Creating Azure IoT Hub

To create Azure IoT Hub, you should have an active Azure account. You can log on to https://portal.azure.com/ with your account. On the left-hand menu on the Azure dashboard, click “IoT Hub” so you see the Azure IoT Hub dashboard, as shown in Figure 8-4.

Fill in all required fields to create a new IoT Hub, which is included in your Azure subscription scheme. For instance, I created an Azure IoT Hub, called contiki-ng. After creating an Azure IoT Hub, you should see it on the Azure IoT Hub dashboard, which is shown in Figure 8-5.

The next step is to register a new IoT device in order for it to access Azure IoT Hub. We will perform this task in the next section.

Registering a New IoT Device

Each IoT device that will access Azure IoT Hub should be registered in order to get an access key. Open your Azure IoT Hub and then click the “IoT Devices” menu so you see a list of IoT devices.

You can register a new IoT device by clicking the “+ Add” icon. You should get a registration form, shown in Figure 8-6.

Fill in your IoT device name. Select “Symmetric Key” for authentication type. You can check the box for “Auto Generate Keys” to generate keys automatically. Please select “Enable” for activating your IoT device. Click the Save button if you are done to add the IoT device.

Copying Device Keys

After you have registered all IoT devices that will access Azure IoT Hub, you need to copy all IoT device keys. To obtain these keys, you can click your IoT devices on the Azure IoT Hub to get detailed information from the device.

You should see the IoT device key in the “Primary key” and “Connection string” fields. You can see it in Figure 8-7. You can copy the text that is indicated by an arrow. We will use these keys in our program.

Next, we will develop programs for Contiki-NG and a middleware application to communicate with the Azure IoT Hub. We will perform this task in the next section.

Developing Programs for Contiki-NG

On the Contiki-NG side, we develop two programs for Contiki-NG, starting with the rpl-border-router and sensor program. You can find the rpl-border-router in the Contiki-NG program samples. You should compile and upload rpl-border-router to one of the Contiki-NG motes. You can read how to implement rpl-border-router in Chapter 6.

A sensor program is a web server that serves requests for sensor data. We use the websense program from Chapter 6. We set our project name as websense-Cloud. We rename websense.c as websense-Cloud.c. You can see the project structure of websense-Cloud in Figure 8-8.

In the Makefile file, you can configure the demo project to include http-simple.c and the Contiki-NG project. You can write these scripts:

We also modify the websense-Cloud.c file that is copied from the websense.c file (Chapter 6). In the generate_routes() method, we modify code in order to serve requests for sensor data. You can write this code:

Save all changes. Compile the rpl-border-router and websense-Cloud programs. Then, upload those to your Contiki-NG motes.

Next, we will develop the middleware application using Node.js.

Building Azure Middleware Application

We will develop an Azure middleware application to request sensor data from Contiki-NG and push sensor data to Azure IoT Hub. For implementation, we use Node.js.

First, create a folder for your project. Open Terminal and navigate to your project folder. Then, initialize your project, including required libraries. Type these commands:

Now, we will start to write a middleware application for Azure. Create a file, called middleware-azure.js. Initialize all required libraries and run the web server on port 3000. You also need information such as hostname, device ID, and shared access key. Write this code:

Next, we declare two functions. One of these functions, printResultFor() , is used to print all messages to Terminal. The other is the callback function, connectCallback, which requests sensor data from Contiki-NG motes:

You should replace the value [fd00::212:4b00:797:6083] with the IPv6 address from the Contiki-NG mote that runs the websense-Cloud application.

Finally, we call our callback function from the Azure object:

Save all these codes.

Developing Sensor Consumer Program

The last step is to develop a sensor consumer program to subscribe to Azure IoT Hub in order to retrieve sensor data.

We use the same project from the previous section. We need the azure-vent-hubs library to create the subscription. Type this command:

Then, we create a file, called azure-sensor-subscriber.js. We initialize a required library and configure a connection string for the Azure IoT Hub. Write this code:

Change connectionString to the previous value.

Now, we subscribe and listen to incoming messages from Azure IoT Hub. Write this code:

Save all files.

We have written all programs for this demo. Next, we will test our project.

Creating a New IoT Thing

Each IoT device that wants to access AWS IoT should be registered so as to obtain the access keys included with the security certificate.

