Could you please move this discussion to the UPDF reflector?
Unless there's something I'm missing, it seems more appropriate there.
From: owner-pwg-announce at pwg.org [mailto:owner-pwg-announce at pwg.org] On
Behalf Of Norbert Schade
Sent: Wednesday, June 09, 2004 12:10 PM
To: pwg-announce at pwg.org
Subject: PWG-ANNOUNCE> how are optional units managed?
In note 1 I already mentioned that UPDF is supposed to be extensible.
That goes for human languages, but for optional units as well.
A base unit is the printer itself without anything attached to it
(except RAM, which is very predictable).
An optional unit is anything, which can be attached to the base unit or
exchanged like optional trays, a duplexer or a finishing unit.
Most other concepts have to know about optional units before the printer
driver is compiled.
That is a stolid architecture, as you never know, which optional units
may come up after the first launching of the driver and device package.
There are a few concepts out there, where you can add an optional unit
to an existing installation and it will get merged to it. The problem is
detaching it again. Imagine a base unit, which can feed Letter and A4,
and an additional tray, which can feed Letter and A5. merge the sizes to
one list and detach the optional unit. Will Letter size be supported
after the removal?
That's what brought us to separate descriptions for optional units. The
idea is to keep the description separate. So it can be detached without
An optional unit can be described based on the same set of schemas as
the base unit. Just the configuration instance is different (the
configuration of the base unit can refer to more modules).
That allows it to mirror the real world as much as possible: you connect
a real optional unit to a real device --> you add a configuration piece
of the logical optional unit to the logical base unit.
So the main keyword here is Extensibility.
Oasis Semiconductor, Inc.
201 Jones Road
Waltham, MA 02451
email: norbert.schade at oasissemi.com
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