Azure IoT Hub Documentation

Direct Methods

Direct Methods provide a synchronous, bi-directional communication pattern between a cloud solution and an IoT device. They are ideal for commanding a device, retrieving real‑time status, or performing configuration updates.

When to Use Direct Methods

• Triggering immediate actions on a device (e.g., reboot, firmware update)
• Retrieving a one‑time snapshot of device state
• Performing configuration changes that require acknowledgement

How It Works

1. Cloud application calls InvokeMethodAsync on the device identity.
2. The IoT Hub routes the method request to the device client.
3. The device processes the request and returns a response payload and status code.
4. The cloud receives the response synchronously.

Sample Code

using Microsoft.Azure.Devices;
using System;
using System.Text;
using System.Threading.Tasks;

class Program{
    static ServiceClient serviceClient;
    const string connectionString = "";
    const string deviceId = "myDevice";

    static async Task Main(){
        serviceClient = ServiceClient.CreateFromConnectionString(connectionString);
        var method = new CloudToDeviceMethod("reboot")
        {
            ResponseTimeout = TimeSpan.FromSeconds(30)
        };
        var result = await serviceClient.InvokeDeviceMethodAsync(deviceId, method);
        Console.WriteLine($"\nStatus: {result.Status}");
        Console.WriteLine($"Payload: {result.GetPayloadAsJson()}");
    }
}

const { Client } = require('azure-iothub');

const connectionString = '';
const targetDevice = 'myDevice';
const client = Client.fromConnectionString(connectionString);

const methodParams = {
  methodName: 'reboot',
  payload: null,
  timeoutInSeconds: 30
};

client.invokeDeviceMethod(targetDevice, methodParams, (err, result) => {
  if (err) {
    console.error('Failed to invoke method:', err);
  } else {
    console.log('Response status:', result.status);
    console.log('Response payload:', result.payload);
  }
});

Try a Method Request (Demo)