Re: [clue] Gen-ART review of draft-ietf-clue-telepresence-requirements-06.txt

[Mary Barnes <[e-mail]>]

Responses below [MB].

Mary.

On Thu, Dec 5, 2013 at 1:36 PM, Michael Hammer <[e-mail]
> wrote:

> Mary,
>
>
>
> What is the process here?
>
> The earlier comments imply that further changes may be needed and possible.
>
[MB] The process is standard IETF document progression process:
http://www.ietf.org/about/process-docs.html

The WG completes WGLC (which was completed for this doc on Sunday, Sept.
29th).  Then the document shepherd completes the write-up, reflecting that
the WG believes the document is ready to progress - that was done on
October 24th, 2013.  The AD then reviews the write-up and decides whether
the doc is ready for IETF Last Call.  The IETF Last Call for this document
started on October 30th and  lasted 4 weeks due to overlap with the IETF
meeting. Note, you can find all this information in the data tracker:
http://datatracker.ietf.org/doc/draft-ietf-clue-telepresence-requirements/
They've added a lot of nice new features that you might find handy,
including a link to Search the mailing list for any threads related to this
document as well as the History of it's progression through the IETF
process.

This email thread and any suggested changes are based upon the Gen-ART
review by Dan Romascanu during IETF Last Call.  We brought the discussion
to the WG mailing list since the changes are slightly more than editorial
and we cannot make the changes without ensuring the WG is okay with them.

Your comments arrived after IETF Last Call completed.  Certainly, if
someone finds something in a WG document that is terribly broken, they
should be brought to the attention of the WG, but I don't think this
comment fits in that category. [/MB]

Now, you say no changes are possible?
>
[MB] What I'm saying is that this change does not seem necessary.  It
doesn't add clarity and the requirement as it is doesn't takeaway from the
document.  I haven't dug back through email threads to see why this
requirement was added in the individual -03 - you might want to do that and
you might find visiting the email archives related to the development of
this document in the WG quite informative.   Everyone in the WG had
*plenty* of time to review this WG document over the past 2.5 years (the
-03 version where this requirement first appeared was published in June of
2011.  After a document leaves the WG, one should always be conservative
with regards to changes. [/MB]

> What was the point of posting on the email list?
>
[MB] See Above. [/MB]

> Or, is it only comments from the anointed?
>
[MB] See above - the comments being considered are those that were sent
during IETF Last Call. Your comments came after the completion of IETF Last
Call. Typically comments that late in the cycle are not always incorporated
unless there is a very compelling reason.  I personally don't see that
there is here. [/MB]

> The anointed are free to use my comments how they like by the way.  :)
>
[MB] And, that would the WG - if the WG decides that this change should be
made after IETF Last Call - as noted,  typically WGs want to be
conservative about changes at this stage unless there is a really
compelling reason. [/MB]

>
>
> I would also argue since the text is redundant,
>
[MB] I don't at all see it as entirely redundant.  It might be implying the
same requirement, but it is also clearly spelling out requirements explicit
to presentation, which are also related to requirements for other media.
[/MB]


> it is editorial change to remove to make the document clearer.
>
[MB] I actually believe it makes the document clearer by being very
explicit as to the requirements associated with the presentation use case.
[/MB]

