Fast MATLAB-C Communication Sockets

The project allows for fast and efficient communication between MATLAB and an external C/C++-based application using custom socket interface. Current implementation contains only Windows sockets.

The communication is handled by a server socket being maintained in a CPP-side, and MATLAB connecting to it when needed. Majority of code is shared between client and server side, which helps remove errors associated with wrong handling of data on both sides.

Getting Started

These instructions will get you a copy of the project up and running on your local machine for development and testing purposes.

This project's code is available on GitHub.

Prerequisites

MATLAB 2017a+

C/C++ compiler:

• Microsoft Visual Studio 2015+ (recommended for Windows)

• GCC (automatic compilation not implemented), available from MinGW

Make tool (optional) for automatic compilation available as a part of MSYS from MinGW

For C/C++ compiler make sure that the environments are available from command line when you want to compile the source:

• Visual Studio: cl --version

• GCC: gcc --version

Use src/startcl.bat to launch 64-bit Visual Studio environment. Requires VS140COMNTOOLS global variable, which should be set during Visual Studio installation.

Compiling Server side

Using Make

Assuming the compilers are set up and make tool is available, the following code should run without errors:

matlab_c_sockets>cd src
matlab_c_sockets/src>make all

This should create directories for object files and executables.

Without Make

The command sequence can be executed manually:

matlab_c_sockets>mkdir bin
matlab_c_sockets>cd src
matlab_c_sockets/src>cl /Fe../bin/cpp_server.exe cpp_server.cpp socket_api.cpp socket.cpp crossplatform_win.cpp /O2 /EHsc /MT

Compiling MATLAB side

Run the src/makeClient.m from MATLAB IDE. It should create matlab_client.mexw64 file in the parent directory.

Running the test

Start the server by either double-clicking on the executable file in the bin folder, or running it from command line:

matlab_c_sockets>cd bin
matlab_c_sockets/bin>cpp_server.exe

Run testClient.m script from MATLAB IDE. The script connects to the server, requests some data, and closes the connection.

Adding a new communication

In this section is described where the code needs to be changed and edited to make a novel communication between MATLAB and C++.

1. Specify the structures that you wish to send from MATLAB and to MATLAB in src/socket_api.h around line 106 analogous to mjRequestSquares and mjReplySquares. One for sending from MATLAB, and another to send data from CPP-server.
2. Write how the structures should be handled on the server and client side. Use
   • mjtResult mj_request_squares(const mjRequestSquares* rqs, mjReplySquares* res) (client)
   • mjtResult mj_respond_squares(void) (server) in src/socket_api.cpp as an example. Do not forget to declare them in src/socket_api.h!
3. For proper response to a client request, add a new message code to mjtComCode (line 40 of src/socket_api.h). Add handling of this message to mjtResult mj_respond(void) in src/socket_api.cpp line 372.
4. Write a MATLAB wrapper of the input in src/matlab_client.cpp analogous to mxArray* getsquares(const mxArray* pin) fucntion. It rearranges data from the MATLAB style into a structure and passes it to the client-side function.
5. Add handling of a new input keyword to MATLAB client same as in lines 264-265 and write a description into const char* _help (line 176).
6. Recompile the MATLAB and the server side using src/makeClient.m and make, and it should be ready to use.

Using on different computers and changing port

This software allows communication between client and server on different computers. When cpp_server starts, it prints IP address and port to which to connect to. If connecting on the same computer, it can be omitted on MATLAB side: matlab_client.mexw64 allows 'connect' without additional arguments, see 'help'.

Port can be passed to CPP server as a second argument: cpp_server.exe 44401. Connection to it on the same machine from MATLAB: matlab_client('connect', '', '44401'). Note that the port is passed as a char array.

Authors

• Emo Todorov - Initial work - http://homes.cs.washington.edu/~todorov/

• Anton Sobinov - Organization and restructuring of code - nishbo

License

This project is licensed under the Apache 2.0 License - see the LICENSE.md file for details.