var DeviceClient = require('azure-iot-device').Client
var DeviceProtocol = require('azure-iot-device-amqp').AmqpWs

[...]

var connectionString = "HostName=.....";

[...]

var client = DeviceClient.fromConnectionString(connectionString, DeviceProtocol);

[...]

client.on('message', onMessage);

function onMessage(msg) {
  console.log('Id: ' + msg.messageId + ' Body: ' + msg.data);
  messageController.exec(JSON.parse(msg.data.toString()));
  client.complete(msg, printResultFor('completed'));
}