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Prepare your development environment

This document describes how to prepare your development environment to use the Microsoft Azure IoT device SDK for C. It describes preparing a development environment in Windows using Visual Studio and in Linux.

Set up a Windows development environment

  • Install Visual Studio 2017. You can use the Visual Studio Community Free download if you meet the licensing requirements. (Visual Studio 2015 is also supported.)

Be sure to include Visual C++ and NuGet Package Manager.

  • Install git. Confirm git is in your PATH by typing git version from a command prompt.

  • Install CMake. 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 yyyy-mm-dd format.

  • Clone the latest release of SDK to your local machine using the tag name you found:
git clone -b <yyyy-mm-dd> --recursive https://github.com/Azure/azure-iot-sdk-c.git

The --recursive argument instructs git to clone other GitHub repos this SDK depends on. Dependencies are listed here.

Build a sample application without building the SDK

To quickly build one of our sample applications, open the corresponding 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. As part of the build, NuGet Package Manager will download packages for dependencies so you don't have to build the entire SDK. See windows\packages.config for the list of packages that will be downloaded.

Build the C SDK in Windows

In some cases, you may want to build the SDK locally for development and testing purposes. First, take the following steps to generate project files:

  • Open a "Developer Command Prompt for VS2015" 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 14 2015" .. ## For Visual Studio 2015
# or
  cmake .. -G "Visual Studio 15 2017" .. ## For Visual Studio 2017

This builds x86 libraries. To build for x64 for Visual Studio 2015, modify the cmake generator argument: cmake .. -G "Visual Studio 14 2015 Win64" or for Visual Studio 2017, cmake .. -G "Visual Studio 15 2017 Win64"

If project generation completes successfully, you should 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 14 2015" -Duse_amqp=OFF ..

Also, you can build and run unit tests:

cmake -G "Visual Studio 14 2015" -Drun_unittests=ON ..
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.

Using OpenSSL in the SDK

For TLS operations, by default the C-SDK uses Schannel on Windows Platforms. You can use OpenSSL instead on Windows if you desire. NOTE: this configuration presently receives only basic manual testing and does not have gated e2e tests.

IMPORTANT SECURITY NOTE WHEN USING OPENSSL ON WINDOWS
You are responsible for updating your OpenSSL dependencies as security fixes for it become available. Schannel on Windows is a system component automatically serviced by Windows Update. OpenSSL on Linux is updated by Linux packaging mechanisms, such as apt-get on Debian based distributions. Shipping the C-SDK on Windows using OpenSSL means you are responsible for getting updated versions of it to your devices.

OpenSSL binaries that the C-SDK depends on are ssleay32 and libeay32. To enable OpenSSL to be used on Windows, you need to

  • Obtain OpenSSL binaries. There are many ways to do this, but one of the easier ways is to:

    • Open the appropriate developer command prompt you plan on building the C-SDK from.
    • Install vcpkg, a Microsoft tool that helps you manage C and C++ libraries.
    • Run .\vcpkg install openssl to obtain the required OpenSSL binaries.
    • Make note of the directory that OpenSSL has been installed to by vcpkg, e.g. C:\vcpkgRoot\vcpkg\packages\openssl_x86-windows.
  • Make the C-SDK link against these OpenSSL binaries instead of the default Schannel.

    • Regardless of how you obtained OpenSSL binaries, set environment variables to point at its root directory. Be careful there are no leading spaces between the = and directory name as cmake's errors are not always obvious.

       set OpenSSLDir=C:\vcpkgRoot\vcpkg\packages\openssl_x86-windows
       set OPENSSL_ROOT_DIR=C:\vcpkgRoot\vcpkg\packages\openssl_x86-windows
    • Build the SDK to include OpenSSL. The key difference from the typical flow is the inclusion of the -Duse_openssl:BOOL=ON option when invoking cmake.

      cd azure-iot-sdk-c
      mkdir cmake
      cd cmake
      cmake -Duse_openssl:BOOL=ON ..
      cmake --build . -- /m /p:Configuration=Release

Building samples and your application should be the same as using the default Schannel at this point.

