IoT Edge Identity Translation Module Sample

app.js

'use strict';

const Transport = require('azure-iot-device-mqtt').Mqtt;
const ModuleClient = require('azure-iot-device').ModuleClient;
const Message = require('azure-iot-device').Message;
const DeviceClient = require('azure-iot-device').Client;

let simulatedTemperatureClient;

ModuleClient.fromEnvironment(Transport, function (err, moduleClient) {
  if (err) {
    throw err;
  } else {
    moduleClient.on('error', function (err) {
      throw err;
    });

    // connect to the Edge instance
    moduleClient.open(function (err) {
      if (err) {
        throw err;
      } else {
        console.log('IoT Hub module client initialized');

        const simulatedTemperatureClientConnectionString = process.env.simulatedTemperatureClientConnectionString;
        if (simulatedTemperatureClientConnectionString) {
          console.log("Device Connection string", simulatedTemperatureClientConnectionString);
          simulatedTemperatureClient = DeviceClient.fromConnectionString(simulatedTemperatureClientConnectionString, Transport);
        }
        else {
          console.log("Please configure the device connection string in environment variables");
        }


        // Act on input messages to the module.
        moduleClient.on('inputMessage', function (inputName, msg) {
          console.log("new message received", msg);
          if (simulatedTemperatureClient) {
            // Identity Translation configured, wrap message fro IoT device
            const message = msg.getBytes().toString('utf8');
            const sensorMsg = new Message(message);
            simulatedTemperatureClient.sendEvent(sensorMsg);
          } else {
            // No Identity Translation configured, send message through module
            pipeMessage(moduleClient, inputName, msg);
          }
        });
      }
    });
  }
});


// This function just pipes the messages without any change.
function pipeMessage(client, inputName, msg) {
  client.complete(msg, printResultFor('Receiving message'));

  if (inputName === 'input1') {
    var message = msg.getBytes().toString('utf8');
    if (message) {
      var outputMsg = new Message(message);
      client.sendOutputEvent('output1', outputMsg, printResultFor('Sending received 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);
    }
  };
}