state-subscription-example

gistfile1.js

process.env.GOOGLE_APPLICATION_CREDENTIALS = 'gCloudAuth.json';

const fs = require('fs');
const path = require('path');
const jwt = require('jsonwebtoken');
const mqtt = require('mqtt');
const { PubSub } = require('@google-cloud/pubsub');

const pubSubClient = new PubSub();

const createJwt = (projectId, privateKeyFile) => {
  const token = {
    iat: parseInt(Date.now() / 1000),
    exp: parseInt(Date.now() / 1000) + 20 * 60,
    aud: projectId,
  };
  const privateKey = fs.readFileSync(privateKeyFile);
  return jwt.sign(token, privateKey, { algorithm: 'RS256' });
};

const projectId = 'portal-dev-340714';
const region = 'europe-west1';
const registryId = 'tests';
const deviceId = 'test1';
const rootsCertsFile = path.join(__dirname, 'resources', 'roots.pem');
const privateKeyFile = path.join(__dirname, 'resources', 'private.pem');

const mqttClientId = `projects/${projectId}/locations/${region}/registries/${registryId}/devices/${deviceId}`;

function listenForMessages() {
  const subscription = pubSubClient.subscription('tests-state');

  const messageHandler = (message) => {
    const payload = JSON.parse(message.data.toString());
    console.log(message.attributes);
    console.log(payload);
    message.ack();
  };

  subscription.on('message', messageHandler);
}

const connectDevice = () => {
  const connectionArgs = {
    host: 'mqtt.googleapis.com',
    port: '8883',
    clientId: mqttClientId,
    username: 'unused',
    password: createJwt(projectId, privateKeyFile),
    protocol: 'mqtts',
    secureProtocol: 'TLSv1_2_method',
    ca: [fs.readFileSync(rootsCertsFile)],
  };

  const client = mqtt.connect(connectionArgs);
  return client;
};

listenForMessages();
const iotClient = connectDevice();

iotClient.on('connect', (success) => {
  console.log('connect');
  if (!success) {
    console.log('Client not connected...');
  } else {
    console.log('connected');
    iotClient.publish('/devices/test1/state', JSON.stringify({ a: 1 }), (err) =>
      console.log(err),
    );
  }
});