Re: EPX prototyping issue / question: does Printer need to support "copies" in order to support "proof-copies"?

Michael Sweet via ipp <[email protected]> Thu, 12 Oct 2023 08:52:08 -0400

Newsgroups	gmane.ietf.ipp
Message-ID	<[email protected]>

Smith,

> On Oct 11, 2023, at 10:52 PM, Kennedy, Smith (Wireless & IPP Standards) via ipp <[email protected]> wrote:
> 
> Signed PGP part
> Hi there,
> 
> I've successfully prototyped Job Storage, Job Release and Job Policy, and I had successfully prototyped Job Proof and Suspend, but the latter was tenuous and is now broken again. The difficulty is that I need to use a document format that calls my driver's "driver_data->rendpage_cb" callback so that I can count pages. The driver claims that its document format is PWG Raster, and PAPPL treats PWG Raster as a streaming-only document format. (I could be just confused about some of this and doing it wrong...I don't want to write document parsing code that counts pages for PDF, etc.)

In order for entry-level Printers to support "driverless printing" and IPP, streaming raster formats are largely pre-processed, including the production of copies by the Client.  The "job-pages-per-set" attribute was added in order to support finishing and other copy/set-based processing of these streaming raster formats...

So in the context of streaming raster formats and "proof-copies", I think it would make sense to also require support for "job-pages-per-set".  But I think that Printers that implement EPX will also implement higher-level formats such as PDF, making support for/use of proof copies + streaming raster to be a very small edge case.

> But that got me wondering about the EPX definition of "proof-copies" in section 6.2.2. It says that a Client that supplies "proof-copies" must ALSO supply "copies", which means that Job Proof and Suspend cannot be implemented on streaming (non-spooling) printers that don't support "copies", only "job-pages-per-set", and the document submitted has the copies resent by the client (e.g. for 3 collated copies of a 5 page document, the client sends 15 pages - the 5 page document 3 times). Is that a limitation we still believe the specification ought to impose?
> 
> Perhaps we can discuss this tomorrow at the IPP WG meeting.

We should definitely have the discussion.

________________________
Michael Sweet

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