commschamp/cc.demo3.commsdsl

Third demo protocol for commsdsl and CommsChampion ecosystem

Overview

This is a demo protocol for CommsChampion Ecosystem. It demonstrates a protocol that reports its version in the payload of the first Connect message, and all subsequent messages are treated as having the reported version.

The protocol is defined in the schema file using CommsDSL. The commsds2comms code generator from commsdsl project is used to generate C++11 code of the protocol implementation.

This project also contains two example applications (client + server), which demonstrate exchange of the protocol messages over TCP/IP link.

Protocol

The contents of the protocol messages demonstrate existence of the fields based on the protocol version information, reported in the payload of one of the messages.

The transport framing is

SYNC (2 bytes) | SIZE (2 bytes) | ID (1 byte) | PAYLOAD | CHECKSUM (2 bytes)

where

• SYNC is synchronization bytes, expected to be 0xab 0xcd.
• SIZE is remaining length (including CHECKSUM)
• ID is numeric ID of the message.
• PAYLOAD is message payload.
• CHECKSUM is 16 bit CRC-CCITTT checksum of SIZE | ID | PAYLOAD bytes.

The code generators from the commsdsl repository generate full CMake projects. Some of these generated projects are hosted as separate repositories that can be viewed and used independently.

• cc.demo3.generated - Protocol definition
• cc.demo3_protocol.cc_tools_plugin - Protocol plugin for the CommsChampion Tools.

Examples

The client reads requested version value from standard input. Once proper version is entered, it prepares and sends Connect message to the server to report protocol version, then immediatelly sends Msg1 message adjusted to have fields relevant to the version.

The server records protocol version received in Msg1 message and prints values of received 'Msg1` message's fields. No message is sent back to the client.

License

Please read License section from commsdsl project.

How to Build

This project uses CMake as its build system. Please open main CMakeLists.txt file and review available options as well as mentioned available parameters, which can be used in addition to standard ones provided by CMake itself, to modify the default build.

This project also has external dependencies, it requires an access to the COMMS Library and code generators from commsdsl projects. These dependencies are expected to be built independenty and access to them provided via standard CMAKE_PREFIX_PATH and/or CMAKE_PROGRAM_PATH (for the binaries of the code generators). There are also scripts ( script/prepare_externals.sh for Linux and script/prepare_externals.bat for Windows) which can help in preparation of these dependencies. They are also used in configuration of the github actions.

The project's cmake configuration options allow building bindings to other high level programming languages using swig and emscripten, see relevant commsdsl's documentation pages for details.

The example applications use Boost to parse their command line parameters as well as manage their asynchronous I/O. In case Boost libraries are not installed in expected default location (mostly happens on Windows systems), use variables described in CMake documentation to help CMake find required libraries and headers. It is recommended to use -DBoost_USE_STATIC_LIBS=ON parameter to force linkage with static Boost libraries.

Linux Build

$> cd /source/of/this/project
$> mkdir build && cd build
$> BUILD_DIR=$PWD CC=gcc CXX=g++ COMMON_INSTALL_DIR=$PWD/install COMMON_BUILD_TYPE=Release ../script/prepare_externals.sh
$> cmake .. -DCMAKE_BUILD_TYPE=Release -DCMAKE_INSTALL_PREFIX=$PWD/install -DCMAKE_PREFIX_PATH=$PWD/install
$> make install

Windows Build

$> cd C:\source\of\this\project
$> mkdir build && cd build
$> set BUILD_DIR=%cd%
$> set GENERATOR="NMake Makefiles"
$> set QTDIR=C:\Qt\5.15.2
$> set COMMON_INSTALL_DIR=%cd%/install
$> ..\script\prepare_externals.bat
$> cmake .. -G "NMake Makefiles" -DCMAKE_BUILD_TYPE=Release ^
    -DCMAKE_INSTALL_PREFIX=%cd%/install -DCMAKE_PREFIX_PATH=%cd%\install ^
    -DBOOST_ROOT="C:\Libraries\boost_1_65_1" -DBoost_USE_STATIC_LIBS=ON
$> nmake install

Supported Compilers

Please read Supported Compilers info from commsdsl project.

How to Build and Use Generated Code

Please read the Generated CMake Project Walkthrough documentation page for details on the generated project internals.

The release artifacts contain doxygen generated documentation of the protocol definition.

Contact Information

For bug reports, feature requests, or any other question you may open an issue here in github or e-mail me directly to: [email protected]. I usually respond within 24 hours.