From:	CSBVAX::MRGATE!info-vax-request@kl.sri.com@SMTP  5-MAY-1988 03:49
To:	ARISIA::EVERHART
Subj:	Re: Trapping broadcast messages.


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Date: 30 Apr 88 06:07:51 GMT
From: bsu-cs!cfchiesa@iuvax.cs.indiana.edu  (Christopher Chiesa)
Organization: CS Dept, Ball St U, Muncie, Indiana
Subject: Re: Trapping broadcast messages.
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I tried to e-mail this response, but it bounced.  So be it...

> I'm using smg$set_broadcast_trapping and smg$get_broadcast_message to trap
> and redirect broadcast messages.  Two questions about this:
> 
> (1) Is there a way of doing this without involving SMG?  (I'm not using SMG
> otherwise.)
> 
> (2) How you I determine the class of the broadcast message (OPER, SHUTDOWN,
> MAIL, GENERAL, etc.)?  I want to pass this information along too.
>

You can trap broadcast messages, and select/deselect classes of them, by 
passing the appropriate parameters to the $QIO system service.  I've been 
writing a program lately, part of which does precisely this.  I'll hold off
posting the source (MACRO assembler; SO THERE, Michael [sorry; inside comment
from the LAST time I posted MACRO code]) until/unless there's a request for
it. 

Basically, you have to do the following:

      *  Create a mailbox (using $CREMBX system service)

      *  Assign a channel to the terminal, with associated mailbox (the 
          one created above) (using $ASSIGN system service).

      *  Set the BRDCSTMBX terminal-mode characteristic ON, and the 
          BROADCAST terminal-mode characteristic OFF (using $QIO system
          service).

      *  Optionally, select the broadcast-message classes you wish the 
          terminal to receive, using $QIO .

   -- after doing all this, any broadcast messages that would normally appear
      on the terminal screen, will be directed to the mailbox instead.  What
      you do with them once this is set up, is your business.  Options include
      reading the mailbox whenever YOU are ready to look at the broadcasts,
      and setting a "write-attention AST" on the mailbox so that a routine you
      specify can be executed IMMEDIATELY when data is written to the mailbox.

   -- and don't forget to "clean up" all this jazz when your program executes;
      that means saving the original terminal characteristics for later resto-
      ration, for one thing...  Terminal characteristics will NOT be automat-
      ically restored by VMS exit handlers when your image terminates. 
-- 
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cfchiesa@bsu-cs.UUCP