Update README and add CHANGELOG (#46)

* Update README

* Add changelog

* Remove extra CONTRIBUTING and rename license

* Add reference examples

* Add link to memory requirements

Co-authored-by: Archit Aggarwal <[email protected]>
Co-authored-by: RichardBarry <[email protected]>

Author: 3 people

CHANGELOG.md

@@ -0,0 +1,6 @@
+# Changelog for coreMQTT Agent Library
+
+## v1.0.0 (April 2021)
+
+This is the first release of the coreMQTT Agent library in this repository.
+

CONTRIBUTING.md

@@ -1,11 +1,10 @@
-## MQTT Agent - Using coreMQTT
+## coreMQTT Agent Library
 
-Note:  The MQTT agent and associated example project are functional but not yet complete. Be aware the agent does not yet comply with our code quality standards and is not yet fully tested. There is a chance its APIs will change before its official first release.  Feedback, suggestions and comments are welcome on the [FreeRTOS support forum](https://forums.freertos.org).
+The coreMQTT Agent library is a high level API that adds thread safety to the [coreMQTT](https://github.com/FreeRTOS/coreMQTT) library. The library provides thread safe equivalents to the coreMQTT's APIs, greatly simplifying its use in multi-threaded environments. The coreMQTT Agent library manages the MQTT connection by serializing the access to the coreMQTT library and reducing implementation overhead (e.g., removing the need for the application to repeatedly call to `MQTT_ProcessLoop`). This allows your multi-threaded applications to share the same MQTT connection, and enables you to design an embedded application without having to worry about coreMQTT thread safety.
 
-[coreMQTT](https://github.com/FreeRTOS/coreMQTT) is an MIT licensed open source C MQTT client library for microcontrollers and small microprocessor based IoT devices. It’s design is intentionally simple to ensure it has no dependency on any other library or operating system, and to better enable static analysis including [memory safety proofs](https://www.freertos.org/2020/02/ensuring-the-memory-safety-of-freertos-part-1.html). That simplicity and lack of operating system dependency (coreMQTT does not require multithreading at all) means coreMQTT does not build thread safety directly into its implementation. Instead thread safety must be provided by higher level software. This labs project implements a coreMQTT extension that provides that higher level functionality in the form of an MQTT agent (or MQTT daemon). While the implementation demonstrated here is currently specific to FreeRTOS, there are not many dependencies on FreeRTOS, meaning the implementation can easily be adapted for use with other operating systems.
+This library has gone through code quality checks including verification that no function has a [GNU Complexity](https://www.gnu.org/software/complexity/manual/complexity.html) score over 8, and checks against deviations from mandatory rules in the [MISRA coding standard](https://www.misra.org.uk/MISRAHome/MISRAC2012/tabid/196/Default.aspx).  Deviations from the MISRA C:2012 guidelines are documented under [MISRA Deviations](MISRA.md). This library has also undergone both static code analysis from [Coverity static analysis](https://scan.coverity.com/), and validation of memory safety through the [CBMC automated reasoning tool](https://www.cprover.org/cbmc/).
 
-## Getting started
-The [documentation page](https://freertos.org/mqtt/mqtt-agent-demo.html) for this repository contains information on the MQTT agent and the contained demo project.
+See memory requirements for this library [here](https://freertos.org/Documentation/api-ref/coreMQTT-Agent/docs/doxygen/output/html/index.html#core_mqtt_agent_memory_requirements).
 
