Re: [Slim] Review of draft-ietf-slim-negotiating-human-language-06

[Gunnar Hellström <[e-mail]>]

A few comments inline,


Den 2017-02-22 kl. 02:44, skrev Randall Gellens:
> Hi Dale,
>
> Thank you for your review, I appreciate it.  Please see inline.
>
> At 6:32 PM -0800 2/17/17, Dale Worley wrote:
>
>>  Reviewer: Dale Worley
>>  Review result: Ready with Nits
>>
>>  I am the assigned Gen-ART reviewer for this draft.  The General Area
>>  Review Team (Gen-ART) reviews all IETF documents being processed
>>  by the IESG for the IETF Chair.  Please treat these comments just
>>  like any other last call comments.
>>
>>  For more information, please see the FAQ at
>>  <http://wiki.tools.ietf.org/area/gen/trac/wiki/GenArtfaq>.
>>
>>  Document:  draft-ietf-slim-negotiating-human-language-06
>>  Reviewer:  Dale R. Worley
>>  Review Date:  2017-02-17
>>  IETF LC End Date:  2017-02-20
>>  IESG Telechat date:  [unknown]
>>
>>  Summary:
>>         This draft is basically ready for publication, but has nits
>>         that should be fixed before publication.
>>
>>  * Technical comments
>>
>>  A. Call failure
>>
>>  If a call fails due to no available language match, in what way(s)
>>  does it fail?  Section 5.3 says
>>
>>     If such an offer is received, the receiver MAY
>>     reject the media, ignore the language specified, or attempt to
>>     interpret the intent
>>
>>  But I suspect it's also allowed for the UAS to fail the call at the
>>  SIP level.  Whether or not that is allowed (or at least envisioned)
>>  should be described.  And what response code(s)/warn-code(s) should
>>  be
>>  used for that?
>
> The text you quote has been deleted.  The draft does not mandate if 
> the call should proceed or fail if there is no language match 
> possible, although the draft does provide an optional mechanism to 
> indicate the caller's preference that the call not fail, and the draft 
> does mention that in the emergency services case, the call will likely 
> proceed, but that's a matter of policy not protocol.
You may have a version where it is proposed that the text is deleted. We 
need to see that new text and agree if it was good to delete it.

There are more places in the draft where failing the call is mentioned, 
so the question about how it is failed is relevant anyway. A 603 Decline 
from the proxy would likely be the natural way to fail the call when it 
is because of lack of matching languages. But I do not see any natural 
way for an addressed UA to signal this.

