Re: [Slim] Collapse attribute syntax to one line in draft-ietf-slim-negotiating-human-language

[Gunnar Hellström <[e-mail]>]

Den 2017-06-01 kl. 19:17, skrev Randall Gellens:
> The group has repeatedly discussed q-values and priority and has 
> always decided to not go down that path.
I expect our shepherd to lead us to the decision. We had one reviewer 
requesting us to use the Accept-Language syntax with the q-values.

I can accept either way, either the one-line syntax used in version -10, 
or the Accept-Language syntax.

If we go with the current one-line syntax, I will propose to add the 
preference between modalities by giving the asterisk a preference 
interpretation on media level.
And I will propose to use the -t language subtag for simultaneous 
languages in other modalities.
This may lack some flexibility but will likely be sufficient.

If we go with the Accept-Language syntax, then I will propose to let the 
q-values have scope over the whole SDP in order to assign preference 
between modalities,
and I will propose to let equal q-values or q-values within a narrow 
interval to indicate a preference for using simultaneous languages in 
different media.  The first item is nice and flexible, the second, for 
simultaneity may be less elegant.

I hope you will accept either solution. And do it already in the current 
draft.

So we just need the decision on the Accept-Language syntax proposal and 
then move on.

Regards

Gunnar






>
> At 4:33 PM +0200 6/1/17, Gunnar Hellström wrote:
>
>>  Den 2017-06-01 kl. 11:54, skrev Natasha Rooney:
>>
>>>  This seems sufficient given our previous conversations. q-values 
>>> can be applied within further work (although I don't see why 
>>> ordering doesn't do the job, works in web).
>>>
>>  It is not feasible to change syntax by adding q-values in an 
>> extension. That will cause interop problems, or complicated needs to 
>> negotiate protocol version. So, we need to decide the syntax now and 
>> stick closely to it.
>>
>>  Ordering is not sufficient because we have a need to set preferences 
>> between different media.
>>  Ordering only works within a media.
>>
>>  And, a minor drawback: ordering does not allow to specify a number 
>> of languages in the same media with the same preference. One always 
>> will look as if it is more preferred than another. - but I think we 
>> can live with that.
>>
>>  Maybe the main question is: Will our own one-line syntax really be 
>> less complex to parse than the Accept-Language syntax that we might 
>> be able to find ready library routines for?
>>  Adam Roach had views on complexity to parse different solutions. 
>> Maybe you, Adam can have a view on this?
>>
>>  Regards
>>
>>  Gunnar
>>
>>>
>>>  Bernard - any further thoughts?
>>>
>>>
>>>  Natasha Rooney | Internet Engineering Director | Internet and Web 
>>> Team | Technology | GSMA | <mailto:[e-mail]>[e-mail] 
>>> | [phone] | @thisNatasha | Skype: 
>>> <mailto:[e-mail]>[e-mail]
>>>
>>>>  On 30 May 2017, at 00:04, Randall Gellens 
>>>> <<mailto:[e-mail]>[e-mail]> wrote:
>>>>
>>>>  I uploaded version -10, which includes the syntax change to single 
>>>> line, along with a few editorial clarifications. (Version -09 
>>>> accidently omitted an editorial clarification.)
>>>>
>>>>  You can see a diff of the changes from 08 to 10 here:
>>>>
>>>> <https://www.ietf.org/rfcdiff?url1=draft-ietf-slim-negotiating-human-language-08&url2=draft-ietf-slim-negotiating-human-language-10>https://www.ietf.org/rfcdiff?url1=draft-ietf-slim-negotiating-human-language-08&url2=draft-ietf-slim-negotiating-human-language-10 
>>>>
>>>>
>>>>  If there objections to the change from multi-line to single-line, 
>>>> this can be reverted.
>>>>
>>>>  --Randy
>>>>
>>>>
>>>>
>>>>  At 2:57 PM -0700 5/28/17, Randall Gellens wrote:
>>>>
>>>>>  In response to Adam Roach's comments as well as other comments, I 
>>>>> intend to update the draft to collapse the attribute syntax to one 
>>>>> line; each attribute can occur at most once per media, with all 
>>>>> languages on the same line. This will further reduce the size of 
>>>>> the SDP block.
>>>>>
>>>>>  If you object to this, please reply.
>>>>>
>>>>>  Here is the section of Adam's review:
>>>>>
>>>>>  At 8:31 PM +0000 3/28/17, Sabrina Tanamal via RT wrote:
>>>>>
>>>>>>  I'll note that much of this can be fixed if the syntax is 
>>>>>> collapsed so
>>>>>>  that each media section can have at most one hlang-send and one
>>>>>>  hlang-receive, each of which contain a list of one or more 
>>>>>> languages
>>>>>>  that can be sent or received. This is also much more consistent 
>>>>>> with the
>>>>>>  way SDP attributes are used in general. The presence of a "*" 
>>>>>> token on
>>>>>>  that line would indicate the "call should happen even without 
>>>>>> matching
>>>>>>  languages" characteristic; since there is only one place to add 
>>>>>> this
>>>>>>  indicator, the ambiguity of some lines indicating it and others not
>>>>>>  disappears. The preceding example would collapse to:
>>>>>>
>>>>>>  m=audio 49250 RTP/AVP 20
>>>>>>  a=hlang-send:es eu en *
>>>>>>  a=hlang-recv:es eu en *
>>>>>>
>>>>>>  ...and the example text would be revised to remove the 
>>>>>> implication that
>>>>>>  *sending* "es" necessarily implies *receiving* "es".
>>>>>>
>>>>>>  I'll further note that the majority of SDP libraries I've worked 
>>>>>> with
>>>>>>  would make accessing the all-on-one-line format easier than
>>>>>>  one-line-per-language as well.
>>>>>>
>>>>>
>>>>>  Here is the proposed ABNF:
>>>>>
>>>>>  Attribute Syntax:
>>>>>
>>>>>  hlang-value = Language-Tag *( SP Language-tag ) [ SP asterisk ]
>>>>>
>>>>>  ; Language-Tag as defined in BCP 47
>>>>>
>>>>>  asterisk = "*" ; an asterisk (ASCII %2A) character
>>>>>
>>>>>  sp = 1*" " ; one or more ASCII space (%20) characters
>>>>>
>>>>>  --
>>>>>  Randall Gellens
>>>>>  Opinions are personal; facts are suspect; I speak for myself only
>>>>>  -------------- Randomly selected tag: ---------------
>>>>>  If forced to travel on an airplane, try and get in the cabin with
>>>>>  the Captain, so you can keep an eye on him and nudge him if he
>>>>>  falls asleep or point out any mountains looming up ahead ...
>>>>>  --Mike Harding, The Armchair Anarchist's Almanac.
>>>>>
>>>>>  _______________________________________________
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>>>>>
>>>>>
>>>>
>>>>
>>>>  --
>>>>  Randall Gellens
>>>>  Opinions are personal; facts are suspect; I speak for myself only
>>>>  -------------- Randomly selected tag: ---------------
>>>>  Knowledge always desires increase; it is like fire, which must
>>>>  first be kindled by some external agent, but which will afterwards
>>>>  propagate itself. --Dr. Samuel Johnson
>>>>
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>>
>>  --
>>  -----------------------------------------
>>  Gunnar Hellström
>>  Omnitor
>>  <mailto:[e-mail]>[e-mail]
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>
>

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Gunnar Hellström
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