From: hoffman@xdelta.zko.dec.nospam
Sent: Thursday, June 21, 2001 3:02 PM
To: Info-VAX@Mvb.Saic.Com
Subject: Re: connect to XServer over decnet

In article <Oozvf8elmJpy-pn2-cnC7s0mU0oIP@Tom2>, Thomas.Hahnemann@nospam_s-t.de (Thomas Hahnemann) writes:
:Is there a way to do 
:
:set display /create/trans=decnet/node=mynode/screen=1
:
:without DCL, means to create a working display logical from a C-programm?

  WARNING: the WS-class device $qio interface is undocumented, unsupported, 
  and subject to change without notice.

  You can explicitly specify the target display name directly on the 
  XtOpenDisplay call, IIRC.  Strings like 0:0.1 (for IP) or 0::0.1 
  (for DECnet) should work, again, IIRC.  By default, the DECW$DISPLAY 
  logical is is used to find the WS-class device, and from there the 
  target host, protocol, display, and screen.  Check the XtOpenDisplay 
  documentation in the DECwindows documentation set and in the X Windows 
  documentation.  Also poke around in some of the DECwindows and X Windows
  example programs that are around.

  The SET DISPLAY and SHOW DISPLAY commands store and retrieve the 
  information on the target using a WS-class pseudo-device, and
  specifically the contents of the WS-class unit control block (UCB).  
  While the WS-class device $qio interface is undocumented and 
  unsupported, there exists an example of a SHOW DISPLAY tool 
  available on the OpenVMS Freeware.

  The Freeware example program uses SENSEMODE to read the values, and
  you can use SETMODE to write the values into the WS-class device. 
  (Target an existing WS-class device, or $assign to the WSA0: template
  to get a new device, then update the device UCB contents).  For example:

        ...
        #include <iodef.h>
        #include <efndef.h>
        #include <ssdef.h>
        #include <stsdef.h>
        ...

        ItemCode = DECW$C_WS_DSP_NODE;
        RetStat = sys$qiow ( EFN$C_ENF, IOChan, IO$_SETMODE|IO$M_WS_DISPLAY,
                   0, 0, 0,
                   DisplayNode.dsc$a_pointer,
                   DisplayNode.dsc$w_length,
                   ItemCode, 0, 0, 0);
        if (!$VMS_STATUS_SUCCESS( RetStat ))
          lib$signal( YOUR_APPLICATION_SPECIFIC_ERROR_CODE );

  See the Freeware example for the remainder of the "interesting stuff", 
  such as the DECW$C_WS_DSP* symbol definitions, etc.

  WARNING: the WS-class device $qio interface is undocumented, unsupported, 
  and subject to change without notice.

 ---------------------------- #include <rtfaq.h> -----------------------------
      For additional, please see the OpenVMS FAQ -- www.openvms.compaq.com    
 --------------------------- pure personal opinion ---------------------------
   Hoff (Stephen) Hoffman   OpenVMS Engineering   hoffman#xdelta.zko.dec.com