IPP> Issues List

IPP> Issues List

IPP> Issues List

Scott Isaacson Scott_Isaacson at novell.com
Wed Dec 4 13:11:37 EST 1996

I have gone back through all the e-mail and made an issues list of things
that have come up and need to be fomally worked or closed.  I have not
included the Issues from the I-D.   I propose that we should assign an
owner to each of these and expect to get some closure.  Some are
pretty crisp, others are much more vague.  I probably have missed some.

I have posted "issues961204.(doc, pdf, ps, and txt) " in the ftp server.   I
have included the txt inline in this message.
Carl-Uno, as chair do you want to track any of these as work items?  Do
you want a process where someone can "raise and issue" and have it
formally recorded somewhere or just via e-mail discussions?



            1. What is our relationship to Internet Fax?   What is their
               final charter?  What is our final charter?  Are there any
               other groups that we need to liaison with?

            2. Randy suggested looking at draft-ietf-asid-string-filter-
               v2-00.txt.  Did any one review this  and have comments
               about IPP use of LDAP?

            3. On 11/14/96, Roger posted htppnew.ps.  Has this been
               reviewed and incorporated?

            4. Have we resolved the issue of  "Extending HTTP vs. Use
               Existing HTTP Methods*

               Larry Masinter:
               What would help is to have a specific proposal of how to
               ># HTTP to have the following DPA/LDPA operations:
               >#    SubmitJob
               >#    CancelJob
               >#    ListJobAttributes
               >#    ModifyJob
               >#    ResubmitJob
               >This is similar  to the discussion  we're having  in the
               >Authoring and  Versioning"  group,  which is  trying  to
               build a profile
               >for doing document management  at web sites  (e.g., such
               as FrontPage,
               >MKS Source Integrity, Documentum,  etc. are doing).   In
               that group, as
               >here, the  issue  is:  New  methods,  or POST  with  new
               >    You might  want to look  at the  home page  for that
               working group:
               >   http://www.ics.uci.edu/~ejw/versioning/
               >SubmitJob could  easily be  a POST  which returns  a job
               attributes and a
               >Location: header that is the Job URL. CancelJob could be
               done with a
               >DELETE of the Job URL, ListJobAttributes might be GET of
               the Job URL,
               >ModifyJob could be a PUT of  the Job URL with  a new set
               of Job
               >Attributes (or  Post).  I  don't know  what  ResubmitJob
               might be, but
               >perhaps it's a POST too.

               Henning commnets:

               The MMUSIC group is currently  considering extending HTTP
               for conference
               control (see  my  RTSP  draft and  a  yet-to-be-published
               initiation draft). We'll  discuss this  with the  HTTP WG
               chair, but our
               impression is  that extending  HTTP does  not necessarily
               imply changing
               the base  draft.  The advantage  is  conciseness and  the
               immediate ability
               to extend web servers to do the job.  Your method is then
               a "first-class
               citizen", with  appropriate access  control, query  about
               existing methods,

            5. Are there any data transfer issues associated with
               running IPP over HTTP/1.0?  Can the contents of a POST be
               arbitrarily large (several documents of many Mb each)?

            6. On 11/15/96, Roger posted  ipp-http-stuff.doc has this
               been reviewed or incorporated?

            7. Have we resolved all of the Attribute Syntax issues?

            8. Do we need to add a fan in picture back into the

            9. Some directory entry attributes are set by the Printer.
               Some are set by the Administrator?  Do we know which are
               which?  Do we care?

               Notes from Kieth:   The original set of Printer object
               attributes were hardware-oriented i.e.   a Printer
               object that is really a physical printer could specify
               these   attributes.  Per our phone call, there are  now
               attributes (i.e. "speed", "quality" or "cost" = "high",
               "medium", "low") that an administrator -   not a physical
               printer - must specify i.e. It seems that an
               administrator   must determine how to assign "high",
               "medium" or "low" to "speed",   "quality" and "cost"
               while a printer can only return its actual speed and
               resolution upon which the administrator determines the
               appropriate   attribute value.  "Location" can be
               specified and stored in some - but   not all - printers
               so in some cases the "location" attribute must also be
               specified by an administrator.  I believe the "speed",
               "quality", "cost"   and "location" attributes help the
               user more easily locate Printer   objects.  The point is
               there are now attributes for a Printer object   directory
               entry some of which are defined by the hardware and
               others by  the administrator.  A Printer object that is
               really a printer would only   add/modify the hardware

               attributes for its directory entry and not   add/update
               the administrator attributes for its entry.