First, open a browser and navigate to https://aws.amazon.com/iot/ , so you should see the AWS IoT dashboard shown in Figure 8-12.

On the left-hand menu, click “Manage Things.” If you don’t create things yet, you can click “Register a thing” to register a new IoT device.

After clicking, you should get a form like that shown in Figure 8-13. To simply begin a registration process, click “Create a single thing.”

You should fill in the IoT device information. A thing name is required. For instance, I called my thing contiki-ng-middleware. You can see it in Figure 8-14.

If you have finished creating a thing, you should get the form that is shown in Figure 8-15. To access AWS IoT, we need a certificate. In this demo, we create a new certificate. You can use your own certificate. Click “Create certification.”

After clicking that button, you should see the form that is shown in Figure 8-16. To activate your certificate, click the “Activate” button.

Download all files for the certificate and public/private keys. You also need to download a root CA (Certificate Authority) for AWS IoT from the link shown in Figure 8-16. Put them in a folder; for instance, certs. You can see my certificate and key files in Figure 8-17.

Now, you should see the created thing in the Manage Things dashboard, shown in Figure 8-18. You can create more than two things for AWS IoT.

Next, we will create a policy to enable our thing to access the AWS IoT Hub.

Creating a Policy for AWS IoT

In this section, we will create a policy for AWS IoT. We need this policy to manage all device access. You can find a policy dashboard by clicking “Secure,” then “Policies.” You can see it in Figure 8-19.

Click “Create a policy.” Then, you should see the form shown in Figure 8-20. Fill in the policy name. Next, you should add statements to work with AWS IoT. You should add resource, action, and effect for four items, as follows:

{

  "Version": "2012-10-17",

  "Statement": [

    {

      "Effect": "Allow",

      "Action": "iot:Connect",

      "Resource": "*"

    },

    {

      "Effect": "Allow",

      "Action": "iot:Publish",

      "Resource": "*"

    },

    {

      "Effect": "Allow",

      "Action": "iot:Subscribe",

      "Resource": "*"

    },

    {

      "Effect": "Allow",

      "Action": "iot:Receive",

      "Resource": "*"

    }

  ]

}

After creating a policy, you can verify your policy in Secure ➤ Policies from the AWS IoT dashboard. You can see it in Figure 8-21.

Next, we map a policy and a thing to a certificate. We will perform this in the next section.

Attaching a Policy and a Thing to a Certificate

Your policy and thing should be mapped to a certificate that is already activated in AWS IoT. To perform this task, you can visit Secure ➤ Certificates. You should see your certificate. Click the ... icon so you see the context menu shown in Figure 8-22.

Click menu Attach policy so you see the form dialog that is shown in Figure 8-23. Select your policy that has already been created. If done, click the Attach button.

Next, we should attach the thing to a certificate. From Figure 8-22, select menu “Attach thing” so you get the form dialog shown in Figure 8-24.

Select your thing that was already created.

Finally, you have to set up AWS IoT. Next, we will develop programs for Contiki-NG and the middleware application.

Developing Programs for Contiki-NG

Since our demo scenario is similar to the previous demo, we use the same configuration. You need one Contiki-NG mote as the 6LoWPAN router. Other Contiki-NG motes run the sensor application.

Please read the first demo to build programs for Contiki-NG.

Building Middleware Application for AWS IoT

We build an AWS middleware application to request sensor data from Contiki-NG and push sensor data to AWS IoT. For implementation, we use Node.js.

To create a project, you can create a folder. Then, open Terminal and navigate to your project folder. Then, initialize your project, including the required libraries. Type these commands:

Now, we start to write a middleware application for AWS. Create a file, called middleware-aws.js. We now call the required libraries and configure AWS IoT. You can write this code:

You should change the values for keyPath, certPath, caPath, and region to those for AWS IoT.

We also run a web server using Express on port 3000:

Next, we listen for the connect event from AWS IoT. Once the middleware application is connected to AWS IoT, we request sensor data from Contiki-NG every three seconds. For testing, I request data from Contiki-NG with the IPv6 address [fd00::212:4b00:797:6083]. You can change it. You also can change mydeviceId:

Last, we can subscribe to the contiki-ng-sensor channel:

Save all code.

Next, we will test this project.