Ubuntu Telemetry Walkthrough

Using the Azure IoT C SDK on Ubuntu

This sample shows how to create a program that uses the Azure IoT SDK C package on Ubuntu apt package manager.

Setting up IoT Hub Environment

1. If you have not already, follow the instructions here to set up your IoT Hub enviornment on Azure.

2. Create a IoT Hub device and copy it's device connection string to be used later. Instructions on this can also be found in the link in step 1.

3. Make sure you have CMake, g++, and gcc installed on your development machine

   sudo apt install cmake build-essential

Install Azure IoT C SDK on Your Machine

We will use the apt package manager to download the binaries needed to build an IoT Hub client application using C.

1. Add the Azure IoT repository

   sudo apt install -y software-properties-common
   sudo add-apt-repository ppa:aziotsdklinux/ppa-azureiot
   sudo apt update

2. Install the azure-iot-sdk-c-dev package

   sudo apt install -y azure-iot-sdk-c-dev

3. If you haven't already, clone the Azure IoT C SDK repo from Github

   git clone  https://github.com/Azure/azure-iot-sdk-c.git
   cd azure-iot-sdk-c
   git submodule update --init --recursive

Create an Application

We will use iothub_ll_telemetry_sample to demonstrate compiling and running a sample.

1. Note the location where you have cloned the azure-iot-sdk-c repo. We will assume it is cloned to the home directory for convenience, but if not you can adjust the path accordingly.

   cd ~/azure-iot-sdk-c/

2. You now will use the device connection string you copied while setting up the IoT Hub Enviornment. Using your favorite text editor (we will use nano), edit the iothub_ll_telemetry_sample file.

   nano iothub_client/samples/iothub_ll_telemetry_sample/iothub_ll_telemetry_sample.c

   Find the line containing the following code...

   static const char* connectionString = "[device connection string]";

   ...and update the string between the quotations with your own device connection string.

   static const char* connectionString = "HostName=foo;DeviceID=fooDevice;SharedAccessKey=fooKey";

   Save and close the file.

3. Build the sample using cmake. First navigate to the sample folder.

   cd ~/azure-iot-sdk-c/iothub_client/samples/iothub_ll_telemetry_sample/linux/

   Then compile using cmake.

   cmake .

   Finally, build the sample.

   cmake --build .

Run the Sample Application

Once the sample application has been built using cmake, you can simply run it

./iothub_ll_telemetry_sample

Did everything work? If so, you should see approximately the following output:

Creating IoTHub Device handle
Sending message 1 to IoTHub
Sending message 2 to IoTHub
Sending message 3 to IoTHub
Sending message 4 to IoTHub
Sending message 5 to IoTHub
-> 00:07:23 CONNECT | VER: 4 | KEEPALIVE: 240 | FLAGS: 192 | USERNAME: yosephhub.azure-devices.net/testDevice/?api-version=2017-11-08-preview&DeviceClientType=iothubclient%2f1.2.10%20(native%3b%20Linux%3b%20x86_64) | PWD: XXXX | CLEAN: 0
<- 00:07:23 CONNACK | SESSION_PRESENT: true | RETURN_CODE: 0x0
The device client is connected to iothub
-> 00:07:23 PUBLISH | IS_DUP: false | RETAIN: 0 | QOS: DELIVER_AT_LEAST_ONCE | TOPIC_NAME: devices/testDevice/messages/events/property_key=property_value | PACKET_ID: 2 | PAYLOAD_LEN: 12
-> 00:07:23 PUBLISH | IS_DUP: false | RETAIN: 0 | QOS: DELIVER_AT_LEAST_ONCE | TOPIC_NAME: devices/testDevice/messages/events/property_key=property_value | PACKET_ID: 3 | PAYLOAD_LEN: 12
-> 00:07:23 PUBLISH | IS_DUP: false | RETAIN: 0 | QOS: DELIVER_AT_LEAST_ONCE | TOPIC_NAME: devices/testDevice/messages/events/property_key=property_value | PACKET_ID: 4 | PAYLOAD_LEN: 12
-> 00:07:23 PUBLISH | IS_DUP: false | RETAIN: 0 | QOS: DELIVER_AT_LEAST_ONCE | TOPIC_NAME: devices/testDevice/messages/events/property_key=property_value | PACKET_ID: 5 | PAYLOAD_LEN: 12
-> 00:07:23 PUBLISH | IS_DUP: false | RETAIN: 0 | QOS: DELIVER_AT_LEAST_ONCE | TOPIC_NAME: devices/testDevice/messages/events/property_key=property_value | PACKET_ID: 6 | PAYLOAD_LEN: 12
<- 00:07:24 PUBACK | PACKET_ID: 2
Confirmation callback received for message 1 with result IOTHUB_CLIENT_CONFIRMATION_OK
<- 00:07:24 PUBACK | PACKET_ID: 3
Confirmation callback received for message 2 with result IOTHUB_CLIENT_CONFIRMATION_OK
<- 00:07:24 PUBACK | PACKET_ID: 4
Confirmation callback received for message 3 with result IOTHUB_CLIENT_CONFIRMATION_OK
<- 00:07:24 PUBACK | PACKET_ID: 5
Confirmation callback received for message 4 with result IOTHUB_CLIENT_CONFIRMATION_OK
<- 00:07:24 PUBACK | PACKET_ID: 6
Confirmation callback received for message 5 with result IOTHUB_CLIENT_CONFIRMATION_OK
-> 00:07:24 DISCONNECT
Press any key to continue

That's it. You've compiled and run a sample using the low level (_ll_) C SDK. For more samples explore the samples folder here.