NetNews Usenet Archive 1992 #20/NN_1992_20.iso/spool/comp/os/os2/misc/30050

Internet Message Format | 1992-09-14 | 3.4 KB

Path: sparky!uunet!dtix!darwin.sura.net!gatech!news.ans.net!ans.net!db3l
From: [e-mail] (David Bolen)
Newsgroups: comp.os.os2.misc
Subject: Re: Application to open serial connection and leave it open
Message-ID: <[e-mail]>
Date: 14 Sep 92 13:43:06 GMT
References: <ant.716450715@brolga>
Sender: [e-mail] (News Administrator)
Organization: Advanced Network & Services, Inc. - Elmsford, NY
Lines: 65
In-Reply-To: [e-mail]'s message of Mon, 14 Sep 1992 06: 05:15 GMT

In article <ant.716450715@brolga> [e-mail] (Anthony Murdoch) writes:

>I was wondering if anyone had a method of making a modem connection to a
>service and then leave it open after it exited (ie not dropping DTR).  My
>reason for asking is to allow IBM's TCP/IP's SLIP to work with the SLIP
>Terminal Server at my site.
>
>I need to be able to make the connection, log into the service, disconnect
>from the comms application and then run the SLIP command to make the slip
>connection.  Unfortunately IBM's TCP/IP doesn't have any provision for
>this (at least not that I can see).

You are correct - IBM's setup doesn't provide for this right now.

Ideally, the program responsible for dialing up and establishing the SLIP
link could pause the SLIP driver while it accessed the COM port (ala SLIPCALL),
but the current SLIP driver uses a semaphore mechanism that isn't too
reliable (it's gotten worse in recent releases), so it's often safer to just
establish the connection without involving the SLIP driver at all.

However, the SLIP driver opens the COM port in shared mode, so you can have
another program running that is keeping the COM open and it won't affect SLIP,
or you can start SLIP later in the connection process than you might think.

For example, you could set up three processes:

* A COM Hold process - does nothing other than do a shared open on the
  appropriate COM port, and sit around until you exit it.  As long as this
  is running, OS/2 won't "hang up" the port.
* A simple terminal program that also opens the COM port in shared mode.
  This allows you to talk to the modem - dial - log in, etc..
* The SLIP driver.

And you would do the following:

1. Run COMHOLD - leave running.
2. Start terminal program - log in as appropriate and establish SLIP setup.
3. Exit terminal program.
4. Start SLIP driver.
5. Exit COMHOLD

It's somewhat manual, but it definitely works, and really isn't that bad.

The actual processes are very simple - if you can compile your own stuff,
the only real important thing is that whenever the COM port is opened, it
should be in shareable mode, as in:

    DosOpen("com1",&com_handle,&action,0,0,FILE_OPEN,
                OPEN_ACCESS_READWRITE | OPEN_SHARE_DENYNONE,NULL);


I think I've got stuff like this lying around somewhere (although the terminal
part is all manual - no automatic login scripts or anything) from when I
needed it, so if you don't have facilities to compile anything, drop me a
note.  I need to rebuild it to remove some internal numbers, but that's no big
deal.

--
-- David
--
/-----------------------------------------------------------------------\
 \              David Bolen             \  Internet: [e-mail]      /
  |   Advanced Network & Services, Inc.   \   Phone: [phone]   |
 / 100 Clearbrook Road, Elmsford, NY 10523  \   Fax: [phone]    \
\-----------------------------------------------------------------------/