            10.Where are we on the proposal to establish, through IANA,
               of a well known port (380 recommended) for printing via
               IPP over HTTP?

               Dons Comments: Dedicating a port to printing on the
               surface sounds good.  But, not
               being an expert on firewalls, I ask is that a problem?
               My understanding
               is that some firewalls keep things under control by not
               certains ports to be used (i.e. nothing can be used
               unless explicitly
               permitted.)  Is this going to be a problem in an inter-
               environment?  Could someone with a better understanding
               firewalls comment on this?

               Harry's comments:
               I would like to propose we attempt to standardize a well
               known port for
               printing via http. The notion would be that whatever we
               define as printing
               via http will work over http well known port 80 (along
               with everything else
               that flows via http), but, if directed to well known port
               (say 380 - assuming
               this port is not already defined), then only PRINTING,
               not any other form of
               http, would be expected.

               This proposal closely follows the motivation described in
               the internet draft
               <draft-mellquist-web-sys-00.txt> submitted June 1996,
               which recommends
               well known port 280 for SNMP over HTTP. Read (3) of this
               draft for a more
               thorough dissertation on the merits of this approach.

               As for text to add to the IPP draft (tonight), I suggest
               a new head level
               created between 2 (Distributed Printing) and 3 (IPP
               Objects) called
               2 (Printing via HTTP). Probably, a lot could be lifted
               from Roger's document
               and put into this section, I'm not going to try and flesh
               this out here.
               Also, in this section, however, we should put some words

                 "It will be suggested (in section 5) that Clients
               identify Printer objects
                 using an HTTP type URL. One element of this proposal
               will be to further
                 recommend the establishment, through IANA, of a well
               known port (380
                 recommended) for printing via HTTP. The purpose of this
               well known port
                 would be to distinguish printing from non-printing
               content. While any
                 acceptable HTTP content could be inter-mixed over HTTP
               well known port 80,
                 only HTTP printing would be acceptable on port 380.

                 The remainder of this draft will define the IPP content
               for HTTP printing,
                 including IPP objects, operations, naming and

               Carl-Uno comments:
               I brought up this subject with Larry Masinter (who is the
               IETF HTTP Chair)
               when I met him  last week. He  claims that the  HTTP does
               not really care about
               the port number and  that hence it  would be no  point in
               using a different
               number fore the printing protocol. Can somebody else, who
               is supplying Web
               servers, verify this?

               Jay comments:
               For the sake of global sanity,  IANA also registers ports
               above 1023, as
               I  recall.    So,   it's  probably  best   we  eventually
               coordinate through them
               if we are dealing on the Internet.

            11.We still have issues about Subjective values versu
               Objective values, especially in the Directory Entry.
               What is the set of values for each attribute?

            12.On 11/19/96, Roger posted some sample flows.  Is this
               what is in the current I-D?  Have we reviewed the
               encoding of content within an HTTP operation?

               Roger comments:
               Two things that I noted in doing this:

               My http proposal puts the document in a separate
               "container" rather than
               shipping it as an attribute as proposed in the current
               attribute write-up. I

               think this is preferable as it allows more structure of
               the data on the wire.
               This will make it easier to provide real document objects
               later on and add
               additional document attributes.

               As part of the above, I carry the document format in the
               header. This is more consistent with http, which puts
               mime-like content
               identifiers in all of its headers.

               I noted  that we have no attribute which describes the
               length of the queue.
               One of the main things that I look at when i personally
               submit print jobs is
               how busy the printer is.  If a printer is very busy, I
               find one hat is not so
               backed up.  What about an attribute called <jobs-in-

               Bob comments:
               After thinking about the protocol issue some more, it
               seems like there
               are two ways to organize the IPP Job Object in HTTP
               Protocol, the
               current proposal or my proposal described below.

