MQTT Client Library

This repository contains an ISO C90 compliant MQTT client library designed for embedded platforms.

MQTT Config File

The MQTT client library exposes build configuration macros that are required for building the library. A list of all the configurations and their default values are defined in core_mqtt_config_defaults.h. To provide custom values for the configuration macros, a custom config file named core_mqtt_config.h can be provided by the application to the library.

By default, a core_mqtt_config.h custom config is required to build the library. To disable this requirement and build the library with default configuration values, provide MQTT_DO_NOT_USE_CUSTOM_CONFIG as a compile time preprocessor macro.

Thus, the MQTT library can be built by either:

• Defining a core_mqtt_config.h file in the application, and adding it to the include directories list of the library
  OR
• Defining the MQTT_DO_NOT_USE_CUSTOM_CONFIG preprocessor macro for the library build.

Building the Library

The mqttFilePaths.cmake file contains the information of all source files and the header include path required to build the MQTT library.

As mentioned in the previous section, either a custom config file (i.e. core_mqtt_config.h) OR MQTT_DO_NOT_USE_CUSTOM_CONFIG macro needs to be provided to build the MQTT library.

For a CMake example of building the MQTT library with the mqttFilePaths.cmake file, refer to the coverity_analysis library target in test/CMakeLists.txt file.

Building Unit Tests

Platform Prerequisites

• For building the library, CMake 3.13.0 or later and a C90 compiler.
• For running unit tests, Ruby 2.0.0 or later is additionally required for the CMock test framework (that we use).
• For running the coverage target, gcov and lcov are additionally required.

Steps to build Unit Tests

1. Go to the root directory of this repository.

2. Run the cmake command: cmake -S ../test -B build -DBUILD_CLONE_SUBMODULES=ON

3. Run this command to build the library and unit tests: make -C build all

4. The generated test executables will be present in build/bin/tests folder.

5. Run ctest to execute all tests and view the test run summary.

Reference examples

The AWS IoT Embedded C-SDK repository contains demos of using the MQTT client library here on a POSIX platform. These can be used as reference examples for the library API.

Generating documentation

The Doxygen references were created using Doxygen version 1.8.20. To generate the Doxygen pages, please run the following command from the root of this repository:

doxygen docs/doxygen/config.doxyfile