From: schristensen@daimi.aau.dk (Soren Christensen)
To: designCPN@daimi.aau.dk
Date: Mon, 22 Jul 1996 10:11:17 +0200
Subject: Re: Possibility to communicate with a running Unix-process?

The example of communication to a Tcl/Tk script added by Kjeld is definitely
more convincing than my file handling.

It is a little more demanding than my sub-process, since it needs
information on which X-server to use, and thus you should change the way
the sub_process is started. Replace the contents of the global declaration
node with the following:

  color E = with e;

  globref to_prc = IO.std_out;
  globref from_prc = std_in;

  (* change path to fit your filesystem *)
  fun start_process ()
     = let
        val (x,y) = execute_in_env("<specify full path>/sub_process.tcl",[],
            ["DISPLAY=<specify display host>:0.0"]);
       in
        to_prc := y;
        from_prc := x
       end;

  fun send (n:int)
     = (IO.output(!to_prc,(makestring n)^"\n");
        IO.flush_out (!to_prc));

  exception Comm_Err;
  fun check_response ()
     = case input (!from_prc,2)
         of "1\n" => ()
          | _ => raise Comm_Err;

Remember to specify full path and display host in the source code above.

This should take care of Kjeld's problem with the cpnmld daemon...

Regards,
        Soren


>   Additionally to Soren's example, I've included an example where the
>   external executable communicated with is a Tcl/Tk script. In the global
>   declaration node, change the execute file path to point to the Tcl/Tk
>   script sub_process.tcl.
>
>   (If you do not see any graphical feedback when simulating the model,
>   please start manually a cpnmld daemon with a new port number. I do
>   not know why this is necessary, but at least it works for me.)


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| Soren Christensen, Computer Science Department, Aarhus University |
| Ny Munkegade 116, DK-8000 Aarhus C, DENMARK                       |
| email: schristensen@daimi.aau.dk | phone: +45 89 42 32 65         |
| telefax: +45 89 42 32 55         | phone at home: +45 86 93 63 26 |
| WWW URL: <http://www.daimi.aau.dk/~sorenchr>                      |
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