Re: [Slim] Last Call: <draft-ietf-slim-negotiating-human-language-06.txt> (Issue 5, section 5.3 )

[Gunnar Hellström <[e-mail]>]

Den 2017-02-14 kl. 00:44, skrev Paul Kyzivat:

> On 2/13/17 12:53 PM, Doug Ewell wrote:
>
>> Gunnar, who participated extensively in the SLIM WG, appears to be
>> attempting to re-introduce a mechanism to indicate preference of
>> modality which was considered and rejected multiple times by the WG.
>>
>> WG rejection of Gunnar's previous proposals to do this was based on
>> reluctance to try to solve this particular problem in the first version
>> of the spec, not on any of the specific mechanisms proposed to solve the
>> problem. Proposing a new or modified mechanism during IETF LC appears to
>> be an attempt to rehash an argument made, but not won, in the WG.
>>
>> If this concerns a different issue, not merely a different way of
>> approaching it, please accept my apology and explain more clearly how it
>> is different.
You are partly right, but the new proposal concerns more issues and is 
suggested to be a simplified solution to them.

The proposal adds media level influence to the asterisk humintlang 
attribute value parameter. In draft -06 the asterisk is said to be a 
media level parameter. But it does not change any influence on media 
level depending on which media or humintlang attribute you append it to. 
It just has session influence. That clearly indicates that with the 
current definition, the asterisk parameter  is misplaced.

It can also be seen that it has quite vague and unprecise influence on 
the session level.

This is the essential part of section 5.3 where this parameter is defined:

"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."

So, the lack of the parameter everywhere in the SDP MAY be seen as a 
request to reject the call, but that request may be ignored.

The real effect of this parameter is therefore in fact a preference. In 
order to motivate its existence on the media level, I proposed the 
extension of its meaning with an influence depending on on which 
humintlang attribute(s) it is attached.
Since the lack of the parameter apparently indicates a stronger 
preference for getting the call through, I suggest that the placement of 
an asterisk on a specific humintlang attribute indicates lower 
preference for matching that language/modality/direction versus some 
other language/modality combination specified for the same direction.
The one who want the call rejected if the highest preferred 
language/modality could not be matched is likely less interested in 
providing lower preferenced alternatives, so the session influence can 
be maintained.

By that we both sort out inconsistencies with the use of the asterisk 
and add value to it that will enable much more satisfied users and more 
calls going through.
And the solution is simpler than all earlier proposals and much more 
simple than not acting on the addressed issues now.

My proposed wording is available in issue 5 in my initial mail from Feb 13.


  Regards
Gunnar

>
> Gunnar's comment makes multiple points. You have highlighted one of 
> them and ignored the others.
>
> Even if you reject that one, consider the others. Notably:
>
> - The text needs to be improved simply to properly explain and define 
> the syntax related to the "*" as you intend to use it.
>
> - the use of the "*" to indicate what it does is confusing. It is 
> using a media level attribute "parameter" to signify a session level 
> property. This has been brought up before, but simply rejected without 
> (IMO) adequate justification. There seems to be some love for this 
> particular syntax. ISTM that in part Gunnar is trying to adapt this 
> syntax so that it both makes sense as a media-level attribute and 
> simultaneously can satisfy the session level need that has been 
> identified.
>
> I accept the WG's decision not to address the "preference" issue. But 
> this attachment to the "ugly child", if not addressed, invites getting 
> IESG LC comments.
>
>     Thanks,
>     Paul
>
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Gunnar Hellström
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