Re: [Slim] Eric Rescorla's No Objection on draft-ietf-slim-negotiating-human-language-19: (with COMMENT)
Eric Rescorla <ekr@rtfm.com> Mon, 08 January 2018 18:22 UTC
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From: Eric Rescorla <ekr@rtfm.com>
Date: Mon, 08 Jan 2018 10:22:11 -0800
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To: Randall Gellens <rg+ietf@randy.pensive.org>
Cc: Bernard Aboba <bernard_aboba@hotmail.com>, "slim@ietf.org" <slim@ietf.org>, Bernard Aboba <bernard.aboba@gmail.com>
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Subject: Re: [Slim] Eric Rescorla's No Objection on draft-ietf-slim-negotiating-human-language-19: (with COMMENT)
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WFM. thanks -Ekr On Mon, Jan 8, 2018 at 10:10 AM, Randall Gellens <rg+ietf@randy.pensive.org> wrote: > At 9:57 AM -0800 1/8/18, Randall Gellens wrote: > > At 9:48 AM -0800 1/8/18, Eric Rescorla wrote: >> >> On Mon, Jan 8, 2018 at 9:41 AM, Randall Gellens <<mailto: >>> rg+ietf@randy.pensive.org>rg+ietf@randy.pensive.org> wrote: >>> >>> At 5:56 PM -0800 1/7/18, Eric Rescorla wrote: >>> >>> On Sun, Jan 7, 2018 at 5:22 PM, Randall Gellens <<mailto:<mailto: >>> rg%2Bietf@randy.pensive.org>rg+ietf@randy.pensive.org><mailto:rg%2Bietf@ >>> randy.pensive.org>rg+ietf@randy.pensive.org> wrote: >>> >>> At 6:36 AM -0800 1/7/18, Eric Rescorla wrote: >>> >>> On Sat, Jan 6, 2018 at 7:31 PM, Bernard Aboba <<mailto:<mailto: >>> <mailto:bernard.aboba@gmail.com>bernard.aboba@gmail.com><mailto:bernard. >>> aboba@gmail.com>bernard.aboba@gmail.com><mailto:<mailto:bern >>> ard.aboba@gmail.com>bernard.aboba@gmail.com><mailto:bernar >>> d.aboba@gmail.com>bernard.aboba@gmail.com> wrote: >>> >>> On Jan 6, 2018, at 6:55 PM, Eric Rescorla <<mailto:<mailto:<mailto: >>> ekr@rtfm.com>ekr@rtfm.com><mailto:ekr@rtfm.com>ekr@rtfm.com><mail >>> to:<mailto:ekr@rtfm.com>ekr@rtfm.com><mailto:ekr@rtfm.com>ekr@rtfm.com> >>> wrote: >>> >>> For disabled users, the capabilities may not be symmetric. >>> >>> >>> But this is true for ordinary SDP as well. I might be able to >>> receive H.264 but not send it. >>> >>> >>> [BA] Thanks. The draft should explain the reasoning. IMHO the >>> argument goes sonething like this: >>> >>> A pure recv/recv negotiation will not necessarily disclose >>> beforehand what special services are needed for the call - services (e.g. >>> ASL interpretation or RTT handling) that could take time to acquire. >>> >>> Since the actual video media sent is not labelled as ASL even if the >>> answerer has ASL interpreters it can pull in and therefore advertises in >>> SDP ASL reception capability in video, a recv/recv negotiation doesn't tell >>> the Answerer that the Offerer will need them, so the Answerer may need to >>> (frantically) arrange for ASL interpretation after initial receipt of >>> media. In an emergency, that can chew up valuable time. >>> >>> >>> Thanks. I think it would be helpful to put this logic in the draft. >>> >>> >>> I am not clear on what logic we want to add to the draft, or what >>> about the draft this logic is explaining. >>> >>> >>> It would be helpful to explain in the draft why you have deviated >>> from the otherwise near-universal SDP negotiation pattern of each side >>> advertising what it accepts. >>> >>> >>> I'm not clear on what you're referring to. Are you talking about >>> early offer versus late offer? To my understanding, the draft follows a >>> typical offer/answer model: the caller lists the media and languages it >>> supports, and the callee answers with the media and languages it supports. >>> >>> >>> That's not what this draft does. The typical SDP pattern is what you >>> say here: that the offerer (which might or might not be the caller) lists >>> what it supports and the answerer lists what it supports. >>> So, for instance, the offerer might list "VP8, H.264" and the answerer >>> might respond with "VP8, H.264", at which point either side could use >>> either codec (or intermix them). What this draft does is have the offerer >>> list what it supports and the answerer picks exactly one. I understood from >>> the previous emails in the thread that the reason for this design was so >>> that each side then knew exactly what languages would be used. However, as >>> noted upthread, this draft does not provide this function if early media is >>> used, because the media is delivered to the offerer prior to receiving the >>> answer, so the offerer is in the same position as it would be with the >>> typical negotiation model. >>> >> >> Thanks, I think I understand your concern now. You'd like the draft to >> explain why the answer contains one language per media stream, which is >> partly for provide knowledge so both ends know what has been negotiated, >> but also because supporting languages and/or modalities may require taking >> extra steps, such as having a call handled by an agent who speaks a >> requested language and/or can use a requested modality, or bridging >> external translation or relay resources into the call, etc. The answerer >> indicates which additional steps it is committing to. These steps may or >> may not be in place in time for early media. I can add text explaining >> this to the Introduction. >> > > > The third paragraph below is the additional text added to the Introduction > (the first two paragraphs are unchanged): > > By treating language as another SDP attribute that is negotiated > along with other aspects of a media stream, it becomes possible to > accommodate a range of users' needs and called party facilities. For > example, some users may be able to speak several languages, but have > a preference. Some called parties may support some of those > languages internally but require the use of a translation service for > others, or may have a limited number of call takers able to use > certain languages. Another example would be a user who is able to > speak but is deaf or hard-of-hearing and and desires a voice stream > to send spoken language plus a text stream to receive written > language. Making language a media attribute allows the standard > session negotiation mechanism to handle this by providing the > information and mechanism for the endpoints to make appropriate > decisions. > > The term "negotiation" is used here rather than "indication" because > human language (spoken/written/signed) can be negotiated in the same > manner as media (audio/text/video) and codecs. For example, if we > think of a user calling an airline reservation center, the user may > have a set of languages he or she speaks, with perhaps preferences > for one or a few, while the airline reservation center will support a > fixed set of languages. Negotiation should select the user's most > preferred language that is supported by the call center. Both sides > should be aware of which language was negotiated. This is > conceptually similar to the way other aspects of each media stream > are negotiated using SDP (e.g., media type and codecs). > > In the offer/answer model used here, the offer contains a set of > languages per media that the caller is capable of using, and the > answer contains one language per media that the answerer will > support. Supporting languages and/or modalities can require taking > extra steps, such as having a call handled by an agent who speaks a > requested language and/or with the ability to use a requested > modality, or bridging external translation or relay resources into > the call, etc. The answerer indicates in the answer which additional > steps it is committing to. This model also provides knowledge so > both ends know what has been negotiated. Note that additional steps > required to support the indicated languages or modalities may or may > not be in place in time for any early media. > > > >> >>> >>> That said, as I noted in my review, it is still possible to get some >>> media (early media) prior to receiving the answer, so this isn't a complete >>> solution. >>> >>> >>> The draft provides a useful mechanism that will be helpful. As an >>> example of the fact that others find it useful, NENA has included it in >>> it's next-generation emergency call architecture standards. The draft does >>> not try to solve all problems related to human language in real-time >>> calling. >>> >>> >>> I don't think I claimed it wasn't useful. >>> >>> The rationale provided for this design is that you wish to have the >>> answerer notify the offerer of which language it would be providing. The >>> point I am making is that there is