This document describes how to prepare your development environment to use the Microsoft Azure IoT device SDK for C.

Set up a Windows development environment

Install Visual Studio 2022. You can use the Visual Studio Community free download if you meet the licensing requirements. (Visual Studio 2017 and Visual Studio 2019 are also supported.)

Be sure to include Visual C++.

Install git. Confirm git is in your PATH by typing git version from a command prompt.
Install CMake, either by including it in your Visual Studio install or installing directly from CMake.org. Make sure it is in your PATH by typing cmake -version from a command prompt. CMake will be used to create Visual Studio projects to build libraries and samples.
Locate the tag name for the latest release of the SDK.

Our release tag names are date values in lts_mm_yyyy format.

Clone the latest release of SDK to your local machine using the tag name you found:

git clone -b <lts_mm_yyyy> https://github.com/Azure/azure-iot-sdk-c.git
cd azure-iot-sdk-c
git submodule update --init

>If you are using a release before 2019-04-15 then you will need to use the --recursive argument for git submodule. Otherwise it is highly recommended NOT to use --recursive as this results in poor git performance.

Building sample applications using vcpkg to build the SDK

The sample applications can be build with the help of the C SDK libraries and headers built with vcpkg. vcpkg is a package manager that facilitates building C and C++ libraries. To install the vcpkg C SDK libraries and headers, follow these steps Setup C SDK vcpkg for Windows development environment.

Note: vcpkg manager creates a directory with all the headers and generates the C SDK .lib files on your machine. If you are using Visual Studio (from 2017) the command 'vcpkg integrate install' lets Visual Studio knows where the vcpkg headers and lib directories are located. If you're using other IDEs, just add the vcpkg directories to your compiler/linker include paths.

To quickly build one of the sample applications, open the corresponding Visual Studio solution file (.sln) in Visual Studio. For example, to build the telemetry message sample, open **iothub_client\samples\iothub_ll_telemetry_sample\windows\iothub_ll_telemetry_sample.sln**.

In the sample's main source file, find the line similar to this:

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

...and replace [device connection string] with a valid device connection string for a device registered with your IoT Hub. For more information, see the samples section below.

Build the sample project.

Building the C SDK with CMake on Windows

In some cases, you may want to build the SDK locally for development and testing purposes (without using vcpkg). First, take the following steps to generate project files:

Open a "Developer Command Prompt for VS 2022" or "Developer Command Prompt for VS2019" or "Developer Command Prompt for VS2017".
Run the following CMake commands from the root of the repository:

cd azure-iot-sdk-c
mkdir cmake
cd cmake
# Either
  cmake .. -G "Visual Studio 15 2017" ## For Visual Studio 2017
# or
  cmake .. -G "Visual Studio 16 2019" -A Win32
# or
  cmake .. -G "Visual Studio 17 2022" -A Win32

This builds x86 libraries. To build for x64 for Visual Studio 2017: cmake .. -G "Visual Studio 15 2017 Win64", for Visual Studio 2019: cmake .. -G "Visual Studio 16 2019" -A x64, or for Visual Studio 2022: cmake .. -G "Visual Studio 17 2022" -A x64

When the project generation completes successfully, you will see a Visual Studio solution file (.sln) under the cmake folder. To build the SDK, do one of the following:

Open **cmake\azure_iot_sdks.sln** in Visual Studio and build it, OR
Run the following command in the command prompt you used to generate the project files:

cmake --build . -- /m /p:Configuration=Release

To build Debug binaries, use the corresponding MSBuild argument: cmake --build . -- /m /p:Configuration=Debug There are many CMake configuration options available for building the SDK. For example, you can disable one of the available protocol stacks by adding an argument to the CMake project generation command:

cmake -G "Visual Studio 15 2017" -Duse_amqp=OFF .. // same with 2017, 2019, and 2022 generator (see above)

Also, you can build and run unit tests:

cmake -G "Visual Studio 15 2017" -Drun_unittests=ON ..  // same with 2017, 2019, and 2022 generator (see above)
cmake --build . -- /m /p:Configuration=Debug
ctest -C "debug" -V

Build a sample that uses different protocols, including over WebSockets

By default the C-SDK will have web sockets enabled for AMQP and MQTT. The sample **iothub_client\samples\iothub_ll_telemetry_sample** lets you specify the protocol variable.

