IoT Limitation

• IoT Limitation
  • Objective
  • Targets / Requirements
  • Final Working Solution
  • Learning Points
  • Test

Objective

To create a Pub Sub Model to overcome limitations of AWS IoT

Targets / Requirements

1. Users will subscribe to many different topics
2. Published message should reach to authorized Users only

Final Working Solution

1. Created a DynamoDB Table named `Subscriptions` with `topic` as primary key
2. Created a Lambda to populate this table with key pair of `topic` and `users` array
3. Created another Lambda to re-publish a published message to all authorized users only
4. Created a IoT Rule that will trigger the re-publishing lambda when a message is published

Learning Points

1. Package : `aws-iot-device-sdk` can't be used with lambda as I faced issues while making code synchronous
2. Below mentioned method worked just by using default aws library functions

```js
    var iotdata = new AWS.IotData({
        endpoint: await getIoTEndpoint()
    });
    async function getIoTEndpoint() {
        var params = {
            endpointType: 'iot:Data-ATS'
        };

        const iot = new AWS.Iot();
        const endpoint = await iot.describeEndpoint(params).promise();
        console.log(endpoint);
        return endpoint.endpointAddress;
    }
```

4. Creating IoT device isn't necessary for pub-sub
5. `a/b/c` and `a/b/c/` aren't the same topic while subscribing or publishing
6. `a/b/#` - `#` is only allowed during subscribing and not with publish, during publishing you have to be specific
7. IoT Rule we used : `SELECT * FROM 'sistech/#' where status = 'false'`

Test

Publish to: sistech/account1/

Publish Format:

```json
{
"topic": "sistech/account1/",
"message": "Hello from AWS Lambda Console",
"status": "false"
}
```

Subscribe to: sistech/userid/account1/#

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