>
>>
>>  B. Audio/Video coordination
>>
>>     5.2.  New 'humintlang-send' and 'humintlang-recv' attributes
>>
>>     Note that while signed language tags are used with a video stream
>>  to
>>     indicate sign language, a spoken language tag for a video stream
>>  in
>>     parallel with an audio stream with the same spoken language tag
>>     indicates a request for a supplemental video stream to see the
>>     speaker.
>>
>>  And there's a similar paragraph in 5.4:
>>
>>>     A spoken language tag for a video stream in conjunction with an
>>  audio
>>>     stream with the same language might indicate a request for
>>>     supplemental video to see the speaker.
>>
>>  I think this mechanism needs to be described more exactly, and in
>>  particular, it should not depend on the UA understanding which
>>  language tags are spoken language tags.  It seems to me that a
>>  workable rule is that there is an audio stream and a video stream and
>>  they specify exactly the same language tag in their respective
>>  humintlang attributes.  In that case, it is a request for a spoken
>>  language with simultaneous video of the speaker, and those requests
>>  should be considered satisfied only if both streams can be
>>  established.
>
> The text you quote has been deleted.  A media stream for supplemental 
> purposes can be negotiated without a language tag, as normal.
>
The text should not be deleted just because it is under discussion.
It is a valid and valuable alternative. At the moment we lack ways to 
indicate if languages are wanted together or seen as separate 
alternatives, and we have said that such detailing can be added in 
future versions or additional specifications if not done now. Therefore 
we had better allow this combination and let the negotiating parties 
sort out what it currently means. The specification just indicates that 
the indicated languages are alternatives, and any number may be selected 
for matching and usage in the session.
I do not think we should require very exactly matching language tags 
between spoken language in audio and corresponding view of the speaker 
in video.
>>
>>  * The following three items are adjustments to the design which I'd
>>  like to know have been considered.
>>
>>  C. "humintlang" seems long to me
>>
>>  Given the excessive length of SDP in practice, it seems to me that a
>>  shorter attribute name would be desirable.  E.g., "humlang" as was
>>  used in some previous versions.  Or is there a coordinated usage with
>>  other names in the "hum*lang" pattern?
>
> There is no intent for a coordinated pattern.  The name was chosen 
> years ago to avoid potential confusion with the 'lang' attribute. Is 
> it worth reopening the issue to potentially save three characters per 
> SDP line with a language?
>
>>
>>  D. Use the Accept-Language syntax
>>
>>  It seems to me that it would better to use the Accept-Language syntax
>>  for the attribute values.  This allows (1) specifiying the quality of
>>  language experience, allowing clear description of bilingualism, (2)
>>  a
>>  unified method of specifying whether or not arbitrary languages are
>>  acceptable, and (3) abbreviating SDP descriptions.
>>
>>  In a way, the fact that the current proposal seems to require (but
>>  does not directly specify) the coordinated absence/presence of an
>>  asterisk on all of the repetitions of humintlang-send or
>>  humintlang-recv is a warning that the syntax doesn't represent the
>>  semantics as well as it might.
>
> The group considered multiple proposals to permit specifying quality, 
> preference, q-values, etc. but decided to keep things simple for this 
> draft.  There is no intent to require the use of an asterisk (to 
> indicate a preference by the caller to not fail the call).  The 
> asterisk is a very mild mechanism with no normative effects.  It 
> merely conveys the preference of the caller, and is not binding on the 
> answerer.
I would never dare to use an sdp without an asterisk. Language matching 
is a tricky thing and human capabilities much wider than the language 
tags can express. If I get a call from a Norwegian user talking 
Norwegian and indicating Norwegian in the humintlang attributes, I want 
to get the call accepted by my device with setting for spoken Swedish, 
because Swedes and Norwegians usually can communicate quite well 
speaking their own languages. I would anyway not have imagined making a 
setting for Norwegian language as a preference in my device.
It will however be an excellent help for me to see the indication of the 
Norwegian, when I get the call, so I can tune my listening.
By setting the asterisk somewhere among the Humintlang attributes, I 
will make sure that I do not lose calls that I could handle.

