Hi Ira,
Understood . but I believe it is more polite to ask permission before
posting to the list emails sent privately.
I simply suggested that, to satisfy the requirements you listed in the
document, it is necessary to be able to understand what the PDL is, and
because there are differences in emulations and versions, it may be
necessary that the reader be aware of the emulation or version. If there is
no way of providing this information, then interpreter either has to deal
with a PDL that is not quite what it says it is, or it has another private
PDL to accommodate. In either case, the underlying objective of the
specification is compromised. Currently, although the string may not be as
machine readable as desired, that information about version and emulation is
available.
I believe that these are valid points to be considered both by printer
manufacturers and those reading the string. It may well be that, rather than
provide incomplete information, it would be better to use the current
approach.
Bill Wagner
From: Ira McDonald [mailto:blueroofmusic at gmail.com]
Sent: Wednesday, January 27, 2010 8:13 PM
To: William Wagner; Ira McDonald
Cc: wims at pwg.org; Jerry Thrasher
Subject: Re: [PDL versions?] PWG last call - Command Set Format - IEEE1284
Device ID -25 Feb 2010
Hi Bill,
[please read the mail headers in this thread]
I already PUT it on the WIMS WG mailing list - because ALL
PWG Last Call comments are supposed to be publicly posted
and archived.
I do not find any basis for document format variants in the
requirements you quoted.
And the basic method (using Printer MIB enum labels) has
been unchanged (and unchallenged) ever since Mike Sweet
originally proposed this standard at the Open Printing Summit
in Montreal in fall 2007 and the PWG SC agreed to look into
it (i.e., it became my long-standing action item).
This interoperable labeling of document format variants (which
is NOT possible in Printer MIB) is a major new requirement.
Allowing document format variant labeling may be possible
with some suffix syntax, but *interoperable* document format
variant labeling is simply impossible.
Vendors don't currently use the same version numbers to
mean the same thing, and it's way out-of-scope for this
specification to solve *that* problem.
Cheers,
- Ira
Ira McDonald (Musician / Software Architect)
Chair - Linux Foundation Open Printing WG
Co-Chair - TCG Hardcopy WG
IETF Designated Expert - IPP & Printer MIB
Blue Roof Music/High North Inc
email: blueroofmusic at gmail.com
winter:
579 Park Place Saline, MI 48176
734-944-0094
summer:
PO Box 221 Grand Marais, MI 49839
906-494-2434
On Wed, Jan 27, 2010 at 5:41 PM, William Wagner <wamwagner at comcast.net>
wrote:
Do either of you object if we put this on the PMP/WIMS mailing list and
include it in the face-to-face discussion?
With respect to Ira's comments, one may argue that design requirements 5-7
. should support automatic device driver installation by client and
server operating systems (see section 3.2).
. should support interoperable advertising of implemented document
formats by network spoolers and network Printers (see sections 3.1 and 3.2).
. should support interoperable discovery of available document
formats by Imaging Clients and Imaging Servers (see sections 3.1 and 3.2).
would suggest a document format method that did distinguish between
variations on a language without the need for creating a slew of
vendor-specific language identifications.
Thanks,
Bill Wagner
From: Ira McDonald [mailto:blueroofmusic at gmail.com]
Sent: Wednesday, January 27, 2010 3:29 PM
To: William Wagner; wims at pwg.org; Ira McDonald
Cc: Jerry Thrasher
Subject: Re: [PDL versions?] PWG last call - Command Set Format - IEEE1284
Device ID -25 Feb 2010
Hi Jerry,
The short answers to your questions are:
(1) Distinguishing Emulation from Genuine was not a
design objective.
(2) Distinguishing PDL versions was also not a design
objective (or plausibly interoperable).
- The use and misuse of the corresponding version
elements in the Printer MIB v1/v2 prtInterpreterTable
is a hopeless mess.
- Nobody was willing to let the editors to address this
when we did Printer MIB v2.
So, inserting version information may work for a given
vendor, but completely breaks interoperability across
different spoolers and OS environments.
We could perhaps introduce a syntax for version
suffixes, but the chances that vendors will correctly
implement it seems very unlikely.
Bearing in mind the machine-readability imperative,
do you have an interoperable version suffix format
to propose?
Or an interoperable Emulation versus Genuine suffix
format?
Cheers,
- Ira (1284 Cmd Set editor)
Ira McDonald (Musician / Software Architect)
Chair - Linux Foundation Open Printing WG
Co-Chair - TCG Hardcopy WG
IETF Designated Expert - IPP & Printer MIB
Blue Roof Music/High North Inc
email: blueroofmusic at gmail.com
winter:
579 Park Place Saline, MI 48176
734-944-0094
summer:
PO Box 221 Grand Marais, MI 49839
906-494-2434
On Wed, Jan 27, 2010 at 11:58 AM, William Wagner <wamwagner at comcast.net>
wrote:
Hi Jerry,
I am sending your questions onto Ira. I think your two points are very good
ones. My take on them:
The spec allows for PrtInterpreterLangFamilyTC, mime-media-type, and Private
type designations. PrtInterpreterLangFamilyTC does not provide for version
and emulation variations; mime-types for all of the variations do not exist,
and would be cumbersome if they were to be all registered; and having
applications understand the difference between private types is unrealistic.
The intent is machine identification of the command language. Just
indicating (by an appropriate means. placing "emulation" after the
designation does not appear consistent with the spec) that a pdl is an
emulation warns the interpreter that there may be differences from the
defined set, but these will likely be different from one emulation to
another. I think the best approach depends on how good the emulation is (as
an emulation, not as a PDL). But, barring having to define and designate
each emulation as a separate PDL, there might be some benefit in somehow
flagging that a PDL might deviate somewhat from the defined language.
Major Version differences are likely more drastic, more likely to be
independently defined and since there should be fewer of them that possible
emulations, more amenable to being listed as separate MIB or MIME types.
That is, there is little advantage in knowing the language is up-version
(other than expecting differences) unless the interpreter knows what the
differences are. To be able to do this, the version and its definitive
reference should be identified in a standard way. The problem then, of
course, is who is going to register these versions.
Thanks for the input.
Bill Wagner
Jerry Thrasher/Lex/Lexmark
01/27/2010 09:07 AM
To
"William Wagner" <wamwagner at comcast.net>
cc
Subject
Re: [Pwg-Announce] PWG last call - Command Set Format - IEEE1284 Device
ID -25 Feb 2010
Bill,
A couple of questions have come up with respect to what's really required to
be done and what
can be done with respect to two particular issues.
1. The percieve requirement for not confusing PDL emulation with "true" PDL
support
Example, Postscript Emulation vs. Adobe PostScript and PCL Emulation vs. HP
PCL support.
2. The need for the ability for versioning of the various PDLs.
PCL 6 is very different from PCL 3 (most low end inkjet printers still
support only PCL 3, the first
PCL to support color).
So here's what I'm talking about from a real string.
Example:
If the current CMD string is:
COMMAND SET:PCL 6 Emulation, PostScript Level 3 Emulation, NPAP, PJL;
Would a compliant string simply be:
COMMAND SET:PCL,PS,PCL 6 Emulation, PostScript Level 3 Emulation, NPAP, PJL;
_____________________________________
LEXMARK
Jerry Thrasher
Senior Engineer, WW Corporate Standards
C14/082-1, 740 New Circle Rd, Lexington Ky 40550
Office: +1 859 825 4056 Fax: +1 859 232 7628
thrasher(at)lexmark(dot)com
--
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