From:	SMTP%"thh@lilly.com" 21-JUN-1993 10:24:17.25
To:	EVERHART
CC:	
Subj:	Re: Modifying Symbiont on LAT port

X-Newsgroups: comp.os.vms
Subject: Re: Modifying Symbiont on LAT port
Message-Id: <1993Jun18.144636.296@inet.d48.lilly.com>
From: rz85728@mcvax0.d48.lilly.com (Thomas H. Hopson)
Date: 18 Jun 93 14:46:35 EST
Reply-To: thh@lilly.com
Sender: rz85728@mcvax0.nohost.nodomain (Thomas H. Hopson)
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In article <1993Jun18.121027.100@cesi.it>, sacchi@cesi.it writes:
>We have modified the VMS-Symbiont to convert form DEC Multinational
>Character
>Set to HP LaserJet character set.
>This modified Symbiont, MY_SYMBIONT, invokes the standard
>VMS-Symbiont, PRTSMB.

[...]

>On V6000:
>INITIALIZE /QUEUE /ON=lta9999 /PROCESSOR=my_symbiont my_queue
>
>When a job is completed on queue my_queue, the VAX node V6000 doesn't
>disconnect
>from terminal server.

[...]

>We also have copied from VMSSERV@OAK.CC.KCL.AC.UK the modified symbiont
>HPLASER, but it has the same problem.
>
>Is it possible to invoke LATSYM rather then PRTSYM or how does LATSYM
>close
>connection between the VAX and the terminal server?
>Who can help us on solve this problem?

LATSYM issues a LAT I/O request to disconnect from the LAT channel when
it is done with the LAT port.

The sequence normally goes:

    1. Connect to port.  Issue $QIO with function code 
          IO$_TTY_PORT | IO$M_LT_CONNECT.
    2. Send and receive data as needed.
    3. Disconnect from port.  Issue $QIO with function code
          IO$_TTY_PORT | IO$M_LT_CONNECT.

It seems possible for non-LAT-aware software to simply open a channel to
an already-configured LAT device and start writing and have the LAT
software issue a connection request "automatically".  However, no
disconnection request is issued.

Note that having LAT issue the automatic connection request is NOT
supported by DEC.  From section 8.4.4 of the I/O User's Reference:
"You must use these QIO functions to establish a connection to a 
remote device or service from an application program. Digital does 
not support any other methods of connection."

The LAT functions are described in section 8.4 of the same manual.

If you want to write a symbiont to do this, it will be somewhat more
complicated.

I might suggest an alternate setup.  Create *two* queues, a server queue
and a printer queue.  You print jobs to the server queue where a
symbiont such as CTLSMB (used to come with PMDF; don't know if it's
available anymore or not) translates (or creates a process which does
the translation) between the character sets, making the appropriate 
conversions.  It would then submit the converted file to the printer 
queue, which would use LATSYM and would share the LAT port properly.

It would be kind of like DQS, except it's all on the same node and
there's a translation step in-between the original queue and the
destination (printer) queue.


							- Tom

--
Thomas H. Hopson                   thh@lilly.com
Eli Lilly and Company
Lilly Corporate Center
Indianapolis, IN  46285