>
>
> Mike
>
>
>
>
>
> *From:* Mary Barnes [mailto:[e-mail]]
> *Sent:* Thursday, December 05, 2013 2:09 PM
> *To:* Michael Hammer
> *Cc:* [e-mail]; [e-mail];
> [e-mail];
> [e-mail]
>
> *Subject:* Re: [clue] Gen-ART review of
> draft-ietf-clue-telepresence-requirements-06.txt
>
>
>
> HI Michael,
>
>
>
> Comments inline below [MB].
>
>
>
> Thanks,
>
> Mary.
>
>
>
> On Mon, Dec 2, 2013 at 2:34 PM, Michael Hammer <
> [e-mail]> wrote:
>
> Requirement 15 is written in language that is more vague than the other
> requirements.
>
> I would argue that what it says is already covered by the other
> requirements and could be removed with no harm.
>
> [MB] You have a reasonable point, but I would suggest that leaving this
> requirement also causes no harm. It's been in the document since the -00 WG
> version.  It was added as REQMT-16 in the individual -03.
>
> Please keep in mind that this document has completed IETF Last Call (we
> had consensus on this document in the WG a while back), so there would have
> to an extremely compelling reason and WG consensus to remove.
>
> [/MB]
>
>
>
> For example Reqts 2 and 4 seem to say that there will be multiple devices
> involved in creating a “presentation”.
>
> And 5-9 seem to cover various interop issues with different numbers and
> types of devices.
>
> Also, presentation is not defined.
>
> [MB] Given that we have an entire use case dedication to "presentation" I
> don't think the term needs to be defined in this document. However, it
> would probably be good to add the reference to the Presentation use case
> for REQMT-15 as we have done for some others.   [/MB]
>
>
>
> Mike
>
>
>
>
>
> *From:* clue [mailto:[e-mail]] *On Behalf Of *Duckworth, Mark
> *Sent:* Monday, December 02, 2013 3:11 PM
> *To:* Stephen Botzko; Mary Barnes
>
>
> *Cc:* [e-mail];
> [e-mail]
> *Subject:* Re: [clue] Gen-ART review of
> draft-ietf-clue-telepresence-requirements-06.txt
>
>
>
> Comments inline.
>
> Mark Duckworth
>
>
>
> *From:* clue [mailto:[e-mail]] *On Behalf Of *Stephen Botzko
> *Sent:* Wednesday, November 27, 2013 5:28 PM
> *To:* Mary Barnes
> *Cc:* [e-mail];
> [e-mail]
> *Subject:* Re: [clue] Gen-ART review of
> draft-ietf-clue-telepresence-requirements-06.txt
>
>
>
> Dan - thanks so much for reviewing this.
>
> Comments are in-line
>
>
>
> Stephen Botzko
>
>
>
> On Thu, Nov 21, 2013 at 4:39 PM, Mary Barnes <[e-mail]>
> wrote:
>
> On Thu, Nov 21, 2013 at 10:38 AM, Paul Kyzivat <[e-mail]>
> wrote:
>
> Authors,
>
> What do you think of these comments?
> If you aren't in agreement with all of them, then we should have a dialog
> with Dan about them.
>
> If in agreement, then lets discuss what changes are appropriate.
>
> More inline.
>
>
>
> On 11/21/13 7:08 AM, Romascanu, Dan (Dan) wrote:
>
> I am the assigned Gen-ART reviewer for this draft. For background on
> Gen-ART, please see the FAQ at
>
> <http://wiki.tools.ietf.org/area/gen/trac/wiki/GenArtfaq>.
>
> Please resolve these comments along with any other Last Call comments you
> may receive.
>
> Document: draft-ietf-clue-telepresence-requirements-06.txt
> Reviewer: Dan Romascanu
> Review Date: 11/21/13
> IETF LC End Date: 11/27/13
> IESG Telechat date: (if known)
>
> Summary: It's a good and well written document, almost ready, but a number
> of issues should be clarified before approval.
>
> Major issues:
>
> 1. The definitions of Left and Right in Section 3 use an entry article in
> Wikipedia ('Stage Directions'). I am both uncomfortable with the usage of
> Wikipedia articles (subject to change, subject to attacks) as references,
> and I also believe that the current definitions (@11/21/13, US morning
> hours) are ambiguous. Actually the Wikipedia article does not include
> definitions for Left and Right, and speaks about 'house left' (equal to
> 'stage right') and 'house right' (equal to 'stage left'). If another
> specification in CLUE will use the terms defined here it is not clear which
> one is meant.
>
>
>
> This seems like a reasonable point to me. Is there a more stable reference
> we can use? If not, can we just define these terms in the document?
>
> [MB] I'm almost of a mind to just remove those definitions.  The consensus
> was that the terms should be qualified when they are used and the framework
