Unix and NT communicating?

Torbjorn Tornkvist <>
Mon Jan 11 04:53:43 CET 1999

> I'm probably misreading something. The question is, can Erlang systems
> running on Unix and Win32 communicate? For example, I'm considering
> connecting FreeBSD and Windows 95 systems running erlang.

Ok, there is a little confusion here what we mean when we
talk about communicating between Unix and Windows using Erlang.


Using the Erlang built-in support to communicate between two
or more Erlang nodes (which may be running on different platforms
such as Unix, Windows, etc...), means that we can, from one Erlang
node, spawn a new Erlang process on another Erlang node, send messages
to an other Erlang node, setup links to other Erlang nodes etc...

This mechanism uses the built-in Erlang distribution protocol (which
runs on top of TCP). As it seems *today*, there are inconsistent versions
of the distribution protocol for the Unix and Window port of Erlang.
This makes it not possible to communicate between such Erlang nodes.

This is probably a very easy fix, which (again probably) will be
provided real soon now... (?)


The other way to communicate between different Erlang nodes is
to use the Socket support. See the Erlang man pages for the Erlang
modules gen_tcp and gen_udp for how to setup TCP/UDP connections
to other Erlang nodes (or other TCP/UDP software). 


> Second question: what's the best way to do device control from Erlang?
> Suppose I wanted to talk to some PC telephony devices, e.g. Dialogic
> cards? 

I know that this has been done using Dialogics card, so someone 
will probably come with a more elaborated answer. 

Basically, you write a C program which you start from Erlang with 
the open_port/2 BIF. The C program relays the data sent between 
your device and your Erlang node. This C program can either be 
run as a stand-alone program (e.g in a separate Unix process) 
or as an Erlang linked in driver. (My advice is to first develop 
and test it as a stand-alone program)

This Erlang/C interface can be written by hand or be generated
(more or less) automatically using the IC or the IG application.
See the documentation. I have myself only used IG (the Interface 
Generator) and can give you more feedback on how to use it if needed.

Some old (but nice ;-) IG documentation can be found at:



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