Azure IoT Hub has capabilities that can be used by a developer to build robust device management. There could be different use cases or scenarios across multiple industries, but these device management capabilities, their patterns, and the SDK code remains the same, saving significant time in developing and managing, along with maintaining millions of devices.

Device management will be the central part of any IoT solution. The IoT solution helps users to manage devices remotely, take actions from cloud-based applications such as disable, update data, run any command, and firmware updates.

In this chapter, we are going to perform all these tasks for device management, and we will start with creating the device.

This sample application is focused on device registry operations and how they work. We will create a console application as our first IoT solution and look at the various device management techniques.

Let's create a console application to start with IoT:

1. Create a new project in Visual Studio:

2. Add the IoT Hub connectivity extension in Visual Studio:

3. Now, right-click on the Solution in Visual Studio, navigate to Add, and select Connected Services.
4. Select Azure IoT Hub and click on Add.
5. Now, select the Azure subscription from the dropdown, followed by which you will get a list of the IoT Hub service parts...

Firstly, we need to understand what a device twin is. We will be following some steps to use a device twin to understand their purpose and where we can use the device twin in any IoT solution. The device twin is a JSON formatted document that describes the metadata, properties of any device created within IoT Hub. It describes the individual device specific information.

The device twin is made up of: tags, desired properties, and reported properties. The operations that can be done on an IoT device is to update the data or query for any IoT device. this feature can be built into the IoT Solution from where a Administrator user can initiate these.

Tags hold the device metadata that can be accessed from an IoT solution only. The desired properties are set from the IoT solution and can be accessed on the device. Whereas the reported properties are set on the device and...

Azure IoT Hub provides fully managed bidirectional communication between the IoT solution on the backend and the IoT devices in the fields. We will be considering detailed message communication in Chapter 3, IoT Hub Messaging and Commands.

When there is a need for an immediate communication result, a direct method best suits these scenarios. Let's take an example of a home automation system. One needs to control the AC temperature or turn the faucet showers on/off. It uses the HTTP protocol for method invocation.

The following steps will be taken to perform a direct method with an IoT device connected with IoT Hub:

1. Invoke this method from the application:

public async Task<CloudToDeviceMethodResult...

In a typical scenario, the device administrator or operators are required to manage devices in bulk. In the earlier sections, we looked at the device twin, which maintains properties and tags. Conceptually, the job is nothing but a wrapper on the possible actions, which can be done in bulk.

Suppose we have a scenario in which we need to update the properties for multiple devices; in such a case, one can schedule the job and track the progress of the job. I would like to set the frequency to send the data every 1 hour instead of every 30 minutes for 1000 IoT devices. Another example could be to reboot multiple devices at the same time.

IoT Hub supports a SQL-like language to retrieve information regarding device twins, jobs, and message routing. Basically, you can write a basic SQL command and that will be executed against the device registry.

Each query follows the syntax like SQL; it has the standard SELECT, FROM, and WHERE keywords used to retrieve the result set in the result window.

In this section, we will follow the steps to use the query explorer and retrieve the device information in the results window:

1. we will select the IoT Hub IoTHubCookBook service from the Azure portal.
2. Select Query Explorer:

3. Using the execution windows, type the query you want to execute:

4. The output will be shown in the result...