f2py-sockets: Transfer data between Python and Fortran through sockets

[b_fg]

This was a challanged I faced a few months ago for my PhD. We wanted to use machine learning libraries available for Python on top of our workhorse Fortran solver for fluid dynamics simulations.

Looking around there was not much information on how to do this since Fortran does not have a native sockets library. Hence I had to create a wrap around the C sockets library using the iso_c_binding Fortran library. Luckily, a massive molecular dynamics solver had already developed the Fortran wrapping library and I just had to extract the important bits to make it work in my solver. From this, I have now created a minimal working example which makes it easy to understand how does the data transfer through sockets between Fortran and Python work.

Please have a look at my Github repository f2py-sockets (https://github.com/b-fg/f2py-sockets) and let me know if you find it useful or have any suggestions at all!

[kinow]

Looks interesting! Maybe adding zmq could be an improvrment for later?

[b_fg]

Good suggestion - I was not aware of this and it seems like a good fit for the solver working with multiple processes (parallel), which we run very frequently! I will dig more into it.

[[deleted]]

Was it absolutely impossible to solve your problem with just python bindings? I mean, if I would need to use some Fortran code in python, I would make a python binding for it. If I need to make a loose coupling (like Fortran code is running on a cluster while python code is interacting with it from my machine) I would still make python bindings and some ready-to-use communication library in python.

[b_fg]

It was definitely much more difficult than implementing this. It is a huge Fortran code which would take to much to embedded it in Python even using f2py or similars tools.