 ## Cloning this repository
 This repo uses [Git Submodules](https://git-scm.com/book/en/v2/Git-Tools-Submodules) to bring in dependent components.
@@ -24,14 +23,82 @@ If you have downloaded the repo without using the `--recurse-submodules` argumen
 git submodule update --init --recursive
 ```
 
+## coreMQTT Agent Library Configurations
+
+The MQTT Agent library uses the same `core_mqtt_config.h` configuration file as coreMQTT, with the addition of configuration constants listed at the top of [core_mqtt_agent.h](source/include/core_mqtt_agent.h) and [core_mqtt_agent_command_functions.h](source/include/core_mqtt_agent_command_functions.h). Documentation for these configurations can be found [here](https://freertos.org/Documentation/api-ref/coreMQTT-Agent/docs/doxygen/output/html/core_mqtt_agent_config.html).
+
+To provide values for these configuration values, they must be either:
+* Defined in `core_mqtt_config.h` used by coreMQTT
+**OR**
+* Passed as compile time preprocessor macros
+
+## Building the Library
+
+You can build the MQTT Agent source files that are in the [source](source/) directory, and add [source/include](source/include) to your compiler's include path. Additionally, the MQTT Agent library requires the coreMQTT library, whose files follow the same `source/` and `source/include` pattern as the agent library; its build instructions can be found [here](https://github.com/FreeRTOS/coreMQTT#building-the-library).
+
+If using CMake, the [mqttAgentFilePaths.cmake](mqttAgentFilePaths.cmake) file contains the above information of the source files and the header include path from this repository. The same information is found for coreMQTT from `mqttFilePaths.cmake` in the [coreMQTT submodule](source/dependency/).
+
+For a CMake example of building the MQTT Agent library with the `mqttAgentFilePaths.cmake` file, refer to the `coverity_analysis` library target in [test/CMakeLists.txt](test/CMakeLists.txt) file.
+
+## Building Unit Tests
+
+### Checkout CMock Submodule
+
+To build unit tests, the submodule dependency of CMock is required. Use the following command to clone the submodule:
+```
+git submodule update --checkout --init --recursive test/unit-test/CMock
+```
+
+### Unit Test 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 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. (Make sure that the **CMock** submodule is cloned as described [above](#checkout-cmock-submodule))
+
+1. Run the *cmake* command: `cmake -S test -B build`
+
+1. Run this command to build the library and unit tests: `make -C build all`
+
+1. The generated test executables will be present in `build/bin/tests` folder.
+
+1. Run `cd build && ctest` to execute all tests and view the test run summary.
+
+## Reference examples
+
+Please refer to the demos of the MQTT Agent library in the following locations for reference examples on FreeRTOS platforms:
+
+| Location |
+| :-: |
+| [coreMQTT Agent Demos](https://github.com/FreeRTOS/coreMQTT-Agent-Demos) |
+| [FreeRTOS/FreeRTOS](https://github.com/FreeRTOS/FreeRTOS/tree/main/FreeRTOS-Plus/Demo/coreMQTT_Windows_Simulator/MQTT_Multitask) |
+
+
+## Documentation
+
+The MQTT Agent API documentation can be found [here](https://freertos.org/Documentation/api-ref/coreMQTT-Agent/docs/doxygen/output/html/index.html).
+
+## Generating documentation
+
+The Doxygen references were created using Doxygen version 1.8.20. To generate the
+Doxygen pages yourself, please run the following command from the root of this repository:
+
+```shell
+doxygen docs/doxygen/config.doxyfile
+```
+
 ## Getting help
-You can use your Github login to get support from both the FreeRTOS community and directly from the primary FreeRTOS developers on our [active support forum](https://forums.freertos.org).  The [FAQ](https://www.freertos.org/FAQ.html) provides another support resource.
+You can use your Github login to get support from both the FreeRTOS community and directly from the primary FreeRTOS developers on our [active support forum](https://forums.freertos.org). You can find a list of [frequently asked questions](https://www.freertos.org/FAQ.html) here.
 
-## Security
+## Contributing
 
-See [CONTRIBUTING](CONTRIBUTING.md#security-issue-notifications) for more information.
+See [CONTRIBUTING.md](./.github/CONTRIBUTING.md) for information on contributing.
 
 ## License
 
-This library is licensed under the MIT License. See the [LICENSE](LICENSE.md) file.
-
+This library is licensed under the MIT License. See the [LICENSE](LICENSE) file.