Hi,
at long last I have now pulled myself together to edit up the minutes from
Munich. My thanks to Randy and Scott who took the actual notes during the
meetings. I have gone over their notes and edited out the things that were
not controversial, to mainly leave in the things that need further action.
Hope I did not leave out anything of importance. Here is the text:
---
IETF-39 - Minutes from the IPP WG sessions
on Monday August 11 and Wednesday August 13, 1997
==================================================================
Chairs: Carl-Uno Manros and Steve Zilles
The Monday session meeting was attended by about 35 experts and the
Wednesday session by about 25. A total of 48 experts signed up on the
attendance sheet.
All of the WGs Internet-Drafts were open to review and comments.
Session on Monday, August 11 (minutes taken by Randy Turner)
============================
Carl-Uno Manros opened the meeting and reviewed the agenda.
The I-D: <draft-ietf-ipp-req-00.txt> Requirements for an Internet
Printing Protocol
was briefly introduced. This document will need some updating
to align with more recent documents, otherwise no comments.
Steve Zilles then briefly provided a quick overview of IPP,
specifically the object concept.
The I-D: <draft-ietf-ipp-rat-01.txt> Rationale for the Structure of
the Model and Protocol for the Internet Printing Protocol
was briefly discussed, limited to the model aspects, without any
substantial comments.
The I-D: <draft-ietf-ipp-model-04.txt> Internet Printing Protocol/1.0:
Model and Semantics
was introduced by Scott Isaacson. This is the key document for
IPP and still contained a number of open issues. Scott had prepared
proposed resolutions to all the issues flagged, based on WG input
since the draft was published. Most of the proposed resolutions
were uncontroversial, but the following raised some discussion:
1. Compression of IPP messages
This issue is OPEN. The WG is looking at other standards and
existing enumerations for compression algorithms.
2. Alignment with Job Monitoring MIB
job-k-octets, job-impressions, and job-media-objects will be
aligned semantically with the Job Monitoring MIB.
One note about the Job Monitoring MIB. Keith Moore, Area Director
for Applications, noted that there is no formal IETF working group
chartered for the Job Monitoring MIB effort. Further, there may be
problems with IPP documents achieving "proposed" status if IPP
documents reference such other documents. He reiterated that the
Printer Working Group had submitted an extension to the Printer MIB
working group's charter to include the Job MIB, but that the request
had not been processed by the IESG, so there may be a problem here.
3. Human Language and Character Set
IPP mandates UTF-8 for application/ipp messages. HTTP Accept-Headers
will be used for human-language attributes. Questions from the
audience asked about whether the WG had considered the use of
an updated Unicode spec. UCS-4 which is currently being proposed.
Scott Isaacson implied that the WG is open to suggestions as to
what standard should be applied here. The basic theme echoed by
Keith Moore was to try and follow Harald Alvestrand's document, and
if better methods are suggested, the IESG will keep an open mind.
4. Job-URI attribute
"A lively discussion ensued". Basically, it was agreed that
this issue is still OPEN and will be discussed on the mailing
list.
5. Use of "Conditionally Mandatory" in IPP documents.
The I-D will be re-edited to focus on what must be implemented
in order to realize certain specific functional components.
Keith Moore reflected on current IETF documents for keywords
such as MUST, SHOULD, MAY, etc. and that the WG should try and
follow the IETF guidelines and best current practice with
regards to such conformance/compliance vocabulary.
6. Use of MIME types for "document-format"
Currently, the model document specifies the use of Printer MIB
enumerations for specification of document-format. In addition,
at a recent PWG meeting, it was agreed that enumerations for
PDF and HTML ought to be added to this list.
Upon hearing the proposed alignment with the Printer MIB for
these values, "a lively discussion ensued".
It was the opinion of Larry Masinter (chair of HTTP WG), Keith
Moore, and most of the IETF audience that alignment with the
Printer MIB was a mistake, and that we should focus on sticking
with MIME-type specifications.
Further, Keith Moore went on to say that the current draft of
the Printer MIB was "broken", and that he is seriously
considering delaying advancement of the Printer MIB draft until
this (and possibly other) issues are addressed. Keith did not
go into any detailed analysis of why the MIB was broken, but
seemed to suggest that there were more than one reason why it's
broken. He went on to say that its possible that (ironically)
the IESG might suggest to the working group that the Printer
MIB should align itself with the MIME-types and change the way
that interpreters are enumerated in the MIB. He suggested that
the group should consider strings, and not enumerations, to
specify these types (i.e., MIME types). Keith was pretty adamant
on this issue and would have continued discussion, but Steve Z.
and Scott suggested that discussion on the Printer MIB was
not appropriate at an IPP WG meeting.
7. Server Timeout
The printer will abort a job after some server-configured
inactivity timeout. If some documents had already been printed,
the rest of the job is canceled. Larry Masinter questioned
why IPP operations could not be "re-tried" if a failure occurred.
Steve Zilles responded that there might be idempotency problems
with operation retries. More discussion on the mailing list
should be done.
8. Version Numbers
Given the number of HTTP WG members in the room, "a lively
discussion" on capability negotiation and version numbers
ensued. It is very likely that some combination of versioning,
and capability negotiation will be required before gaining
IESG acceptance.
9. Color
Will remain a boolean, "color-supported'. Leave it to the PDL
to handle other color model and capabilities requirements.
Some questions by the audience questioned the usefulness of a
"boolean" to specify color capabilities. Keith Moore said that
he would like to see the specification of color capabilities
more fleshed out than just "yes, this device supports color".
Larry Masinter also suggested that in order to curb the
displeasure with such a "boolean" specification of color, that
maybe the WG should remove this and just do a complete color
capabilities model in a future version of IPP. He suggested that
either IPP should do color (the right way), or not at all.
