Demo of a Fortran code communicating through a socket with a client

This code has moved to.

I just leave the Readme here.

Purpose of this repo

I wanted to be able to make a Fortran code communicate with an other program. Sockets were the simplest solution to achieve this. Being no Fortran programmer, I struggled to figure out how to do it. I was expecting to find some sort of example code on the web but I failed to. The web contains many examples of server/client programming in C and higher level languages. I was not able to find such an example in Fortran. So, now that I achieved my goal, I put a simple example on the web in the hope that this may help people out there.

Difficulties

Server/client communications is part of the basic training of a student in computer science at master level. Usually, this is put into practice in C or some other higher level language (usually in Python these days).

I am a C programmer (and other languages) but I am no Fortran programmer. So the biggest difficulty turned out for me to understand the equivalence between Fortran types and C types, and how to call (C) system functions passing the correctly typed parameters in the Fortran code.

The content of this repo

This repo contains:

• server.f90: a Fortran code that acts as a server in a socket based server/client communication.
• client.c: a C code that acts as a client in a socket based server/client communication.
• str2int.f90: a utility Fortran subroutine to convert a string into an integer value.
• Makefile: to create the executables, server and client.

Usage

• git clone https://github.com/ph-preux/sockets-in-Fortran.git
• cd sockets-in-Fortran
• make This should create two executable files, one named server the second one named client
• ./server
• in an other window, type ./client There is goes: the two are exchanging a couple of mundanities and stop.

Feedback

If you find some bug, or if you can provide a better coded source, or a more portable code, please email me.

Ack

While developing this demo, I benefited from a couple of helps:

• a client/server example in C
• an other client/server example in C
• a client/server example in Fortran

Moreover, Luke Rodgers proposed me to use a module to define character strings functions instead of declaring them in server.f90. The idea is to use the c_interface_module.f90. It is pretty easy to update server.f90 to use it, so I let the interested reader do it.