[IPP] WG Last Call of IPP Scan Service specification

[IPP] WG Last Call of IPP Scan Service specification

[IPP] WG Last Call of IPP Scan Service specification

William A Wagner wamwagner at comcast.net
Wed May 21 16:06:09 UTC 2014


I find myself in the unusual position of concurring with (almost) all. 

1.       If attributes expressed in date-time are required, then the printer
presumably knows (or can determine) current date time and
"printer-current-time" should be required.

2.       This should be consistent across IPP imaging services

3.       The notion of requiring an attribute but not requiring that the
date-time value be valid was, if I recall correctly, a concession to the
limitations of low-cost printers that seems to have persisted.  I suggest
that this is inappropriate for a networked printer today. 

4.       I agree that making an attribute required cannot be considered an
editorial correction fixable by an errata (even if it was an oversight).

Thanks,

Bill Wagner

 

From: ipp-bounces at pwg.org [mailto:ipp-bounces at pwg.org] On Behalf Of Michael
Sweet
Sent: Wednesday, May 21, 2014 9:45 AM
To: Ira McDonald
Cc: IPP at pwg.org
Subject: Re: [IPP] WG Last Call of IPP Scan Service specification

 

Ira,

 

Given that it changes the conformance requirements, I don't think it can be
done as an errata.  However, we *could* make it RECOMMENDED (much like we
did when we published IPP/2.0 Second Edition for a number of attributes...)

 

But we should definitely add this to the list of future changes for IPP
Everywhere 2.0 / IPP Multifunction.

 

 

On May 21, 2014, at 9:22 AM, Ira McDonald <blueroofmusic at gmail.com> wrote:





Hi Mike and Soma,

Then I maintain that it's an error in IPP Everywhere, FaxOut, and Scan,
that the underlying "printer-current-time" (OPTIONAL in RFC 2911 and

in IPP/2.0 Second Edition) is not moved to REQUIRED.  I consider it
an editorial error (i.e., fixable by an errata) as it's an oversight.

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/blueroofmusic
 <http://sites.google.com/site/highnorthinc>
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 Wed, May 21, 2014 at 8:54 AM, Michael Sweet <msweet at apple.com> wrote:

Soma,

 

This is indeed something that needs to be documented in the implementor's
guide, but in most cases the client just needs to see whether the date/time
(or simply the up time in seconds) is different than last reported, and not
if the change is newer.

 

But given that the printer-xxx-change-date-time attributes are required in
IPP Everywhere, I think we still want them required for IPP Scan.

 

 

On May 20, 2014, at 11:09 PM, Soma Meiyappan <Soma.Meiyappan at conexant.com>
wrote:





Hi Ira,

 

Thank you very much for the summary from the F2F discussions on this topic. 

 

My question on the topic for FaxOut stems from the imaginable ways an IPP
client may have been written to be dependent on
printer-config-change-date-time for caching printer confifuation  and if it
is a value that may be treated as trusted enough for that purpose. I am
aware that 'no-value' is valid for these attributes (incl
printer-current-time); but I am concerned about other valid (but inaccurate)
dateTime values and the implications.

 

If 'printer-config-change-date-time' is used purely for informational
purposes (as a value to display in a report or a web-page and not
necessarily in caching the printer configuration), I'll not be too
concerned. However, could it be used to determine if cached information
about the printer needs to be refreshed? If yes, we may want to add a note
targeted at IPP client writers, in the implementer's guide, that this
information MUST not be used for caching printer capabilities without other
precautions including protection against the possibility of the printer
reported time being inaccurate [RFC 2911 does not place any accuracy
requirements] and printer-current-time (and derived attribute values) going
back to the past for a number of reasons. 

 

Looking forward to hearing the forum's thoughts on the topic.

 

Thanks and Regards,

Somasundaram.