After a brief rationale statement by Scott Isaacson and Steve
Zilles for the boolean color-supported, both Larry and Keith
seemed to understand why, but still were not crazy about the
inclusion of color, without the WG "doing it right".
10. Date and Time
"time-since-xxxx" attributes will be in "seconds" (and OPTIONAL).
A MANDATORY "printer-up-time" will be added to the spec. and
will essentially reflect the MIB-II "sysUpTime" object. Larry
Masinter questioned why a printer "end-user" would care about
how long the printer had been "up", since IPP 1.0 is basically
targeted for end-users. He further questioned why the value
was mandatory. The WG implied that since MIB-II sysUpTime was
mandatory, that no undue burden should be placed on IPP
implementations to support it.
11. Formatting Attributes
The WG will work on a proposal for "page-range" and
"page-orientation" attributes.
12. Order of Jobs returned by "Get-Jobs"
OPEN.
13. Event Notification
The WG has an action item to specify event notifications. They
should be machine-readable.
14. media-ready vs. media-supported
OPEN. Some implementation require this distinction. Especially
server-based implementations of IPP. It was suggested that
media-supported be dropped and only support for media-ready
should be supported, since this would apply to all IPP
configurations.
The I-D: <draft-ietf-ipp-dir-schema-01.txt> Internet Printing Protocol/1.0:
Directory Schema
was introduced by Scott Isaacson.
More work needs to be done to bring the current directory schema
documents up to date with the current Model document. One of
the members of the Service Location Protocol WG mentioned that
they already have started working on a schema for Printing Class
applications within their WG, and that input from the IPP WG
is "very welcome" at this stage. Scott Isaacson stated that
such cooperation should definitely take place.
Session on Wednesday, August 13 (minutes taken by Scott Isaacson)
===============================
Carl-Uno Manros opened the meeting and presented the agenda.
The I-D: <draft-ietf-ipp-rat-01.txt> Rationale for the Structure of
the Model and Protocol for the Internet Printing Protocol
was introduced by Steve Zilles and then briefly discussed, limited
to the protocol aspects, without any substantial comments.
The I-D: <draft-ietf-ipp-sec-01.txt> Internet Printing Protocol/1.0:
Security
was introduced by Carl-Uno Manros. The following comments and
discussion followed:
1. Scope of security in IPP
What is in and what is out of IPP? How much can we rely on getting
from the numerous IETF security projects and what do we have to do
ourselves? Should not the HTTP group be responsible for security
needed for HTTP? How is the use of TLS with HTTP specified?
HTTP seem to ignore further standardization of Basic Authentication
and are only progressing Digest Authentication.
2. Status of IETF security standards
There is an interest from IPP to use TLS for secure transmission,
but the TLS standard is not yet finished. Can SSL be used instead?
3. Secure and insecure communication with the same IPP Printer
We should allow for the protocol to have some kind of negotiation
mechanism. One suggestion was to always use TLS, allowing the client
to be configured to run with TLS NULL, NULL, NULL.
It was also stated that the content of the current document will be
divided up between the IPP Model & Semantics and Protocol Specification
document in the next round of editing.
The I-D: <draft-ietf-ipp-protocol-01.txt> Internet Printing Protocol/1.0:
Protocol Specification
was introduced by Bob Herriot. The following comments and
discussion followed:
1. Does IPP need to worry about the fact that some server implementations
do not pass HTTP headers to the back end processes (CGI)?
No, this is an implementation problem.
2. Accept headers
Accept-charset is irrelevant
Accept-language is relevant
Accept-encoding probably (might be)
3. We need to make sure that the IPP mapping works with generic HTTP
clients, HTTP origin servers, and HTTP proxy servers
4. Why POST over new method PRINT?
PRO POST
It is there
It works
It really doesn't matter
CON POST
Harder for proxy server to differentiate
Better performance with native method
POST was intended to be a "big hole"
WEBDAV uses XML and new methods
RESOLUTION: Use POST for all of the reasons identified and move on.
5. Why not use some other transport, such as SMTP?
IPP has been designed not to prevent this, however no interest in the
WG to make such other mappings.
Additional mappings could show a mapping of multiple operations in one
MIME component, or could use Internet Fax extensions.
6. Content negotiation should be more symmetrical (client telling server,
server telling client)
The I-D: <draft-ietf-ipp-lpd-ipp-map-01.txt> Mapping between LPD and IPP
Protocols
was introduced by Bob Herriot. The following points were discussed:
1. How does mapper support "host"?
IPP to LPD; set H to mapper host
LPD to IPP, ignore H
2. job-k-octets semantic change between IPP and LPD (which includes copy
count?).
Just do the mapping
3. Move to Job-ID vs. Job-URI
Needs to be resolved on the discussion list (see Model & Semantics
discussion
earlier).
4. Should IPP pick a format for queue status or make it dependent on each LPD
implementation? Further discussion on the DL.
a. ignore the problem
b. pick a format
c. make it MUST or SHOULD
5. This mapping document is an INFORMATIONAL RFC, not an IMPLEMENTATION RFC
6. Should DVI, ditroff, or troff should be added as document-format types?
If we make them MIME types, then anyone can add them that wants them.
7. Open issue about mapping LPD to IPP error codes.
The chairs made clear that the intent of the WG is to move current I-Ds to
final
call in September 1997.
-----
El Segundo, September 11, 1997 - Carl-Uno Manros - IPP Co-chair
Carl-Uno Manros
Principal Engineer - Advanced Printing Standards - Xerox Corporation
701 S. Aviation Blvd., El Segundo, CA, M/S: ESAE-231
Phone +1-310-333 8273, Fax +1-310-333 5514
Email: manros at cp10.es.xerox.com