From:	SMTP%"RELAY-INFO-VAX@CRVAX.SRI.COM" 20-JUL-1994 15:42:51.20
To:	EVERHART
CC:	
Subj:	Re: LAT application services and dedicated ports problem

From: flowers@cc.memphis.edu (Harry Flowers)
X-Newsgroups: comp.os.vms
Subject: Re: LAT application services and dedicated ports problem
Message-ID: <1994Jul20.092100.21597@msuvx2.memphis.edu>
Date: 20 Jul 94 09:21:00 -0500
Organization: The University of Memphis
Lines: 28
To: Info-VAX@CRVAX.SRI.COM
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In article <1994Jul19.185512.21581@msuvx2.memphis.edu>, I wrote:
> I'm using application services with dedicated LAT ports.  If you don't know
> what these are, you can probably skip the rest of the post. ;-)  Okay, if
> you haven't skipped, it's where you set up ports for a specific service,
> then have a program that allocates the port, opens a channel, and queues a
> read request to let it know when someone has connected.  When it's done, it
> closes the channel, deallocates the port, and starts all over again.  It's
> nifty, but there's less than a page of documentation on how it all operates!
> (It's in the I/O User's Reference Manual under the LAT part of the terminal
> driver chapter.)  The devices aren't well behaved until someone connects to
> them (i.e., SET TERMINAL will give an error unless someone's connected at
> the time).
> 
> The problem I have is that an I/O is required to let the program know that
> someone has connected to that port, and, if they don't realize that, they
> just sit there and finally try hitting a return.

Mark Berryman wrote me with the answer: use IO$_TTY_PORT!IO$M_LT_CONNECT
instead of IO$_READVBLK, and the QIO will complete when someone connects
to the port.  It works great.  I finally found it in the manual, but not
near the section describing how to set all this up.  Anyway, thanks to
Mark for his answer; now I know someone else out there is actually using
this obscure feature of LAT. ;-)  Oh, and the SET TERMINAL problem is with
temporary characteristics since the port isn't in use.  /PERMANENT would
work (assuming you use privs).
--
Harry Flowers  Internet:FLOWERS@CC.MEMPHIS.EDU or FLOWERS@NARNIA.MEMPHIS.EDU
The University of Memphis, 112 Administration Bldg., Memphis, TN 38152 (USA)