MQTT File Streams library

In AWS IoT, a stream is a publicly addressable resource that is an abstraction for a list of files that can be transferred to an IoT device. Using MQTT file streams library, files from a stream can be transfer to an IoT device. The file is transferred using MQTT protocol. It supports both JSON and CBOR format to send requests and receive data.

More information about streams and MQTT based file delivery can be found here

MQTT File Streams Config File

The MQTT file streams 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 MQTTFileDownloader_defaults.h. To provide custom values for the configuration macros, a custom config file named MQTTFileDownloader_config.h can be provided by the application to the library.

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

Thus, the MQTT library can be built by either:

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

MQTT File Streams library workflow

Building MQTT File Streams library

Dependencies

The MQTT streams library depend on the following two libraries for encoding/decoding GetStream Request and Data blocks.

1. tinyCBOR
2. coreJSON

Build instructions

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

Building unit tests

Platform Prerequisites

• For running unit tests
  • C90 compiler like gcc
  • CMake 3.13.0 or later
  • Ruby 2.0.0 or later is additionally required for the Unity test framework (that we use).
• For running the coverage target, gcov is additionally required.

Steps to build Unit Tests

1. Go to the root directory of this repository.

2. Create build directory: mkdir build && cd build

3. Run cmake while inside build directory: cmake -S ../test

4. Run this command to build the library and unit tests: make all

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

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

CBMC

To learn more about CBMC and proofs specifically, review the training material here.

The test/cbmc directory contains CBMC proofs.

In order to run these proofs you will need to install CBMC and other tools by following the instructions here.

Contributing

See CONTRIBUTING.md for information on contributing.

Security

See SECURITY for more information.

License

This library is licensed under the MIT Open Source License.