Schedule and broadcast jobs (Azure CLI)

Artikkeli
03/15/2023

Use Azure IoT Hub to schedule and track jobs that update millions of devices. Use jobs to:

Update desired properties
Update tags
Invoke direct methods

Conceptually, a job wraps one of these actions and tracks the progress of execution against a set of devices. The set of devices with which a job interacts is defined by a device twin query. For example, a back-end app can use a job to invoke a reboot method on 10,000 devices, specified by a device twin query and scheduled at a future time. That application can then track progress as each of those devices receives and executes the reboot method.

Learn more about each of these capabilities in these articles:

Device twin and properties: Get started with device twins and Understand and use device twins in IoT Hub
Direct methods: IoT Hub developer guide - direct methods

Note

The features described in this article are available only in the standard tier of IoT Hub. For more information about the basic and standard/free IoT Hub tiers, see Choose the right IoT Hub tier for your solution.

This article shows you how to create two Azure CLI sessions:

A session that creates a simulated device. The simulated device is configured to return a status code and JSON payload when any direct method is invoked.
A session that creates two scheduled jobs. The first job invokes a direct method and the second job updates a desired device twin property on the simulated device created in the other session.

Prerequisites

Azure CLI. You can also run the commands in this article using the Azure Cloud Shell, an interactive CLI shell that runs in your browser or in an app such as Windows Terminal. If you use the Cloud Shell, you don't need to install anything. If you prefer to use the CLI locally, this article requires Azure CLI version 2.36 or later. Run az --version to find the version. To locally install or upgrade Azure CLI, see Install Azure CLI.
An IoT hub in your Azure subscription. If you don't have a hub yet, you can follow the steps in Create an IoT hub.
Make sure that port 8883 is open in your firewall. The device sample in this article uses MQTT protocol, which communicates over port 8883. This port may be blocked in some corporate and educational network environments. For more information and ways to work around this issue, see Connecting to IoT Hub (MQTT).

Prepare the Cloud Shell

If you want to use the Azure Cloud Shell, you must first launch and configure it. If you use the CLI locally, skip to the Prepare two CLI sessions section.

Select the Cloud Shell icon from the page header in the Azure portal.

Note

If this is the first time you've used the Cloud Shell, it prompts you to create storage, which is required to use the Cloud Shell. Select a subscription to create a storage account and Microsoft Azure Files share.
Use the environment selector in the Cloud Shell toolbar to select your preferred CLI environment. This article uses the Bash environment. You can also use the PowerShell environment.

Note

Some commands require different syntax or formatting in the Bash and PowerShell environments. For more information, see Tips for using the Azure CLI successfully.

Prepare two CLI sessions

Next, you must prepare two Azure CLI sessions. If you're using the Cloud Shell, you run these sessions in separate Cloud Shell tabs. If using a local CLI client, you run separate CLI instances. Use the separate CLI sessions for the following tasks:

The first session simulates an IoT device that communicates with your IoT hub.
The second session schedules jobs for your simulated device with your IoT hub.

Note

Azure CLI requires you to be logged into your Azure account. If you're using the Cloud Shell, you're automatically logged into your Azure account. If you're using a local CLI client, you must log into each CLI session. All communication between your Azure CLI shell session and your IoT hub is authenticated and encrypted. As a result, this article doesn't need extra authentication that you'd use with a real device, such as a connection string. For more information about logging in with Azure CLI, see Sign in with Azure CLI.

In the first CLI session, run the az extension add command. The command adds the Microsoft Azure IoT Extension for Azure CLI to your CLI shell. The extension adds IoT Hub, IoT Edge, and IoT Device Provisioning Service (DPS) specific commands to Azure CLI. After you install the extension, you don't need to install it again in any Cloud Shell session.
```
az extension add --name azure-iot
```
Note

This article uses the newest version of the Azure IoT extension, called azure-iot. The legacy version is called azure-cli-iot-ext.You should only have one version installed at a time. You can use the command az extension list to validate the currently installed extensions.

Use az extension remove --name azure-cli-iot-ext to remove the legacy version of the extension.

Use az extension add --name azure-iot to add the new version of the extension.

To see what extensions you have installed, use az extension list.
Open the second CLI session. If you're using the Cloud Shell in a browser, select the Open new session icon on the toolbar of your first CLI session. If using the CLI locally, open a second CLI instance.

