED>",
    "WirelessMetadata": {
        "LoRaWAN": {
            "ADR": true,
            "Bandwidth": 125,
            "ClassB": false,
            "CodeRate": "4/5",
            "DataRate": "3",
            "DevAddr": "<<REDACTED>>",
            "DevEui": "<REDACTED>",
            "FCnt": 2196,
            "FOptLen": 1,
            "FPort": 10,
            "Frequency": "904300000",
            "Gateways": [{
                "GatewayEui": "<REDACTED>",
                "Rssi": -31,
                "Snr": 7.75
            }],
            "MIC": "<<REDACTED>>",
            "MType": "UnconfirmedDataUp",
            "Major": "LoRaWANR1",
            "Modulation": "LORA",
            "PolarizationInversion": false,
            "SpreadingFactor": 7,
            "Timestamp": "2021-12-11T17:37:56Z"
        }
    }
}

I have a suspicion this is done in the IoT rule SQL but it isn't clear with the syntax or if its even possible.

Andrei S · Answer

Hi,

it's not possible to access device tags from IoT SQL statement, however you have several alternative options to achieve that:

1) Store the necessary key/value pairs per device in a DynamoDB table (instead of Device tsgs) and use get_dynamodb function of IoT SQL (see https://docs.aws.amazon.com/iot/latest/developerguide/iot-sql-functions.html) to enrich your message with this data in IoT rule. I recommend this option, as it causes the least operational overhead and scales very well with increasing number of the devices due to a scalability of DynamoDB (see https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/HowItWorks.ReadWriteCapacityMode.html).

2) Store the necessary key/value pairs per device in Device Shadow and use get_thing_shadow function of IoT SQL to enrich your message with this data in IoT rule. Knowing more about kind of data you want to store in key/value pairs would help to decide if this is a feasible option.

3) In case you decide against using DynamoDB or shadow, I suggest to store key/value pairs not in tags, but in Thing Attributes : https://docs.aws.amazon.com/iot/latest/apireference/API_ThingAttribute.html. Then you could build a Lambda function that reads the Thing Attributes  using DescribeThing (https://docs.aws.amazon.com/iot/latest/apireference/API_DescribeThing.html), and then use aws_lambda function of IoT SQL to call that Lambda function and enrich your message with tag data in IoT rule.   This option has two disadvantages: a/ potential scalability limits due to Transaction Per Second quotas on DescribeThing API call (350 Transactions per seconds, adjustable but not limitless) b/ Higher operational overhead as you need to develop and maintain an additional Lambda function. I recommend to consider options 1) and 2) before looking at 3)

Please let me know if that helps.

br , Andrei

IoT device/device profile tags in payload

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