               1) current proposal: The way proposed in the current
               document where the
               job and all document data is a part of a HTTP single

               2) my proposal: A job is an HTTP document whose top level
               content type
               is multipart/mixed (an existing type) or perhaps
               multipart/ipp (a new
               type and probably a bad idea).  In either case, the first
               entity has a
               content type of application/ippjob and contains the job
               Each remaining entity contains a document and they are
               all standard
               MIME types, such as application/PostScript or text/plain.
               Such a
               document could in the future become a
               multipart/ippdocument with a
               document attribute entity and a document content entity
               if a document
               has attribute overrides.  The document data entity could
               also have a
               content-type of multipart/alternative (an existing type)
               if a client

               wanted to have several representations of a document,
               e.g. HTTP and PDF
               and a printer supported such.

               The advantage of my proposal is that the document parts
               conventional MIME documents which any software could
               read. Only the
               application/ippjob and application/ippdocument require
               special software
               to process.

               Roger comment:
               Bob, I am not familiar enough with the real operation of
               HTTP protocols to know
               whether your idea is a good one or not.  I had thought
               that I could only send
               one enitity at a time, which would require leaving the
               connection open and
               turning the line around several times to complete
               transfer of the message when
               sending the document along with the print request.  How
               would this affect
               performance? Obviously this is not a concern when pulling
               the document later.

               What are the advantages of allowing "any" software to
               read the document data?
               Since I only apply the headers when sending the document
               to be printed I'm not
               sure what I gain?  In my proposal, the document content
               itself still has a
               standard Mime type

            13. What are we using for Device Id?

               Jay's comments:
               This issue/concept falls right into the same kind of
               discussion we
               recently conducted in the PWG regarding printer model
               particularly with regard to supporting print job
               submission and job
               formatting (ie, PPD-like file support, etc).

               Our experience tells us that users want to be able to
               view "real world"
               identification information, such as Make, Model and Type
               (although I'm
               not quite sure what "Type" would imply depending on the

               The previous related discussion pointed out that an OID
               must be provided
               to unambiguously and succinctly define the specific
               printer model; within
               the Printer MIB context, this value is defined as the
               hrDeviceID object
               in the HR MIB.  During the discussion someone questioned
               whether this was
               a workable solution, since the application would have to
               have knowledge of
               the OID mappings to determine the model type.  Those of
               us who develop
               such application software explained that the OID approach
               was indeed a
               reasonable solution, citing the need for a clean, simple
               syntax that has
               both hierarchical potential and distributed
               administration within the name
               space.  All of this is achieved via the standard SNMP SMI
               concept of the
               "Enterprises" tree.

               If we use a P1284 Device ID for the IPP, will these same
               naming features
               exist?  Can someone brief the PWG on the name space
               administration of
               the P1284 Device ID?  For example, how would an app
               developer know which
               vendors have which products registered for which IDs?

            14. What is the status of overlap with WEBDAV?

            15. What is the current write up on printer-name vs. URL and
               job-identifier vs URL?

            16. What is the current security story?

            17. Have we resolved all of the number-up, embellishments

            18. Are we cleared up on the Job Retention time issues
               (cancel, etc.)?

            19. What is the status of the shortest-job-first vs smallest-
               job-fisrt issue?

            20. Do we agree with the proposal to have no attributes that
               have no values?

            21. Was there a proposal to change the name of IPP due to
               other IPPs being found?

            22. Questions from reviewers:

               - I don't see any references to fan-fold paper anywhere.

               - It appears there is currently no suppurt fo accounting.
               One can
                 certainly argue that this is a function of security
               which you say
                 will be addressed later.

               - How do you plan to support color calibration and other
               features like
                 what is provided through PPD files?

               - I suspect that PostScript printing control (like
               spooling, status
                 queries, etc.) are not supported as part of the
                 Content-Type, right? It probably should be spelled out.

               HTTP methods are case-sensitive (HTTP/1.1, Section
               5.1.1); thus, your
               example needs updating

               - Wouldn't it make more sense to define a content-type:
               (or similar), so that the request would be a valid HTTP
               request? (The
               print request is then part of the entity).

               - Have you considered the alternative of defining a new
               method, say,
               PRINT, with entity headers appropriate for the new task?

            23. On 11/25/96 Roger posted an attribute summary.  Has this
               been reviewed?

            24. We need to clarify Job Templates.  Who wants to write up
               a new summary?  With examples?

            25. Has anyone reviewed  draft-mellquist-web-sys-01.txt?  Tom
               suggests that there is some overlap with Managment and

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