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
  • Verify that CMake is at least version 2.8.12:

    cmake --version

    For information about how to upgrade your version of CMake to 3.x on Ubuntu 14.04, read How to install CMake 3.2 on Ubuntu 14.04?.

  • Verify that gcc is at least version 4.4.7:

    gcc --version

    For information about how to upgrade your version of gcc on Ubuntu 14.04, read How do I use the latest GCC 4.9 on Ubuntu 14.04?.

  • 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 yyyy-mm-dd format.

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

    git clone -b <yyyy-mm-dd> --recursive https://github.com/Azure/azure-iot-sdk-c.git

    The --recursive argument instructs git to clone other GitHub repos this SDK depends on. Dependencies are listed here.

Build the C SDK in 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

Note: Any samples you built 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 yyyy-mm-dd format.

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

    git clone -b <yyyy-mm-dd> --recursive https://github.com/Azure/azure-iot-sdk-c.git

    The --recursive argument instructs git to clone other GitHub repos this SDK depends on. Dependencies are listed here.

Upgrade CURL on Mac OS

  1. Install the latest version of curl macosx:~ username$ brew install curl

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.

  1. Force link updates:
brew link curl --force
  1. 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"

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

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

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:

cmake -Duse_amqp=OFF ..

Also, you can build and run unit tests:

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

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".

[DEPRECATED: Set up a Windows Embedded Compact 2013 development environment

WINDOWS EMBEDDED COMPACT 2013 RECEIVES MINIMAL SUPPORT FROM AZURE IOT SDK. In particular please be aware:

  • No new features will be added to WEC.
  • The only supported protocol is HTTPS. Popular protocols like AMQP and MQTT, both over TCP directly and over WebSockets, are not and will not be supported.
  • HTTPS over proxy is not supported.
  • Developers may want to evaluate Windows 10 IoT Core, which has much broader Azure IoT SDK support.

SETUP INSTRUCTIONS FOR WINDOWS EMBEDDED COMPACT 2013

  • Install Visual Studio 2015. You can use the Visual Studio Community Free download if you meet the licensing requirements.

    Be sure to include Visual C++ and NuGet Package Manager.

  • Install Application Builder for Windows Embedded Compact 2013 for Visual Studio 2015

  • Install Toradex Windows Embedded Compact 2013 SDK or your own SDK.

  • Install git. Confirm git is in your PATH by typing git version from a command prompt.

  • Install CMake. 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 yyyy-mm-dd format.

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

    git clone -b <yyyy-mm-dd> --recursive https://github.com/Azure/azure-iot-sdk-c.git

    The --recursive argument instructs git to clone other GitHub repos this SDK depends on. Dependencies are listed here.

If you installed a different SDK please check azure-iot-sdk-c\build_all\windowsce\build.cmd and replace:

set SDKNAME=TORADEX_CE800
set PROCESSOR=arm

with a reference to the name of the SDK and the processor architecture (arm/x86) you plan to use.

Verify your environment

You can build the Windows samples to verify that your environment is set up correctly.

  • Open a "Developer Command Prompt for VS2015".
  • Navigate to the build_all\windowsce folder in your local copy of the repository.
  • Run the following command:
build

This script uses CMake to create a folder called "cmake_ce8" in your home directory and generates in that folder a Visual Studio solution called azure_iot_sdks.sln. The script will then proceed to build the HTTP sample.

Note: you will not be able to run the samples until you configure them with a valid IoT hub device connection string. For more information, see running a C sample application on Windows Embedded Compact 2013 on a Toradex module.

To view the projects and examine the source code, open the azure_iot_sdks.sln solution file in Visual Studio.

You can use one of the sample applications as a template to get started when you are creating your own client applications.

Sample applications

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

-Simple samples for the device SDK

-Samples using the serializer library

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