>
>>  E. Have an attribute to abbreviate the bidirectionally-symmetric case
>>
>>  Note that all examples are bidirectionally symmetric, and the text
>>  says that requests and responses SHOULD be bidirectionally symmetric.
>>  So it would be a very useful abbreviation to define
>>  "humintlang=<value>" to be equivalent to the combination of
>>  "humintlang-send=<value>" and "humintlang-recv=<value>".
>>
>>  Combining proposals C, D, and E, the examples become
>>
>>        m=audio 49170 RTP/AVP 0
>>        a=humlang:en
>>
>>        m=video 51372 RTP/AVP 31 32
>>        a=humlang:ase,*;q=0.1
>>
>>        m=audio 49250 RTP/AVP 20
>>        a=humlang:es,eu;q=0.9,en;q=0.8,*;q=0.1
>>
>>        m=text 45020 RTP/AVP 103 104
>>        a=humlang:gr
>>
>>  which requires about half as many characters as they have now.
>
> A third attribute without the "-send" or "-recv" to indicate 
> bidirectionality would reduce the characters in the SDP block, at the 
> cost of some added complexity (e.g., what if all three appear).  I 
> don't believe this has been discussed in the group.
>
>>  * Editorial comments and nits
>>
>>  Abstract
>>
>>     This document describes the need and a solution using new SDP
>>  stream
>>     attributes.
>>
>>  I don't think the term "stream attribute" is used in RFC 4566.
>>  Instead, it uses "media attribute".
>
> Fixed.
>
>>  1.  Introduction
>>
>>     caller and callee know each other or there is contextual or out of
>>     band information from which the language(s) and media modalities
>>  can
>>
>>  I think this context, it's preferred to hyphenate "out-of-band" to
>>  make it clearly be an adjective.
>
>>  OK.
>
>
>>     This approach has a number of benefits, including that it is
>>  generic
>>     (applies to all interactive communications negotiated using SDP)
>>  and
>>     not limited to emergency calls.
>>
>>  I think s/and not limited to/and is not limited to/ reads more
>>  smoothly.
>
> There's no harm in the extra "is" so I'm happy to add it.
>
>>     But it is clearly useful in many other cases.  For
>>     example, someone calling a company call center or a Public Safety
>>     Answering Point (PSAP) should be able to indicate if one or more
>>     specific signed, written, and/or spoken languages are preferred,
>>  the
>>     callee should be able to indicate its capabilities in this area,
>>  and
>>     the call proceed using in-common language(s) and media forms.
>>
>>  I think s/preferred, the callee/preferred; the callee/ because the
>>  sentence is the concatenation of two sentences.
>
> I reworded the sentence to flow better:
>
>    For example, it is helpful that someone calling a company call center
>    or a Public Safety Answering Point (PSAP) be able to indicate
>    preferred signed, written, and/or spoken languages, the callee be
>    able to indicate its capabilities in this area, and the call proceed
>    using the language(s) and media forms supported by both.
>
>>  Perhaps s/in-common/shared/.
>
> Fixed in the rewording above.
>
>>
>>     Including the user's human (natural) language preferences in the
>>     session establishment negotiation is independent of the use of a
>>     relay service and is transparent to a voice service provider.
>>
>>  I think it's even broader than "transparent to a voice service
>>  provider" -- it's transparent to any serivice provider, assuming that
>>  the media are language-neutral.
>
> I changed it to read "voice or other service provider".
>
>>
>>     In the case of a call to e.g., an airline, the call could be
>>     automatically handled by a Spanish-speaking agent.
>>
>>  I think s/handled by/routed to/ is the usual usage.
>
> We are trying to be careful in the draft to not imply that it is 
> discussing call routing.  I'd rather keep the more generic "handled by".
>
>>
>>  3.  Desired Semantics
>>
>>     The desired solution is a media attribute (preferably per
>>  direction)
>>     that may be used within an offer to indicate the preferred
>>  language
>>     of each (direction of a) media stream, and within an answer to
>>     indicate the accepted language.
>>
>>  In this one instance, I think you want to use "language(s)" to drive
>>  home that that multiple languages can be specified:  "within an offer
>>  to indicate the preferred language(s)".
>>
>>     (Negotiating multiple simultaneous languages within a media stream
>>  is
>>     out of scope, as the complexity of doing so outweighs the
>>     usefulness.)
>>
>>  You might want to say instead "(Negotiating multiple simultaneous
>>  languages within a media stream is out of scope for this document.)"
>>  to ensure that nobody decides to argue whether "the complexity of
>>  doing so outweighs the usefulness".
>
> I agree and deleted "the complexity of doing so outweighs the 
> usefulness".
>
>>
>>  4.  The existing 'lang' attribute
>>
>>     RFC 4566 [RFC4566] specifies an attribute 'lang' which appears
>>     similar to what is needed here, but is not sufficiently detailed
>>  for
>>     use here.
>>
>>  "for use here" isn't quite right.  Maybe "is not sufficiently
>>  specific
>>  or flexible to satisfy the requirements".
>>
>>     In addition, it is not mentioned in [RFC3264]
>>
>>  "it" is somewhat ambiguous here, perhaps change to "the 'lang'
>>  attribute".
>
> OK, accepted both changes.
>
>>
>>  5.  Proposed Solution
>>
>>  Perhaps /Proposed Solution/Solution/, since once this draft is
>>  approved, it becomes the solution.
>
> OK.
>
>>
>>  5.2.  New 'humintlang-send' and 'humintlang-recv' attributes
>>
>>        a=humintlang-send:<language tag>
>>        a=humintlang-recv:<language tag>
>>
>>  This is presented as the generic form of the attributes, but there is
>>  no indication of the posible asterisk.
>
> The syntax has been deleted from 5.2 since it's now in 6.
I think it should not be deleted, but instead Dale's comment satisfied.  
