```js // Ensure MQTT.js is installed first // > npm install mqtt import * as mqtt from "mqtt"

// Where 'url' is "mqtts://BROKER.NAMESPACE.cloudflarepubsub.com:8884" function example(url) { let client = mqtt.connect(url, { protocolVersion: 5, reconnectPeriod: 0, username: 'anything', password: jwt, // pass this from a form field in your app clientId: '', })

client.on('connect', function () { client.subscribe(topic, function (err) { if (err) { client.end(); } else { console.log(subscribed to ${topic}) } })

client.on('message', function (topic, message) { let line = (new Date()).toLocaleString('en-US') + ": " + message.toString() + "\n"; console.log(line) }) } ```

Suggested topic structure

What if topic prefixed by device first? is device-1/{cmd|data)?

Useful recipes to design MQTT setups.

Message Queuing Telemetry Transport MQTT protocol -> publish-subscribe network protocol that transports messages between devices, usually through TCP/IP

Protocol defines 2 network entities:

1. message broker -> receives messages from clients and then sends them to any clients subscribed to topic.
2. a number of clients ->

<table style="border: 1px solid black;"> <tr> <th style="border: 1px solid black;"> MQTT un-encrypted port </th> <th style="border: 1px solid black;"> MQTT encrypted port </th> </tr> <tr> <td style="border: 1px solid black;">**1883** </td> <td style="border: 1px solid black;">**8883** </td> </tr> </table>

mqtt cluster