How to use AWS IoT to send/receive messages to/from Web Browser

Question

We are trying to use Amazon Web Services Internet of Things (AWS IoT) to send messages from/to a Web Browser (e.g: . Given that the AWS IoT supports JavaScript we expect that this is possible ...

We have searched at the AWS IoT Documentation but only found server-side examples (which expose AWS secrets/keys...)

Are there any good working examples or tutorials for using AWS IoT to send/receive messages via WebSockets/MQTT in the browser (e.g: authenticating with AWS Cognito)? Thanks!

Answer 1

Here's a sample that uses a cognito identity pool in JS to connect, publish and react to a subscription.

// Configure Cognito identity pool
AWS.config.region = 'us-east-1';
var credentials = new AWS.CognitoIdentityCredentials({
    IdentityPoolId: 'us-east-1:your identity pool guid',
});

// Getting AWS creds from Cognito is async, so we need to drive the rest of the mqtt client initialization in a callback
credentials.get(function(err) {
    if(err) {
        console.log(err);
        return;
    }
    var requestUrl = SigV4Utils.getSignedUrl('wss', 'data.iot.us-east-1.amazonaws.com', '/mqtt',
        'iotdevicegateway', 'us-east-1',
        credentials.accessKeyId, credentials.secretAccessKey, credentials.sessionToken);
    initClient(requestUrl);
});

function init() {
  // do setup stuff
}

// Connect the client, subscribe to the drawing topic, and publish a "hey I connected" message
function initClient(requestUrl) {
    var clientId = String(Math.random()).replace('.', '');
    var client = new Paho.MQTT.Client(requestUrl, clientId);
    var connectOptions = {
        onSuccess: function () {
            console.log('connected');

            // subscribe to the drawing
            client.subscribe("your/mqtt/topic");

            // publish a lifecycle event
            message = new Paho.MQTT.Message('{"id":"' + credentials.identityId + '"}');
            message.destinationName = 'your/mqtt/topic';
            console.log(message);
            client.send(message);
        },
        useSSL: true,
        timeout: 3,
        mqttVersion: 4,
        onFailure: function () {
            console.error('connect failed');
        }
    };
    client.connect(connectOptions);

    client.onMessageArrived = function (message) {

        try {
            console.log("msg arrived: " +  message.payloadString);
        } catch (e) {
            console.log("error! " + e);
        }

    };
}

Documentation for the credentials.get call, here

Remember to authorize your IAM role for subscribing / publishing as well. Here's a sample:

{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Effect": "Allow",
            "Action": [
                "iot:Connect"
            ],
            "Resource": "*"
        },
        {
            "Effect": "Allow",
            "Action": "iot:Receive",
            "Resource": "*"
        },
        {
            "Effect": "Allow",
            "Action": "iot:Subscribe",
            "Resource": [
                "arn:aws:iot:us-east-1::your/mqtt/topic"
            ]
        },
        {
            "Effect": "Allow",
            "Action": "iot:Publish",
            "Resource": [
                "arn:aws:iot:us-east-1::your/mqtt/topic"
            ]
        }
    ]
}