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

I am almost done with my reply. I wasn't ignoring Dale, I've beenworking on his comments.


At 11:28 PM +0000 2/21/17, Natasha Rooney wrote:

Hi Dale! Many thanks for these comments, as one of the SLIM chairsI'll work on getting some answers to you or I'll request the authoror one of the SLIM active participants to respond.

Bernard, Randall and SLIM - see below re Dale's points.


 **** A. Call failure ****

Randall or Bernard can you respond to this? I imagine the UA callfailure method is UA specific, but if there is a clash with SIPlevel call fail then this should be addressed.


 **** B. Audio/Video coordination ****

I believe the theory behind the current draft is that the spokenand video streams will be different in the cases of such things assign language. Video could therefore be sign and audio would be aspoken language. I'm not sure if the suggestion he satisfies thiscase?


 **** C. "humintlang" seems long to me ****

Bernard - I don't see the issue with shortening humintlang, but thegroup might. I suggest we throw this to the group for discussion.


 **** D. Use the Accept-Language syntax ****

Randall and Bernard - is this an acceptable change? Or one we needto discuss further. Seems like a reasonable request, but also alarger change, which is why I ask!

**** E. Have an attribute to abbreviate thebidirectionally-symmetric case ****I do not remember us having this discussion within the group,although it may have occurred before I became chair.Randall, Brian or Bernard - has this idea been discussed before? Ifso, can one of you respond with an explanation as to why we haven'tdone this?


 **** Editorial comments and nits *****

Randall - can you take a look through Dale's editorial comments andshout if there is any problems with these suggestions; ifeverything is ok please make the changes.


 Thanks all!

On 18 Feb 2017, at 02:32, Dale Worley<<mailto:worley(_at_)ariadne(_dot_)com>worley(_at_)ariadne(_dot_)com> wrote:

Reviewer: Dale Worley
Review result: Ready with Nits

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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?

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 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?

 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.

 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.

 * 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".

 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.

   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.

   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.

 Perhaps s/in-common/shared/.

   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.

   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.

 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".

 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".

 5.  Proposed Solution

 Perhaps /Proposed Solution/Solution/, since once this draft is
 approved, it becomes the solution.

 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 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.

   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/.

 Could you be more accurate by
 s/or in some cases/or for unidirectional streams/?

 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.

 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

 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.

 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 ...

 [END]

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