> does an excellent job of defining more precise terms that properly qualify
> "left" and "right" and differentiate from stage right, etc. as appropriate.
>  We use "left" and "right" in one place in this requirements document and I
> think the use is general enough that we don't need a definition (in this
> document).   The wikipedia reference has been in the document since day 1
> as a WG document (it was added in -03 of the individual document).   The
> discussions around "left"/"right" on the list were in the context of the
> definitions document and again, consensus was that the terms should be
> qualified (as they are in the framework), thus I don't think the current
> definitions serve any value. [/MB]
>
> [SB] I agree with Mary that these definitions can simply be removed.
> [/SB]
>
> *[Duckworth, Mark] I agree too.*
>
>
>
> 2. In REQMT-1d it is not clear what 'the extent of individual video
> captures' means
>
> 3. In REQMT-2d it is not clear what 'the extent of individual audio
> captures' means
>
>
>
> We have had our own concerns about this. I think we want to say
> *something* but its unclear to me exactly what. Perhaps we could focus on
> what we want to use this for, and explicitly leave details of what it is
> for the FW.
>
> [MB] Can you point to the threads of discussion where you feel this
> concern with this phrasing has been raised?   There were certainly concerns
> raised about those requirements (i.e., 3D), but I'm not reading this as
> Dan's concern.   My understanding is that the word "extent" is used in the
> context of video imagery from the perspective of the camera - i.e., the
> "angular extent" or something like that.  I think we should replace the
> word "extent" with something more specific.  Anyone have a suggestion?
>
> [SB]
>
> The intent of REQMT-1d was to say that CLUE needs to identify the area
> that each camera captured in the room - so it would be clear how views from
> different camera related to each other, and also if there were any gaps,
> etc.  Identifying the scale of the view is related, but is captured
> concisely in requirement 6.  Proper rendering in a multi-camera
> telepresence system requires this knowledge - today it is generally
> hard-wired into the room design.  But that doesn't result in an
> interoperable experience, and it needs to be signaled if you want to get
> appropriate rendering between rooms with disparate designs.
>
>
>
> For audio [REQMT-2d], there is an analogous need to identify the area of
> coverage of a microphone.  The need to correlate the audio and the video is
> related, but is captured separately in REQMT-3.
>
>
>
> The discussions on the list related to audio and video area of coverage
> were about whether the model in the framework was adequate.  Personally I
> believe it is.  But what really matters here is whether we are clearly
> stating the *requirement*, not the adequacy of the proposed
> specifications.
>
> One alternative term is "area of coverage", which is commonly used in
> surveillance applications to describe a similar concept.  If people think
> that might be confused with radio coverage (e.g. an LTE coverage map) we
> could draft a definition and add it to section 3.
>
> [/SB]
>
> *[Duckworth, Mark] I agree with Steve about the intent.  I agree “area of
> coverage” is a better term than “extent” for this purpose.*
>
>
>
>
>
> And, note these requirements were added based on discussion at IETF-82:
>
> http://www.ietf.org/proceedings/82/slides/clue-1.pdf
>
>
>
>  [/MB]
>
>         Thanks,
>         Paul
>
>
>
> 4. REQMT-10: The solution MUST make it possible for endpoints without
>                support for telepresence extensions to participate in a
>                telepresence session with those that do.
>
> More clarity is needed to explain what level of participation in a session
> (and what limitations) are expected from endpoints that do not support the
> telepresence extensions. I assume there are limitations, otherwise
> extensions would not be needed.
>
> [SB] The intent was to simply state that the solution must not prevent
> direct interoperability with SIP devices (either phone or
> videoconferencing) - without the need for a middlebox to convert signaling
> (as would be required with rtcweb for instance).   The limitation is simply
