Cross Platform IoT: Devices operations using IoT Hub Explorer

Cross Platform IoT: Devices operations using IoT Hub Explorer

This post is part of a Cross-Platform IoT series, to see other posts in the series refer here.

IoT Hub Explorer is a node.js based cross platform tool that allows management of device for an existing IoT Hub.

This is one of my favorite tools for Azure IoT Hub development and troubleshooting. It is a command line tool that can run on Windows, Mac or Linux and provides an easy way to execute operations on Azure IoT Hub such as device creation, send a message to an existing device, etc. It comes in handy when you are doing Dev. Testing or even demonstrating the capabilities of the Azure IoT service. You can theoretically use this for troubleshooting a production environment as well, but I would recommend having appropriate telemetry and an operational management pipeline for those scenarios. One of the very useful features I like about this tool is the ability to monitor messages on devices for the IoT Hub, basically getting event data and operational statistics about devices in the hub. We will use this tool to create a device and then watch IoT Hub for messages. IoT Hub Explorer is available on GitHub here.

Note that the Azure IoT CLI (covered in the last post) also has support for managing devices and may soon overlap with functionalities of IoT Hub Explorer. When that happens, Azure CLI should become the preferred tool for all IoT Hub operations.

Let’s use IoT Hub Explorer to create and monitor a device. Before we do that, we need to install it. Being a node package, you can install it through npm.

npm install -g iothub-explorer

Since IoT Hub Explorer is a separate utility, we will need to first login using our IoT Hub connection string. Open a bash terminal and enter the following:

iothub-explorer login ";SharedAccessKeyName=iothubowner;SharedAccessKey=yourkey"

If you do not have the connection string handy, you can use the az iot hub show-connection-string -g youresourcegroup command described in the previous section to fetch your IoT Hub connection string. The login command should open a temporary session with the IoT Hub token policy provided. The default TTL for this session is 1 hour.

Session started, expires on Wed Mar 15 2017 19:59:05 GMT-0500 (CDT)
Session file: /Users/niksac/Library/Application Support/iothub-explorer/config

Note that the above command uses the connection string for iothubowner policy which gives complete control over your IoT Hub.

Creating a new device

To create a new device using IoT Hub explorer, type the following command:

iothub-explorer create -a

The -a flag is used to auto-generate a Device Id and credentials when creating the device. You can also specify a custom Device Id or a Device JSON file to customize the device creation. There are other options to specify credentials such as the symmetric key and X.509 certificates. We will cover those in a separate IoT Hub Security post, for now, we use the default credentials generated by IoT Hub.

If all goes well, you should see an output similar to below:

deviceId:                   youdeviceId
generationId:               63624558311459675
connectionState:            Disconnected
status:                     enabled
statusReason:               null
connectionStateUpdatedTime: 0001-01-01T00:00:00
statusUpdatedTime:          0001-01-01T00:00:00
lastActivityTime:           0001-01-01T00:00:00
cloudToDeviceMessageCount:  0
    primaryKey:   symmetrickey1=
    secondaryKey: symmetrickey2=
    primaryThumbprint:   null
    secondaryThumbprint: null
connectionString: ;DeviceId=youdeviceId;SharedAccessKey=symmetrickey=

Few important things, the obvious one here is the connectionString. It provides a unique Device Connection string to talk to the device. The privileges for the device connection string are based on the device policy defined in IoT Hub and gives them DeviceConnect permissions only. The policy-based control allows our endpoints to be secure and limited to use with only the specific device. You can learn more about IoT Hub device security here. Also, notice that the device is enabled but the status is disconnected. What this means is that the device has been successfully registered in IoT Hub. However, there are no active connections to it.

Sending and Receiving messages

Lets initiate a connection by sending a device ingestion request. There are multiple ways in IoT Hub Explorer to send and receive messages. One of the options that are useful is a simulate-device command. The simulate-device command allows the tool to behave like a device ingestion and command simulator. It can be used to send Telemetry custom messages and Commands on behalf of the device. The functionality comes handy when you want to perform some Dev. Integration tests on your device, and you don’t want to write too much code. You can create messages and view the send and receive flow simultaneously. The command also exposes properties such as send-interval and send-count and receive-countwhich allows for configuring the simulation. Note that this is not a penetration or load testing tool, it is enabling a feature for you to perform some initial tests before performing more involved test cases. Let send a series of messages on our created device (from Part 1) and then receive a Command message.

Send a message

The following command sends 5 messages every 2 seconds to a specified Device Id.

niksac$ iothub-explorer simulate-device --send "Hello from IoT Hub Explorer" --device-connection-string ";DeviceId=D1234;SharedAccessKey==" --send-count 5 --send-interval 2000  

The output for the messages will look like this:

Message #0 sent successfully
Message #1 sent successfully
Message #2 sent successfully
Message #3 sent successfully
Message #4 sent successfully
Device simulation finished.

Monitoring Messages

Another useful feature in IoT Hub Explorer is that it allows you to monitor the event of your device or IoT Hub as a whole. This comes in very handy when you want to troubleshoot your IoT Hub instance. For example, you want to check if messages are flowing correctly in IoT Hub. You can use the monitor-events command to log all events for the device of Hub to the terminal; you can also use the monitor-ops command to monitor the operation endpoint for IoT Hub.

To monitor events, enter the following:

iothub-explorer monitor-events --login ";SharedAccessKeyName=iothubowner;SharedAccessKey=="

The above created a listener which is now looking for any activating happing on the entire IoT Hub. As mentioned earlier, you can specify a Device connection string to monitor for a specific device.

Now, when you send a message or command to any device in your IoT Hub, you should start seeing the output in the terminal. For example, if you open a monitor-event listener in a terminal window and then execute the simulate-device --send command again, you should see following output in the terminal:

Monitoring events from all devices...
==== From: D1234 ====
Hello from IoT Hub Explorer
==== From: D1234 ====
Hello from IoT Hub Explorer
==== From: D1234 ====
Hello from IoT Hub Explorer
==== From: D1234 ====
Hello from IoT Hub Explorer
==== From: D1234 ====
Hello from IoT Hub Explorer

There are multiple other useful commands in IoT Hub Explorer such as Import, Export devices, regenerate SAS tokens, device management commands. You should play around with the IoT Hub Explorer commands and options; it can save you from writing some piece of code for common operations.

In the next post, we talk about another useful utility for troubleshooting and diagnostics.

This post is part of a Cross-Platform IoT series, to see other posts in the series refer here.

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