I've posted a 9-page talking paper with diagrams that a number of us at
Xerox collaborated on about the Set2/3 Printer vs. Device operation/object
semantics:
ftp://ftp.pwg.org/pub/pwg/ipp/new_OPS/ipp-printer-and-device-semantics-99120
3.doc
ftp://ftp.pwg.org/pub/pwg/ipp/new_OPS/ipp-printer-and-device-semantics-99120
3.pdf
We'd like to discuss it at the Wednesday's IPP telecon, 12/8/99, 1-3 EST
(10-12 PST).
At the Raleigh IPP meeting when reviewing the Set2 and Set3 operations, we
agreed that the recommended way to model fan-out was to use subordinate
Printer objects so that real status of each fan-out output device would be
represented as an IPP Printer object. We also agreed that there should be
separate Device operations that affected what IPP/1.1 calls the
"output-device" (lump of metal) and that the Printer operations should be to
affect the IPP Printer object only. Subsequently, we had a good IPP
telecon on Wednesday, November 17, 1999 on trying to disambiguate the
semantics of the IPP Printer operations on the one hand that affect the
software abstraction in each of its possible configurations and (new) Device
operations that affect what [ipp-mod] calls the "output device" ("lump of
metal") on the other hand.
This talking paper is an attempt to write down the semantics of the Printer
versus the Device operations. We suggest that there is not a need for a
Device object, only Device operations. Not having a Device object
significantly simplifies the semantics: there are no Device attributes and
no Get-Device-Attributes and Set-Device-Attributes operations. If some
Printer MIB attributes are needed, they can be added to the Printer object,
but this should be done on a case by case basis with good justification.
We've also simplified the operation semantics so that they can be stated
consistently for any of the configurations that are shown in the diagrams.
This is a talking paper, not a complete spec. If we get agreement on this
talking paper, we can produce the detailed spec for Set2 and Set3 very
quickly. It makes very few changes to the Set2 spec (mostly clarifies some
of the operation semantics) that was posted November 17. The diagrams of
fan-out and fan-in remain unchanged:
ftp://ftp.pwg.org/pub/pwg/ipp/new_OPS/ipp-ops-set2-991116.docftp://ftp.pwg.org/pub/pwg/ipp/new_OPS/ipp-ops-set2-991116.pdfftp://ftp.pwg.org/pub/pwg/ipp/new_OPS/ipp-ops-set2-991116-rev.docftp://ftp.pwg.org/pub/pwg/ipp/new_OPS/ipp-ops-set2-991116-rev.pdf
Please send any comments to the mailing list and join the telecon. Help us
decide what to review at the L.A. meeting the following week.
Thanks,
Tom