That would be more in line with the stye of rfc4566bis.
5.2 shows the complete attributes, and that is good. Chapter 6 only 
shows the syntax of the value.
>
>>
>>     The values constitute a list of languages
>>     in preference order (first is most preferred).
>>
>>  "The values" isn't very clear, because the values are in successive
>>  attributes.  You want to say something like "The sequence of values
>>  in
>>  the occurrences of one of these attributes constitutes ...".
>>  However,
>>  see the technical comments above.
>
> The text was reworded to read:
>
>    The values from all
>    instances of the attribute constitute a list of languages in
>    preference order (first is most preferred).
>
>
>>
>>     When placing an emergency call, and in any other case where the
>>     language cannot be assumed from context, each media stream in an
>>     offer primarily intended for human language communication SHOULD
>>     specify both (or in some cases, one of) the 'humintlang-send' and
>>     'humintlang-recv' attributes.
>>
>>  Probably s/assumed/inferred/.
>
> I agree.
>
>>
>>  Could you be more accurate by
>>  s/or in some cases/or for unidirectional streams/?
>
> I agree.
>
>>
>>  5.3.  Advisory vs Required
>>
>>     The mechanism for indicating this preference is that, in an offer,
>>  if
>>     the last character of any of the 'humintlang-recv' or 'humintlang-
>>     send' values is an asterisk, this indicates a request to not fail
>>  the
>>     call (similar to SIP Accept-Language syntax).  Either way, the
>>  called
>>     party MAY ignore this, e.g., for the emergency services use case,
>>  a
>>     PSAP will likely not fail the call.
>>
>>  The construction of this paragraph isn't quite complete.  It says
>>  that
>>  if an asterisk is present, a request shouldn't fail, but it doesn't
>>  say that if no asterisk is present, a request should fail if there is
>>  no language match.  And it's the latter condition that makes the
>>  second sentence meaningful.  So I think you want to insert between
>>  the
>>  two sentences one regarding the absence of an asterisk.
>
> I've reworded the section to read:
>
>    A consideration with the ability to negotiate language is if the call
>    proceeds or fails if the callee does not support any of the languages
>    requested by the caller.  This document does not mandate either
>    behavior, although it does provide a way for the caller to indicate a
>    preference for the call succeeding when there is no language in
>    common.  It is OPTIONAL for the callee to honor this preference.  For
>    example, a PSAP is likely to attempt the call even without an
>    indicated preference when there is no language in common, while a
>    call center might choose to fail the call.
>
>    The mechanism for indicating this preference is that, in an offer, if
>    the last character of any of the 'humintlang-recv' or 'humintlang-
>    send' values is an asterisk, this indicates a request to not fail the
>    call.  The called party MAY ignore the indication, e.g., for the
>    emergency services use case, regardless of the absence of an
>    asterisk, a PSAP will likely not fail the call; some call centers
>    might reject a call even with an asterisk.
This still does not meet Dale's comment.
Insert a sentence saying:
"A preference for getting the call denied in case of no language match 
SHOULD be indicated by no asterisk appended on any humintlang attribute 
value in the whole SDP."
>
>>  5.5.  Examples
>>
>>  Given that the combined audio/video mechanism is the only
>>  irregularity
>>  in this system, there ought to be an example of it.  E.g.,
>>
>>     An example of a supplemental video stream with a spoken language
>>     audio stream:
>>
>>        m=video 51372 RTP/AVP 31 32
>>        a=humintlang-send:en
>>        a=humintlang-recv:en
>>
>>        m=audio 49250 RTP/AVP 20
>>        a=humintlang-send:en
>>        a=humintlang-recv:en
>
> If the video stream is supplemental then it doesn't have a language 
> (the text that suggested otherwise has been deleted). But I am 
> considering adding more examples.
I provided a rich set of examples in my LC comments of Feb 13. Please 
consider them as a base even if some need revision if the proposed 
extended meaning of the asterisk is not accepted.
>
>>
>>  6.  IANA Considerations
>>
>>        humintlang-value =  Language-Tag [ asterisk ]
>>                            ; Language-Tag defined in RFC 5646
>>        asterisk         =  "*"
>>
>>  s/Language-Tag defined in RFC 5646/Language-Tag as defined in RFC
>>  5646/
>>
>>  But perhaps also s/RFC 5646/BCP 47/, which ensures that "humintlang"
>>  tracks the current version of language tags.
>
> Ok.
>
>>
>>  Appendix A.  Historic Alternative Proposal: Caller-prefs
>>
>>     This
>>     results in a more fragile solution since the media modality and
>>     language would be negotiated using SIP, and then the specific
>>  media
>>     formats (which inherently include the modality) would be
>>  negotiated
>>     at a different level (typically SDP, especially in the emergency
>>     calling cases), making it easier to have mismatches (such as where
>>     the media modality negotiated in SIP don't match what was
>>  negotiated
>>     using SDP).
>>
>>  "the media modality and language would be negotiated using SIP" isn't
>>  quite the right way to say it because SIP isn't explicitly
>>  negotiating
>>  the modality.  Better would be
>>
>>     ... the language (and by implication the media modality) would be
>>     negotiated using SIP, and then the specific media (which
>>  inherently
>>     include the modalities and formats) would be negotiated at a
>>     different level ...
>
> This section has been deleted.
Did we agree on that?
>
>>
>>  [END]
>
>
Regards
Gunnar

-- 
-----------------------------------------
Gunnar Hellström
Omnitor
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