Re: [MMUSIC] "New" style for defining SDP attributes

[Thomas Stach <[e-mail]>]

Christer,


On 2018-05-19 19:19, Christer Holmberg wrote:
> Hi,
>
>> the proposal works for me.
>> However, as long a we don't have definitions for ice-lite-attribute and the other stuff, I can't >reference it and have to keep the constructions and references that I currently have.
> Not sure I follow.
>
> The definitions are in draft-ietf-mmusic-ice-sip-sdp.
I couldn't find ABNF for ice-lite-attribute, pwd-attribute, 
ice-ufrag-attribute, ...
Once it's there I'll take it.

For the time being I stick with the ABNF that current is in 
draft-ietf-mmusic-trickle-ice-sip, i.e,

          ice-lite-attribute     = %s"a" "=" ice-lite
          ice-pwd-attribute      = %s"a" "=" ice-pwd-att
          ice-ufrag-attribute    = %s"a" "=" ice-ufrag-att
          ice-pacing-attribute   = %s"a" "=" ice-pacing-att

>   Yes, we may have to change those to the "new" style,
yes

Regards
Thomas
> but that should not affect the trickle draft.
>
> Regards,
>
> Christer
>
>
>
> On 2018-05-14 20:02, Christer Holmberg wrote:
>> Hi,
>>
>>> Note that I changed the subject line here. My intent was to start a different discussion that >isn't specifically related to trickle-ice-sip.
>>> The intent instead is to discuss if we should change 4566bis to be more explicit about how >to define attributes.
>> Sure.
>>
>> But, at the same time we'd like to move trickle-ice-sip forward, and I think my suggestion below allows us to do that while any possible change to 4566bis is discussed.
>>
>> Regards,
>>
>> Christer
>>
>>
>>
>> On 5/13/18 4:47 AM, Christer Holmberg wrote:
>>> Hi,
>>>
>>> My suggestion would be to simply reference the syntax. Something like:
>>>
>>> trickle-ice-sdpfrag =   session-level-fields
>>>                                          pseudo-media-descriptions
>>> session-level-fields = bundle-group-attribute CRLF          \
>>>                                          ice-lite-attribute CRLF                      \
>>>                                          ice-pwd-attribute CRLF                     \
>>>                                          ice-ufrag-attribute CRLF                    \
>>>                                          ice-options-attribute CRLF                \
>>>                                          ice-pacing-attribute CRLF                  \
>>>                                          end-of-candidates-attribute CRLF   \
>>>                                          extension-attribute-fields
>>>
>>> The attribute fields follow the generic syntax for SDP attributes [RFCXXXX]. The list below reference the specific syntax for each attribute field.
>>>
>>> ice-lite-attribute              ; as ice-lite defined in [RFCXXXX]
>>> ice-pwd-attribute            ...
>>> ice-ufrag-attribute           ...
>>> ice-pacing-attribute         ...
>>> ice-options-attribute       ....
>>>
>>> Then we don't need to worry about "new" and "old" in this draft. We simply define the high-level syntax for the sdpfrag message body, and reference the appropriate specifications for the attributes etc.
>>>
>>> In addition, I think it would be useful to say that in order to use an extension attribute, there needs to be a specification for how that attribute is used within a sdpfrag message body. Otherwise someone could include any SDP attribute just like that.
>>>
>>> Regards,
>>>
>>> Christer
>>>
>>>
>>> -----Original Message-----
>>> From: mmusic [mailto:[e-mail]] On Behalf Of Paul
>>> Kyzivat
>>> Sent: 12 May 2018 19:41
>>> To: [e-mail]
>>> Subject: [MMUSIC] "New" style for defining SDP attributes
>>>
>>> On 5/10/18 12:59 PM, Christer Holmberg wrote:
>>>
>>>> That's a bad example since a=bundle-only doesn't have a value.
>>>>
>>>> A better example is the tls-id attribute, defined in Section 4 of
>>>> https://www.ietf.org/id/draft-ietf-mmusic-dtls-sdp-32.txt.
>>>>
>>>>
>>>> I'd rather prefer ( just personal preference ) the style of
>>>> https://tools.ietf.org/html/draft-ietf-mmusic-rid-14, where the
>>>> registration in section 11 refers to the grammar in section 10.
>>>>
>>>> The ABNF is not according to the new style.
>>>>
>>>> And, just to clarify, my comments are not based on my personal
>>>> preference, but on my understanding of how SDP attributes are to be
>>>> defined nowadays.
>>> I've been finding that the "new" style that I have been trying to get institutionalized isn't well enough specified. I'm thinking that we need to firm it up, and preferably get that written down in 4566bis.
>>>
>>> 	Thanks,
>>> 	Paul
>>>
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