RE: [Caml-list] Named pipe on Windows.

[David Allsopp <dra-news@metastack.com>]

paul.lachat@edu.univ-fcomte.fr wrote:
> Hello,
>
> I need to setup communication between two Ocaml processes on Windows.
> I think that using the named pipe of Windows is the good method to do this task.

Depending on your exact needs, you can also accomplish this with anonymous pipes - use Unix.pipe (twice, if you need to communicate two ways) and pass the appropriate side of each pipe as stdin and stdout to Unix.create_process. That of course assumes that you can afford to use stdin/stdout for this. I don't think that the Unix module allows you to create inheritable handles, so I think that's the only way of passing the pipe descriptor without resorting to bindings.

> But I can't find any module for Ocaml who allow using the system call of Windows.

The traditional way is to create bindings in C for the system calls (see https://caml.inria.fr/pub/docs/manual-ocaml/intfc.html). The library you have found is certainly an example of doing this.

> I have already find this module https://opam.ocaml.org/packages/named-pipe/, but it use C,
> and I would like to avoid depending on another langage than Ocaml or software like Cygwin.

The OCaml runtime is implemented in C, so in some senses you can't avoid it! Note that Cygwin is in this context an operating system - you can bind to Windows system calls using stubs written in C and still not depend on Cygwin (if you use the Microsoft Visual C ports of OCaml, you don't even need Cygwin to compile your code). If you are using the actual Cygwin ports of OCaml, then although you can bind to Windows system calls, you shouldn't - you should use a normal Unix "file-based" pipe (see Unix.mkfifo).

> Does anybody know a way to use named pipe of Windows in Ocaml ?

The library you have found is the usual way - you may also like to investigate https://github.com/ocamllabs/ocaml-ctypes which, I believe has good Windows support these days (it's on my list of things to investigate and replace my own Windows C bindings...).

> Thank you in advance for your answer !
>
> Ps : Sorry if it's the wrong mailing list to ask, it's the first time I use one.

This was indeed the correct list, and a good question! Hope the answers help...


--dra