Communicating between Python and .NET Core with Boost Interprocess

To see if I could, I put together a cross communication library for .Net Core and Python applications using Boost.Interprocess, Boost.Python, and Boost.Signals2. The goal was simple, expose the same interface for cross communication to C# and Python. The approach taken was to use the condition example and edit it to expose to the different languages.

Shared Definitions

First I need to create the objects to make the interface. There are four files making up these objects:

  • shm_remove.hpp – just a lifecycle object to clear the shared buffer when it is destructed
  • TraceQueue.hpp – The shared memory object
  • SharedMemoryConsumer.hpp – The subscriber to the shared memory data
  • SharedMemoryProducer.hpp – The publisher for the shared memory data

These objects comprise the core interface of the shared memory provider. Now, the memory providers need to be exposed to multiple languages. There are different ways to do this and I decided to do it by hand. I should point out SWIG is my usual approach to this task, however, in this instance it seemed easy enough to do it by hand.

Boost Python

To expose the python code, I needed to create a few classes to expose the interface definitions to Boost.Python. The two classes are:

  • PythonSharedMemoryConsumer.hpp – The python interface for the SharedMemoryConsumer
  • PythonModule.cpp¬† – The file that exposes the module to python

These two classes combine to expose the files to python and can be used in a python script by just importing the shared library.

.NET Core

With the python portion complete, I needed to expose the shared memory objects to CSharp. This is easy enough to do by hand if you expose the classes to be used by PInvoke. To accomplish this, I only needed three files:

  • NetCoreSharedMemoryProducer.hpp – The .NET Core version of the publisher
  • NetCoreSharedMemoryConsumer.hpp – The .NET Core version of the consumer
  • NetCoreModule.cpp – The source file exposing the interfaces for PInvoke

 

Now we need to call that code from C# using PInvoke Interop

 

Generate Protocol Buffers on build with CMake

Just to see if it was possible on my current project, I tried to generate C++ code files from their .proto definitions whenever CMake ran. To do this, I added a few lines to the CMakeLists.txt file of the project. The idea is to use execute_process to call protoc and generate the files in the appropriate folder in the solution.

First, file(GLOB …) is used to set all of the .proto files into an iterable variable. Then, variables are setup for the proto_path and cpp_out variables.

After that, the files variable is looped and for each of the files we use execute_process to invoke protoc and generate the .pb.h and .pb.cc files.

Finally, we want to add the .pb.h and .pb.cc files to a variable for the final build. To do so, use file(GLOB …) again to search for all appropriate files.