Unless you have a reason otherwise, we recommend you use MQTT as your protocol.

Build a sample using a specific server root certificate

By default all samples are built to handle a variety of server root CA certificates during TLS negotiation. If you would like to decrease the size of the sample, select the appropriate root certificate option during the cmake step. Follow the instructions here.

Note: Any samples you build will not work until you configure them with a valid IoT Hub device connection string. For more information, see the samples section below.

It is possible to use OpenSSL as your TLS stack instead of the default Schannel when running on Windows, although this is highly discouraged. See this document for more.

Set up a Linux development environment

This section describes how to set up a development environment for the C SDK on Ubuntu. CMake will create makefiles and make will use them to compile the C SDK source code using the gcc compiler.

Make sure all dependencies are installed before building the SDK. For Ubuntu, you can use apt-get to install the right packages:

sudo apt-get update

sudo apt-get install -y git cmake build-essential curl libcurl4-openssl-dev libssl-dev uuid-dev ca-certificates

NOTE: If you are planning to use HTTP other than with the default OpenSSL, (i.e., wolfSSL or mbedTLS), you must configure cURL before installation.

Download the latest cURL.
See curl documentation to use the wolfSSL or mbedTLS option for configuration.
Configure, build, and install cURL.

Verify that CMake is at least version 2.8.12:

cmake --version

Verify that gcc is at least version 4.4.7:

gcc --version

Locate the tag name for the latest release of the SDK.

Our release tag names are date values in lts_mm_yyyy format.
Clone the latest release of SDK to your local machine using the tag name you found:

git clone -b <lts_mm_yyyy> https://github.com/Azure/azure-iot-sdk-c.git
cd azure-iot-sdk-c
git submodule update --init

>If you are using a release before 2019-04-15 then you will need to use the --recursive argument for git submodule. Otherwise it is highly recommended NOT to use --recursive as this results in poor git performance.

Build the C SDK on Linux

To build the SDK:

cd azure-iot-sdk-c
mkdir cmake
cd cmake
cmake ..
cmake --build .  # append '-- -j <n>' to run <n> jobs in parallel

To build Debug binaries, add the corresponding CMake option to the project generation command above, e.g.:

cmake -DCMAKE_BUILD_TYPE=Debug ..

There are many CMake configuration options available for building the SDK. For example, you can disable one of the available protocol stacks by adding an argument to the CMake project generation command:

cmake -Duse_amqp=OFF ..

Also, you can build and run unit tests:

cmake -Drun_unittests=ON ..
cmake --build .
ctest -C "debug" -V

Build a sample that uses different protocols, including over WebSockets

By default the C-SDK will have web sockets enabled for AMQP and MQTT. The sample **iothub_client\samples\iothub_ll_telemetry_sample** lets you specify the protocol variable.

Unless you have a reason otherwise, we recommend you use MQTT as your protocol.

Build a sample using a specific server root certificate

By default all samples are built to handle a variety of server root CA certificates during TLS negotiation. If you would like to decrease the size of the sample, select the appropriate root certificate option during the cmake step. Follow the instructions here.

Note: Any samples you build will not work until you configure them with a valid IoT Hub device connection string. For more information, see the samples section below.

Set up a macOS (Mac OS X) development environment

This section describes how to set up a development environment for the C SDK on macOS. CMake will create an XCode project containing the various SDK libraries and samples.

We've tested the device SDK for C on macOS High Sierra, with XCode version 9.2.

Make sure all dependencies are installed before building the SDK. For macOS, you can use Homebrew to install the right packages:

brew update

brew install git cmake pkgconfig openssl ossp-uuid

Verify that CMake is at least version 2.8.12:

cmake --version

Patch CURL to the latest version available.

The minimum version of curl required is 7.56, as recent previous versions presented critical failures. To upgrade see "Upgrade CURL on Mac OS" steps below.
Locate the tag name for the latest release of the SDK.

Our release tag names are date values in lts_mm_yyyy format.
Clone the latest release of SDK to your local machine using the tag name you found:

git clone -b <lts_mm_yyyy> https://github.com/Azure/azure-iot-sdk-c.git
cd azure-iot-sdk-c
git submodule update --init

>If you are using a release before 2019-04-15 then you will need to use the --recursive argument for git submodule. Otherwise it is highly recommended NOT to use --recursive as this results in poor git performance.

