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How to Send telemetry message to Azure IOT Hub using Node Js ?



  • I am able to install node using Opkg Install Node,

    when I create sample program , simple hello world, it is working fine.
    'use strict';
    console.log("Hello world");

    a4ab6fc3-85e9-4a91-b14f-446c65054158-image.png

    however when I run following code in Js,
    // Copyright (c) Microsoft. All rights reserved.
    // Licensed under the MIT license. See LICENSE file in the project root for full license information.

    'use strict';

    // Choose a protocol by uncommenting one of these transports.
    const Protocol = require('azure-iot-device-mqtt').Mqtt;
    // const Protocol = require('azure-iot-device-amqp').Amqp;
    // const Protocol = require('azure-iot-device-http').Http;
    // const Protocol = require('azure-iot-device-mqtt').MqttWs;
    // const Protocol = require('azure-iot-device-amqp').AmqpWs;

    const Client = require('azure-iot-device').Client;
    const Message = require('azure-iot-device').Message;

    // String containing Hostname, Device Id & Device Key in the following formats:
    // "HostName=<iothub_host_name>;DeviceId=<device_id>;SharedAccessKey=<device_key>"
    const deviceConnectionString = process.env.IOTHUB_DEVICE_CONNECTION_STRING;
    let sendInterval;

    function disconnectHandler () {
    clearInterval(sendInterval);
    sendInterval = null;
    client.open().catch((err) => {
    console.error(err.message);
    });
    }

    // The AMQP and HTTP transports have the notion of completing, rejecting or abandoning the message.
    // For example, this is only functional in AMQP and HTTP:
    // client.complete(msg, printResultFor('completed'));
    // If using MQTT calls to complete, reject, or abandon are no-ops.
    // When completing a message, the service that sent the C2D message is notified that the message has been processed.
    // When rejecting a message, the service that sent the C2D message is notified that the message won't be processed by the device. the method to use is client.reject(msg, callback).
    // When abandoning the message, IoT Hub will immediately try to resend it. The method to use is client.abandon(msg, callback).
    // MQTT is simpler: it accepts the message by default, and doesn't support rejecting or abandoning a message.
    function messageHandler (msg) {
    console.log('Id: ' + msg.messageId + ' Body: ' + msg.data);
    client.complete(msg, printResultFor('completed'));
    }

    function generateMessage () {
    const windSpeed = 10 + (Math.random() * 4); // range: [10, 14]
    const temperature = 20 + (Math.random() * 10); // range: [20, 30]
    const humidity = 60 + (Math.random() * 20); // range: [60, 80]
    const data = JSON.stringify({ deviceId: 'myFirstDevice', windSpeed: windSpeed, temperature: temperature, humidity: humidity });
    const message = new Message(data);
    message.properties.add('temperatureAlert', (temperature > 28) ? 'true' : 'false');
    return message;
    }

    function errorHandler (err) {
    console.error(err.message);
    }

    function connectHandler () {
    console.log('Client connected');
    // Create a message and send it to the IoT Hub every two seconds
    if (!sendInterval) {
    sendInterval = setInterval(() => {
    const message = generateMessage();
    console.log('Sending message: ' + message.getData());
    client.sendEvent(message, printResultFor('send'));
    }, 2000);
    }
    }

    // fromConnectionString must specify a transport constructor, coming from any transport package.
    let client = Client.fromConnectionString(deviceConnectionString, Protocol);

    client.on('connect', connectHandler);
    client.on('error', errorHandler);
    client.on('disconnect', disconnectHandler);
    client.on('message', messageHandler);

    client.open()
    .catch(err => {
    console.error('Could not connect: ' + err.message);
    });

    // Helper function to print results in the console
    function printResultFor(op) {
    return function printResult(err, res) {
    if (err) console.log(op + ' error: ' + err.toString());
    if (res) console.log(op + ' status: ' + res.constructor.name);
    };
    }
    I am getting following error, can some one help here to resolve this issue ?
    6a0f1254-0e9a-4dd4-96d2-10c61c4f41bd-image.png



  • @somnathavhad move your file Device.js to the root directory, then from the root directory execute the command node ./Device.js

    You will receive an error but please post the error message.



  • @crispyoz I tried to run it from root folder, please go through below error.
    79b944e1-0643-4642-a39d-bc9ad6cfe9b4-image.png

    then I try to run npm install, it has created Package.jason in root folder. I tried to run Device.js had same issues
    f820ce63-ea36-410c-879c-e3ac84529db0-image.png



  • @somnathavhad if you re-run:

    node --max_old_space_size=512 $(which npm) install azure-iot-device-mqtt

    What is the output?



  • @crispyoz : I get following error. I

    7fe2f974-78c0-49a8-91e8-0bae0985fba0-image.png



  • @crispyoz I shared results. Still not able to proceed. It seems I need to upgrade node js version. ?



  • @somnathavhad I was able to duplicate your issue, it appears there is a mismatch with node and npm. I took a new Omega2Pro out of the box. Run oupgrade so to be on the latest stable firmware. Next follow the document link I sent.

    Now if you run the command "npm i" to get the npm information, this will tell you that you should upgrade npm to a new version. If I do upgrade npm then your error will occur, if I do not upgrade npm then npm has no error and can install the azure-iot-device-mqtt

    From this I conclude you have installed an incompatible npm. I don't think you can upgrade node because Onion Team produced a custom version of node so it could work on Omega2.



  • @crispyoz Thank you for your support and help very much appreciated . I see some thing wrong with my installation , I tried on brand new omega 2S and I am able to run the Node JS code and send data from Omega to Azure cloud. I am good now.



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