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Send telemetry to Azure IoT Hub quickstart (Node.js) | Microsoft Docs
In this quickstart, you run two sample Node.js applications to send simulated telemetry to an IoT hub and to read telemetry from the IoT hub for processing in the cloud.
dominicbetts
timlt
iot-hub
iot-hub
node
quickstart
mvc
06/19/2018
dobett

Quickstart: Send telemetry from a device to an IoT hub and read the telemetry from the hub with a back-end application (Node.js)

[!INCLUDE iot-hub-quickstarts-1-selector]

IoT Hub is an Azure service that enables you to ingest high volumes of telemetry from your IoT devices into the cloud for storage or processing. In this quickstart, you send telemetry from a simulated device application, through IoT Hub, to a back-end application for processing.

The quickstart uses two pre-written Node.js applications, one to send the telemetry and one to read the telemetry from the hub. Before you run these two applications, you create an IoT hub and register a device with the hub.

[!INCLUDE cloud-shell-try-it.md]

If you don’t have an Azure subscription, create a free account before you begin.

Prerequisites

The two sample applications you run in this quickstart are written using Node.js. You need Node.js v4.x.x or later on your development machine.

You can download Node.js for multiple platforms from nodejs.org.

You can verify the current version of Node.js on your development machine using the following command:

node --version

Download the sample Node.js project from https://github.com/Azure-Samples/azure-iot-samples-node/archive/master.zip and extract the ZIP archive.

Create an IoT hub

[!INCLUDE iot-hub-include-create-hub]

Register a device

A device must be registered with your IoT hub before it can connect. In this quickstart, you use the Azure Cloud Shell to register a simulated device.

  1. Run the following commands in Azure Cloud Shell to add the IoT Hub CLI extension and to create the device identity.

    YourIoTHubName : Replace this placeholder below with the name you choose for your IoT hub.

    MyNodeDevice : This is the name given for the registered device. Use MyNodeDevice as shown. If you choose a different name for your device, you will also need to use that name throughout this article, and update the device name in the sample applications before you run them.

    az extension add --name azure-cli-iot-ext
az iot hub device-identity create --hub-name YourIoTHubName --device-id MyNodeDevice

  2. Run the following commands in Azure Cloud Shell to get the device connection string for the device you just registered:

    YourIoTHubName : Replace this placeholder below with the name you choose for your IoT hub.

    az iot hub device-identity show-connection-string --hub-name YourIoTHubName --device-id MyNodeDevice --output table

    Make a note of the device connection string, which looks like:

    HostName={YourIoTHubName}.azure-devices.net;DeviceId=MyNodeDevice;SharedAccessKey={YourSharedAccessKey}

    You use this value later in the quickstart.

  3. You also need a service connection string to enable the back-end application to connect to your IoT hub in order to retrieve the messages. The following command retrieves the service connection string for your IoT hub:

    YourIoTHubName : Replace this placeholder below with the name you choose for your IoT hub.

    az iot hub show-connection-string --hub-name YourIoTHubName --output table

    Make a note of the service connection string, which looks like:

    HostName={YourIoTHubName}.azure-devices.net;SharedAccessKeyName=iothubowner;SharedAccessKey={YourSharedAccessKey}

    You use this value later in the quickstart. The service connection string is different from the device connection string.

Send simulated telemetry

The simulated device application connects to a device-specific endpoint on your IoT hub and sends simulated temperature and humidity telemetry.

  1. Open your local terminal window, navigate to the root folder of the sample Node.js project. Then navigate to the iot-hub\Quickstarts\simulated-device folder.

  2. Open the SimulatedDevice.js file in a text editor of your choice.

    Replace the value of the connectionString variable with the device connection string you made a note of previously. Then save your changes to SimulatedDevice.js file.

  3. In the local terminal window, run the following commands to install the required libraries and run the simulated device application:

    npm install
node SimulatedDevice.js

    The following screenshot shows the output as the simulated device application sends telemetry to your IoT hub:

    Run the simulated device

Read the telemetry from your hub

The back-end application connects to the service-side Events endpoint on your IoT Hub. The application receives the device-to-cloud messages sent from your simulated device. An IoT Hub back-end application typically runs in the cloud to receive and process device-to-cloud messages.

  1. Open another local terminal window, navigate to the root folder of the sample Node.js project. Then navigate to the iot-hub\Quickstarts\read-d2c-messages folder.

  2. Open the ReadDeviceToCloudMessages.js file in a text editor of your choice.

    Replace the value of the connectionString variable with the service connection string you made a note of previously. Then save your changes to the ReadDeviceToCloudMessages.js file.

  3. In the local terminal window, run the following commands to install the required libraries and run the back-end application:

    npm install
node ReadDeviceToCloudMessages.js

    The following screenshot shows the output as the back-end application receives telemetry sent by the simulated device to the hub:

    Run the back-end application

Clean up resources

[!INCLUDE iot-hub-quickstarts-clean-up-resources]

Next steps

In this quickstart, you've setup an IoT hub, registered a device, sent simulated telemetry to the hub using a Node.js application, and read the telemetry from the hub using a simple back-end application.

To learn how to control your simulated device from a back-end application, continue to the next quickstart.

[!div class="nextstepaction"] Quickstart: Control a device connected to an IoT hub