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.

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

Relevant content