at least one important case where this >>> design does not provide that, which seems like it's relevant to the design >>> question. >>> >>> >>> I think I'm still not understanding your concern. Even without >>> providing a mechanism for the caller to know the languages used with any >>> early media, the draft is still meeting a need. >>> >>> >>> I'm honestly not sure what you're responding to here. I'm not saying >>> that the draft doesn't meet a need. >>> >>> -Ekr >>> >>> >>> >>> >>> -- >>> Randall Gellens >>> Opinions are personal; facts are suspect; I speak for myself only >>> -------------- Randomly selected tag: --------------- >>> Imagination is more important than facts. --Albert Einstein >>> >>> >>> >>> _______________________________________________ >>> SLIM mailing list >>> SLIM@ietf.org >>> https://www.ietf.org/mailman/listinfo/slim >>> >> >> >> -- >> Randall Gellens >> Opinions are personal; facts are suspect; I speak for myself only >> -------------- Randomly selected tag: --------------- >> Algol was a great improvement on most of its successors. >> --C.A.R Hoare >> >> _______________________________________________ >> SLIM mailing list >> SLIM@ietf.org >> https://www.ietf.org/mailman/listinfo/slim >> > > > -- > Randall Gellens > Opinions are personal; facts are suspect; I speak for myself only > -------------- Randomly selected tag: --------------- > If we do not change our direction we are likely to end up where we are > headed. >
- [Slim] Eric Rescorla's No Objection on draft-ietf… Eric Rescorla
- Re: [Slim] Eric Rescorla's No Objection on draft-… Bernard Aboba
- Re: [Slim] Eric Rescorla's No Objection on draft-… Eric Rescorla
- Re: [Slim] Eric Rescorla's No Objection on draft-… Randall Gellens
- Re: [Slim] Eric Rescorla's No Objection on draft-… Bernard Aboba
- Re: [Slim] Eric Rescorla's No Objection on draft-… Randall Gellens (IETF)
- Re: [Slim] Eric Rescorla's No Objection on draft-… Eric Rescorla
- Re: [Slim] Eric Rescorla's No Objection on draft-… Eric Rescorla
- Re: [Slim] Eric Rescorla's No Objection on draft-… Paul Kyzivat
- Re: [Slim] Eric Rescorla's No Objection on draft-… Randall Gellens
- Re: [Slim] Eric Rescorla's No Objection on draft-… Gunnar Hellström
- Re: [Slim] Eric Rescorla's No Objection on draft-… Eric Rescorla
- Re: [Slim] Eric Rescorla's No Objection on draft-… Randall Gellens
- Re: [Slim] Eric Rescorla's No Objection on draft-… Eric Rescorla
- Re: [Slim] Eric Rescorla's No Objection on draft-… Bernard Aboba
- Re: [Slim] Eric Rescorla's No Objection on draft-… Bernard Aboba
- Re: [Slim] Eric Rescorla's No Objection on draft-… Gunnar Hellström
- Re: [Slim] Eric Rescorla's No Objection on draft-… Randall Gellens
- Re: [Slim] Eric Rescorla's No Objection on draft-… Eric Rescorla
- Re: [Slim] Eric Rescorla's No Objection on draft-… Randall Gellens
- Re: [Slim] Eric Rescorla's No Objection on draft-… Randall Gellens
- Re: [Slim] Eric Rescorla's No Objection on draft-… Eric Rescorla
- Re: [Slim] Eric Rescorla's No Objection on draft-… Paul Kyzivat
- Re: [Slim] Eric Rescorla's No Objection on draft-… Gunnar Hellström
- Re: [Slim] Eric Rescorla's No Objection on draft-… Randall Gellens
- Re: [Slim] Eric Rescorla's No Objection on draft-… Randall Gellens
- Re: [Slim] Eric Rescorla's No Objection on draft-… Gunnar Hellström
- Re: [Slim] Eric Rescorla's No Objection on draft-… Gunnar Hellström
- Re: [Slim] Eric Rescorla's No Objection on draft-… Randall Gellens
- Re: [Slim] Eric Rescorla's No Objection on draft-… Gunnar Hellström
- Re: [Slim] Eric Rescorla's No Objection on draft-… Randall Gellens
- Re: [Slim] Eric Rescorla's No Objection on draft-… Paul Kyzivat
- Re: [Slim] Eric Rescorla's No Objection on draft-… Gunnar Hellström
- Re: [Slim] Eric Rescorla's No Objection on draft-… Paul Kyzivat
- Re: [Slim] Eric Rescorla's No Objection on draft-… Randall Gellens
- Re: [Slim] Eric Rescorla's No Objection on draft-… Gunnar Hellström
- Re: [Slim] Eric Rescorla's No Objection on draft-… Randall Gellens
- Re: [Slim] Eric Rescorla's No Objection on draft-… Gunnar Hellström
- [Slim] Updated version addresses comments receive… Randall Gellens
- Re: [Slim] Updated version addresses comments rec… Randall Gellens
- Re: [Slim] Updated version addresses comments rec… Randall Gellens