Upgrade CURL on Mac OS

Install the latest version of curl
{macosx:~}

At the end of the installation you will get this info:

Error: Failed to create /usr/local/opt/curl ... ==> Caveats This formula is keg-only, which means it was not symlinked into /usr/local, because macOS already provides this software and installing another version in parallel can cause all kinds of trouble. ... ==> Summary 🍺 /usr/local/Cellar/curl/7.58.0: 415 files, 3MB
Save the path "/usr/local/Cellar/curl/7.58.0", this is where the library and headers were actually installed.

2. Force link updates:

brew link curl –force
3. Set DYLD_LIBRARY_PATH:

export DYLD_LIBRARY_PATH="/usr/local/Cellar/curl/7.58.0/lib:$DYLD_LIBRARY_PATH"
Make sure the path above matches the one saved on step 1.

### Build the C SDK

If you upgraded CURL, make sure to set DYLD_LIBRARY_PATH each time you open a new shell.

The next command assumes curl was saved on the path below mentioned ("keg install").

Make sure you use the path as informed by `brew` when curl was upgraded.

export DYLD_LIBRARY_PATH="/usr/local/Cellar/curl/7.58.0/lib:$DYLD_LIBRARY_PATH"
Next you can either build the C SDK with CMake directly, or you can use CMake to generate an XCode project.

#### Building the C SDK with CMake directly

```Shell

cd azure-iot-sdk-c

mkdir cmake

cd cmake

cmake -DOPENSSL_ROOT_DIR:PATH=/usr/local/opt/openssl ..

cmake --build . # append '-- -j <n>' to run <n> jobs in parallel

To build Debug binaries, add the corresponding CMake option to the project generation command above, e.g.:

cmake -DOPENSSL_ROOT_DIR:PATH=/usr/local/opt/openssl -DCMAKE_BUILD_TYPE=Debug ..

There are many CMake configuration options available for building the SDK. For example, you can disable one of the available protocol stacks by adding an argument to the CMake project generation command:

```Shell cmake -Duse_amqp=OFF ..
</blockquote>

Also, you can build and run unit tests:

<blockquote>```Shell

cmake -Drun_unittests=ON ..

cmake --build .

ctest -C "debug" -V

Build a sample that uses different protocols, including over WebSockets

By default the C-SDK will have web sockets enabled for AMQP and MQTT. The sample **iothub_client\samples\iothub_ll_telemetry_sample** lets you specify the protocol variable.

Unless you have a reason otherwise, we recommend you use MQTT as your protocol.

Build a sample using a specific server root certificate

By default all samples are built to handle a variety of server root CA certificates during TLS negotiation. If you would like to decrease the size of the sample, select the appropriate root certificate option during the cmake step. Follow the instructions here.

Note: Any samples you build will not work until you configure them with a valid IoT Hub device connection string. For more information, see the samples section below.

Generate an XCode Project

To generate the XCode project:

cd azure-iot-sdk-c
mkdir cmake
cd cmake
cmake -G Xcode ..

All of the CMake options described above will work for XCode generation as well.

When project generation completes you will see an XCode project file (.xcodeproj) under the cmake folder. To build the SDK, open **cmake\azure_iot_sdks.xcodeproj** in XCode and use XCode's build and run features.

Note: Until Mac updates the Curl library to version to 7.58 or greater it will also be necessary to modify your XCode project file (.xcodeproj) to replace all the lines that read LIBRARY_SEARCH_PATHS = ""; with LIBRARY_SEARCH_PATHS = "/usr/local/Cellar/curl/7.58.0/lib";

The example above assumes curl 7.58 has been compiled and saved into /usr/local/Cellar/curl/7.58.0. For more details please see section "Upgrade CURL on Mac OS".

Sample applications

This repository contains various C sample applications that illustrate how to use the Azure IoT device SDK for C:

-Samples for the device SDK

Once the SDK is building successfully you can run any of the available samples using the following (example given for a linux system):

-Edit the sample file entering the proper connection string from the Azure Portal:

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

-Navigate to the directory of the sample that was edited, build the sample with the new changes and execute the sample:

cd ./azure-iot-sdk-c/cmake/iothub_client/samples/iothub_ll_telemetry_sample
make
./iothub_ll_telemetry_sample