[IPP] Potential errata/update for PWG Raster Format and/or IPP Everywhere specs

[IPP] Potential errata/update for PWG Raster Format and/or IPP Everywhere specs

[IPP] Potential errata/update for PWG Raster Format and/or IPP Everywhere specs

Ira McDonald blueroofmusic at gmail.com
Mon Jun 2 15:45:38 UTC 2014


Hi Mike,

Right - Of course there is no job template attribute for "pdl-override".

There is an "overrides (1setOf collection)" attribute with the specific
job processing instructions to use for forced override.

So my idea is that Validate-Job should tell you *which* of the "overrides"
values will be honored (with "ipp-attribute-fidelity" of 'true').  Why isn't
this useful?

Cheers,
- Ira


Ira McDonald (Musician / Software Architect)
Co-Chair - TCG Trusted Mobility Solutions WG
Chair - Linux Foundation Open Printing WG
Secretary - IEEE-ISTO Printer Working Group
Co-Chair - IEEE-ISTO PWG Internet Printing Protocol WG
IETF Designated Expert - IPP & Printer MIB
Blue Roof Music / High North Inc
http://sites.google.com/site/blueroofmusic
http://sites.google.com/site/highnorthinc
mailto: 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 Mon, Jun 2, 2014 at 11:29 AM, Michael Sweet <msweet at apple.com> wrote:

> Ira,
>
> On Jun 2, 2014, at 11:00 AM, Ira McDonald <blueroofmusic at gmail.com> wrote:
>
> Hi Mike,
>
> What I was trying to "fix" is that "pdl-override" of 'guaranteed' is
> largely
> useless, because the degree of override supported in a given PDL
> interpreter varies.
>
>
> I think you mean 'attempted' here:
>
> pdl-override-supported='guaranteed' means that the IPP Printer will
> guarantee it can override any PDL instructions with the IPP job ticket.  A
> Printer only reports this if it can do so, and I would expect printers to
> be able to do this for JPEG, PDF, and PWG Raster at a minimum.
>
> pdl-override-supported='attempted' means that the IPP Printer will attempt
> to override any PDL instructions with the IPP job ticket.  It could see
> some printers report this for PWG Raster since they might not be able to
> rescale raster data for different media.
>
> pdl-override-supported='not-attempted' means that the IPP Printer will not
> override any PDL instructions with the IPP job ticket. This is by far the
> most commonly reported value for PCL and PostScript printers.
>
> So the IPP Client (sending document data that it did NOT generate but
> that MAY contain job processing instructions) could use 'attempted' to
> learn what is ?safe? to try to override.
>
>
> The Client will never use 'attempted'.  That is a Printer capability that
> the Client can discover via Get-Printer-Attributes. There is no
> "pdl-override" Job Template attribute.
>
> A Client can specify ipp-attribute-fidelity='true' or
> job-mandatory-attributes, and can expect either an outright error at
> submission time (Printer sees a Job Template attribute it cannot override
> and doesn't even try) or an error during processing leading to an aborted
> job (Printer sees something it can't override and reports the error).  And
> for a non-conforming Printer the job might even print without errors.
>
> If this problem isn't worth "fixing", then I suggest that "pdl-override"
> with
> *any* value is not a useful IPP feature - and the Implementor's Guide
> should warn IPP Client developers to avoid using it accordingly.
>
>
> Again, "pdl-override" is not a Job Template attribute.  It doesn't exist.
>
> The guidance here should be to prefer JPEG, PDF, PWG Raster, and other
> well-defined file formats over legacy formats like PCL and PostScript,
> specifically because overrides are better supported and output is more
> consistent.  And in the same place we can offer a warning/note about legacy
> PDLs - they are printer specific and often need the output intent embedded
> in them vs. as IPP Job Template attributes.
>
> We should probably also provide guidance to Printer implementations (and I
> think we already have this) on what value(s) to report for
> "pdl-override-supported" and how to deal with attributes that cannot be
> overridden.
>
>  _________________________________________________________
> Michael Sweet, Senior Printing System Engineer, PWG Chair
>
>
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