 

 

From: Ira McDonald [mailto:blueroofmusic at gmail.com] 
Sent: Monday, May 19, 2014 11:23 PM
To: Soma Meiyappan; Ira McDonald; Peter Zehler
Cc: IPP at pwg.org
Subject: Re: [IPP] WG Last Call of IPP Scan Service specification

 

Hi Soma,

Thanks for your careful reading of these IPP specs.

We discussed this comment during the Thursday IPP WG session 

at the PWG F2F meeting last week, when looking at IPP Scan with

Pete Zehler.

 

The IPP F2F minutes state that this issue should be resolved on the 
IPP mailing list, but there was unanimous consensus in the meeting:

 

(1) IPP FaxOut - these date-time attributes should remain REQUIRED

(because they satisfy regulatory requirements for a Fax service).


(2) IPP Scan - these date-time attributes should be changed to either

RECOMMENDED (i.e., best practice) or simply OPTIONAL.

Please note that in IPP Everywhere (PWG 5100.14), the attributes

printer-config-change-date-time and printer-state-change-date-time

attributes are REQUIRED in Table 6 for conformance (see notes 2

and 3 below the table).

 

Obviously, the underlying printer-date-time attribute should have

the same conformance level as the change-xxx attributes in IPP 
Everywhere, IPP FaxOut, and IPP Scan.  This appears to me to
be an oversight in these specs.

Please comment further on this thread, to clarify your thoughts.

Cheers,

- Ira (co-chair of IPP WG)




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/blueroofmusic
 <http://sites.google.com/site/highnorthinc>
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 Tue, May 13, 2014 at 10:34 PM, Soma Meiyappan
<Soma.Meiyappan at conexant.com> wrote:

Hi Pete et al,

 

I have a concern about

 

printer-config-change-date-time 

printer-state-change-date-time 

 

These attributes figure in the REQUIRED table in section 4.3. The above
attributes require the scan device to have a notion of wall clock time
(whether it is accurate or not to the global wall clock time). To increase
the chances of making use of that effectively & correctly, all clients would
be required to use this somehow in reference to printer-current-time and not
to the wall-clock time that the client might know through other sources.
That makes me wonder if it is sufficient to have printer-state-change-time
and printer-config-change-time as required and make xxxx-date-time as
optional.

 

I have a similar question on FaxOut; but at least on FaxOut, the devices are
expected to have a notion of wall-clock time although the point about how
clients should use that information with reference to printer-current-time
still seems applicable.

 

Regards,

Somasundaram.

 

From: ipp-bounces at pwg.org [mailto:ipp-bounces at pwg.org] On Behalf Of Zehler,
Peter
Sent: Friday, May 09, 2014 10:35 PM
To: IPP at pwg.org
Subject: [IPP] WG Last Call of IPP Scan Service specification

 

All,

This message initiates the IPP Working Group last call of the IPP Scan
Service specification updated per prototype experience and subsequent
discussions.  

 

ftp://ftp.pwg.org/pub/pwg/ipp/wd/wd-ippscan10-20140509.pdf    

http://ftp.pwg.org/pub/pwg/ipp/wd/wd-ippscan10-20140509.pdf   

 

Please send all feedback to the IPP mailing list (reply-all works fine for
this) and it will be collected and processed as quickly as possible. 

Our intent is to move IPP Scan Service to PWG Formal Vote before the August
2014 F2F.

 

Peter Zehler

Xerox Research Center Webster
Email: Peter.Zehler at Xerox.com
Voice: (585) 265-8755 <tel:%28585%29%20265-8755> 
FAX: (585) 265-7441 <tel:%28585%29%20265-7441> 
US Mail: Peter Zehler
Xerox Corp.
800 Phillips Rd.
M/S 128-25E
Webster NY, 14580-9701 

 

 


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_________________________________________________________
Michael Sweet, Senior Printing System Engineer, PWG Chair

 

 

 

_________________________________________________________
Michael Sweet, Senior Printing System Engineer, PWG Chair

 

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