> that telepresence extensions can't be used.  I do not see a need to
> describe the limitations of existing SIP systems in this requirements
> document.
>
> Suggested text that makes the requirement more clear would be helpful.
> This is a bit tricky to word, since SIP itself has no requirement that says
> SIP endpoints must interoperate with each other w/o middleboxes to assist.
> And in fact they often don't.  We could alternatively drop the requirement.
>
> [/SB]
>
> *[Duckworth, Mark] I agree with Steve about the intent.  How about
> something like “The solution must make it possible for devices that support
> CLUE to interoperate directly with SIP devices that do not support CLUE” ?*
>
>
> 5. REQMT-15 (last bullet): I could not really figure out what is meant here
>
> *  There can be variation in placement, number and size of
>                   presentations
>
> [SB]At this point I am not certain either.  We might have meant that
> different use cases had different placements, number, and size of
> presentations. Or that existing telepresence systems handle presentations
> in different ways.
>
> It is not worded as a clear requirement, and it says "can", not "should"
> or "must".  My recommendation is to delete that bullet.
> [/SB]
>
> *[Duckworth, Mark] I think we meant this:*
>
>             * - There can be multiple simultaneous presentation media
> streams*
>
>             *- Presentation media streams can be spatially related to
> each other*
>
>
>
> 6. REQMT-16:  The solution MUST include extensibility mechanisms.
>
> What 'extensibility' is meant here? Extending the telepresence sessions,
> or extending the specifications for new functionality in the future?
>
> [SB] What is meant is extending the specifications for new functionality
> in the future.  I suggest that we re-word to "New protocols developed for
> the solution MUST include extensibility mechanisms"
> [/SB]
>
> *[Duckworth, Mark] Steve’s suggestion is more clear.*
>
>
>
> Minor issues:
>
> 1. If this is the first and basic document to be read by somebody who
> starts to browse through the CLUE specifications, it would be good to
> define or expand some place in the introduction what CLUE is.
>
> [SB] I am not sure if the CLUE WG has a recommended order for reading the
> various documents.  Personally I would recommend that people start with the
> use cases.  In any event, I think the document purpose is properly captured
> in the abstract - it is not intended to be an introduction to telepresence
> generally or as an orientation to CLUE specifications.
> [/SB]
>
> *[Duckworth, Mark] I agree.*
>
>
>
> 2. In the Introduction Section I see:
>
>   These
>
>     requirements are for the specification, they are not requirements on
>     the telepresence systems implementing the solution/protocol that will
>     be specified.
>
> But then all requirements in section 5 start by 'The solution ...' which
> is ambiguous. It would be good to mention (again) in section 5 that by what
> is meant by the 'solution' is the definition of the protocol, not the
> implementation.
>
> [SB] I agree.  We should also use "specifications", since current plans
> call for more than one standards-track RFC
> [/SB]
>
> *[Duckworth, Mark] I agree*
>
>
> 3. I will defer to the Security Review to comment whether REQMT-18 is
> enough from a security point of view - especially as the information about
> media captures may include explicitly or implicitly details about equipment
> on each site, etc. To me it seems a little bit too vague.
>
> [SB] I don't see it as vague - it pretty clearly says that only the
> mechanism needs to be secure.  I think you are saying that the security
> section might be incomplete.
>
> Current protocol designs do not include explicit details about equipment,
> and I see nothing in the requirements that suggest otherwise.  Some
> requirements do require transport of information that can be used infer
> room dimensions (at least of the visible portion of the room) and the
> audio/video coverage within it.  Can you identify threats that might use
> that information?
>
> Of course each specification includes its own Security Considerations.
> Obviously we will address any security review comments in this one.
> [/SB].
>
>
> Regards,
>
> Dan
>
>
>
>
>