Re: [siprec] Ben Campbell's No Objection on draft-ietf-siprec-metadata-20: (with COMMENT)

["Ben Campbell" <[e-mail]>]

On 14 Mar 2016, at 17:45, Paul Kyzivat wrote:

> On 3/14/16 2:27 PM, Ben Campbell wrote:
>> On 9 Mar 2016, at 16:51, Paul Kyzivat wrote:
>>
>>> On 3/9/16 5:40 PM, Ben Campbell wrote:
>>>
>>>
>>>> I read that to mean that the SRS builds a database over time, and
>>>> recognizes that the same CS arrived in two different xml documents, 
>>>> and
>>>> therefore associates it with the <recording> element of each?
>>>>
>>>> If so, that seems to conflict with the statement in the 2nd to last
>>>> paragraph in section 4, that says the model represents a snapshot. 
>>>> I
>>>> think maybe an XML document represents a snapshot, but the model
>>>> represents metadata accumulated over time. This would explain some
>>>> confusion I had over things like CSRS Association.
>>>
>>>
>>> The SRC delivers a series of xml snapshots over the RS. We don't
>>> mandate what the SRS does with those. But we try to provide 
>>> sufficient
>>> information so that it *could* build up a database such as you 
>>> describe.
>>
>> Keeping a history may not be required, but there seems to be
>> relationships in the model that cannot ever occur in real life unless
>> the SRS builds a cross-snapshot picture. (E.g.,  a given CS 
>> associated
>> with more than one RS, and much anything useful with CSRS 
>> associations).
>>
>>>
>>>
>>>> In any case, I don't get a sense of how this works from the draft. 
>>>> I
>>>> think it would benefit from a section that describes the high-level
>>>> operation (unless that's already in another document, in which case 
>>>> a
>>>> reference would help.)
>>>
>>>
>>> I *thought this was evident. Maybe not.
>>
>> Maybe I missed something, but the only thing I find on the subject is
>> the penultimate paragraph in section 4, which says:
>>
>> " The model allows the capture of a snapshot of a recording's 
>> metadata
>>     at a given instant in time.  Metadata changes to reflect changes 
>> in
>>     what is being recorded.  For example, if a participant joins a
>>     conference, then the SRC sends the SRS a snapshot of metadata 
>> having
>>     that participant information (with attributes like name/AoR pair 
>> and
>>     associate-time.) "
>>
>> To me that suggests that the model only describes an instant in time.
>> One might infer otherwise from the document as a whole, but I think a
>> more explicit explanation of assumptions would be helpful for someone
>> coming newly to this work.
>
> OK, you are right. Those of us who have been working on it knew what 
> we meant, but the text doesn't reflect that. Would the following be a 
> suitable replacement for the above paragraph?
>
> "The model allows metadata describing communications sessions to be 
> communicated to the SRS as a series of snapshots, each representing 
> the state as seen by a single SRC at a particular instant in time. 
> Metadata changes from one snapshot to another reflect changes in what 
> is being recorded. For example, if a participant joins a conference, 
> then the SRC sends the SRS a snapshot of metadata having that 
> participant information (with attributes like name/AoR pair and 
> associate-time.)"

Yes, that would help. Ram proposed different text, which is also fine. 
Either would improve things.

Thanks,

Ben.