Conference bulova::decw_jan-89_to_nov-90

2629.0. "Passing data between two processes" by PEACHS::GILBERT (...You say why, I say I dont know) Wed Apr 18 1990 15:37

I am trying to set up two programs to communicate with each other.
Program 1 is a non-window program which wants to send data asynchonously
to Program 2, an xlib program.  I am thinking of implementing it in the 
following way:

Set up a mailbox between the two programs and set an attention ast on
the mailbox in Program 2.  The AST routine of program 2 simply
reenables the ast and does an xsendevent.  The xnextevent in Program 2
should see this event and control can then be passed to a routine to 
process this data.

Is this a good way to do it?  The worry is that xlib is not reentrent
enough to call xsendevent while it is spinning in xnextevent.  If this is the
"Right" way to do this, is there any particular event that would be better to
use than any other?  Is there a better way? 

Any help would be greatly appreciated.

Thanks,
Jeff

I've done exactly what you outline in .0 and it works.  Aside from a few bugs
that are irrelevant to this case, Xlib is reentrant.  However, avoid any
Dwt or Xt calls.  The Toolkit is not reentrant at all.

--PSW

    
    There was a bug in Xlib prior to VMS version 5.4, wherein AST routines
    which read events or replys would inhibit the non-AST thread from
    returning from Xlib.  To be safe, use VMS 5.4 when you implement your
    program.
    
    Sam