Create and simulate a device

In this section, you create a device identity for your IoT hub in the first CLI session, and then simulate a device using that device identity. The simulated device responds to the jobs that you schedule in the second CLI session.

To create and start a simulated device:

In the first CLI session, run the az iot hub device-identity create command, replacing the following placeholders with their corresponding values. This command creates the device identity for your simulated device.

{DeviceName}. The name of your simulated device.

{HubName}. The name of your IoT hub.
```
az iot hub device-identity create --device-id {DeviceName} --hub-name {HubName} 
```
In the first CLI session, run the az iot device simulate command, replacing the following placeholders with their corresponding values. This command simulates the device you created in the previous step. The simulated device is configured to return a status code and payload whenever a direct method is invoked.

{DeviceName}. The name of your simulated device.

{HubName}. The name of your IoT hub.
```
az iot device simulate --device-id {DeviceName} --hub-name {HubName} \
                       --method-response-code 201 \
                       --method-response-payload '{"result":"Direct method successful"}'
```
Tip

By default, the az iot device simulate command sends 100 device-to-cloud messages with an interval of 3 seconds between messages. The simulation ends after all messages have been sent. If you want the simulation to run longer, you can use the --msg-count parameter to specify more messages or the --msg-interval parameter to specify a longer interval between messages. You can also run the command again to restart the simulated device.

Schedule a job to invoke a direct method

In this section, you schedule a job in the second CLI session to invoke a direct method on the simulated device running in the first CLI session.

Confirm that the simulated device in the first CLI session is running. If not, restart it by running the az iot device simulate command again from Create and simulate a device.
In the second CLI session, run the az iot hub job create command, replacing the following placeholders with their corresponding values. In this example, there's no pre-existing method for the device. The command schedules a job that calls an example method name on the simulated device, providing a null value for the method's payload. The method provides a status code and payload in its response.

{HubName}. The name of your IoT hub.

{JobName}. The name of your scheduled job. Job names are unique, so choose a different job name each time you run this command.

{MethodName}. The name of your direct method. The simulated device doesn't have a pre-existing method, so you can choose any name you want for this command.

{DeviceName}. The name of your simulated device.
```
az iot hub job create --hub-name {HubName} --job-id {JobName} \
                      --job-type scheduleDeviceMethod \
                      --method-name {MethodName} --method-payload 'null' \
                      --query-condition "deviceId = '{DeviceName}'"
```
Tip

When scheduling a job az iot hub job create command that invokes a direct method, you must specify values for both the --method-name and --method-payload optional parameters. For direct methods that don't accept a payload, specify null for the --method-payload parameter.
In the first CLI session, confirm that the output shows the method invocation. In the following screenshot, we used SampleDevice andSampleMethod for the {DeviceName} and {MethodName} placeholders, respectively, in the az iot hub job create CLI command from the previous step.

Schedule a job to update a device twin's properties

In this section, you schedule a job in the second CLI session to update a desired device twin property on the simulated device running in the first CLI session.

Confirm that the simulated device in the first CLI session is running. If not, restart it by running the az iot device simulate command again from Create and simulate a device.
In the second CLI session, run the az iot hub job create command, replacing the following placeholders with their corresponding values. In this example, we're scheduling a job to set the value of the desired twin property BuildingNo to 45 for our simulated device.

{HubName}. The name of your IoT hub.

{JobName}. The name of your scheduled job. Job names are unique, so choose a different job name each time you run this command.

{DeviceName}. The name of your simulated device.
```
az iot hub job create --hub-name {HubName} --job-id {JobName} \
                      --job-type scheduleUpdateTwin \
                      --twin-patch '{"properties":{"desired": {"BuildingNo": 45}}}' \
                      --query-condition "deviceId = '{DeviceName}'"
```
In the first CLI session, confirm the output shows the successful update for the reported device twin property, indicating that the desired device twin property was also updated.

Next steps

In this article, you used Azure CLI to simulate a device and schedule jobs to run a direct method and update the device twin's properties for that simulated device.

To continue exploring IoT hub and device management patterns, update an image in Device Update for Azure IoT Hub tutorial using the Raspberry Pi 3 B+ Reference Image.

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