[hylafax-devel] Re: Supporting Digital Modems in HylaFAX.

[Nico Kadel-Garcia <raoul@cirl.meei.harvard.edu>]

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On Tue, 1 Feb 2000, Marcio Saito wrote:

> Hello.
> 
> This is Marcio Saito, I work for Cyclades Corporation (manufacturer of
> serial boards, WAN adapters, remote access servers and routers).
> 
> HylaFAX is new to me. I'm writing to know what is needed for us to
> support Hylafax with digital modems inside a RAS box (not analog
> modems connected to the serial ports of the Unix system).

Whoof! We *like* you! And it's a very good question. Let's see:

HylaFAX runs on UNIX: the RAS box therefore must be an honest-to-ghu
UNIX box, with ghostscript, libtiff, and some other packages
installed.  I suspect you don't want to go there, although if it's
actually Linux or another UNIX at its core it may be feasible.

> One of the products we manufacture is a stand-alone, integrated
> digital RAS box (called Cyclades-PR4000). It connects to a Ethernet
> LAN in one side and to a dialup T1 or E1 trunk in the other side. It
> incorporates a router, a PPP server and the digital modems in one box.
> ISPs use it to provide remote access. For reference, this box is
> functionally equivalent to products such the Lucent Portmaster 3 and
> Ascend MAX 4000/6000.

Not familiar with them myself: I assume that the the PPP service is
pretty much hardwired into the "operating system" of the box, and that
the "operating system" itself is pretty much hard-coded into custom
hardware a bare notch above microcode simply for speed purposes. If
I'm wrong, you're in much better shape.

> The modems inside this box do have support for Fax, but today we don't
> provide any interface to allow an application running in a Unix System
> to access them.

Hmm. How do the users currently get these faxes? If they are
transmitted as tiffg3, the file format for electronic fax
transmissions used by most products and by HylaFAX, it should be
possibly to simply dump them into a file system somewhere and make
that web accessible.  This would be a *USEFUL* project: I think that
most of us have been custom-configuring Linux boxes for modest use
dialup pools and avoiding the scaling issues you will doubtless run
into.

> I understand that one solution would be to provide Unix drivers that
> establish some type of TCP connection with my box and emulate a Unix
> TTY interface for the application. HylaFAX would think the fax-modem
> is local and everything would work.

And this has been done previously: remote terminal servers with modems
hanging off of them have been reported, although I've never been
involved in it myself.

> I don't like that solution (because it depends on proprietary
> interfaces and requires the maintenance of separate drivers for each
> supported operating system).

And I can see why.

Hmm. Outgoing faxes can be sent to a modest, separate, dedicated box,
and the fax requests could be sent (in theory) to your RAS box with a
modest HylaFAX->RAS interface: there are already print spool setups that
do something similar, such as WHFC.

Incoming calls are *already* handled by your system to do PPP and fax
reception: the issue would then be how to transmit the faxes to the
correct destinations. That is a non-trivial problem, usually handled
by sending them to a human who figures out where the heck they go
or leaving them in a fax spool for people to view.

> I was wondering whether or not someone has defined a standard
> interface (probably TCP-socket based) for applications like HylaFAX to
> access modems inside a RAS over the network. If so, I would like to
> know what it is so that we can provide the same interface in my boxes.

I think you're talking about accessing "tty"'s remotely: this is an
*old* issue, dealt with by such varied systems as PPP, kermit, and
telnet.  I'm not sure of details: I'd look into the old
terminal-server work a few years ago, in the mailing list archives.

> If such standard interface doesn't exist, I would like to discuss
> whether or not we can define one, so that HylaFAX and other
> applications could access fax-modems over the network without
> depending on TTY emulation. I'd like to know whether or not there is
> interest among HylaFAX users and developers to support faxes operating
> over a T1/E1 digital trunk.

Oooff. Good idea! Why not talk to Paul Vixie and his people over at
www.vix.com, who provide fax services? I bet they'd love you to
death for providing solid capable hardware for this.

			Nico Kadel-Garcia
			Senior Engineer, CIRL 
			Mass. Eye and Ear Infirmary
			raoul@cirl.meei.harvard.edu

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