Subject: [Simple] MSRP chat: draft-niemi-simple-chat-04.txt

From: Miguel Garcia <[email-masked]>
Date: Mon, 13 Feb 2006 13:48:33 +0200

We have just submitted a new version of the MSRP CHAT draft. This has 
changed substantially from earlier versions, so I wouldn't dare to 
summarize the changes.

Until the document is published, you can fetch a copy from:
http://people.nokia.net/~miguel/drafts/draft-niemi-simple-chat-04.txt
http://people.nokia.net/~miguel/drafts/draft-niemi-simple-chat-04.html

Comments are welcome.

BR,

         Miguel

-- 
Miguel A. Garcia           tel:+358-50-4804586
sip:[email-masked]
Nokia Research Center      Helsinki, Finland

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From: Paul Kyzivat <[email-masked]>
Date: Tue, 14 Feb 2006 22:24:11 -0500

This is a great improvement. My remaining comments are primarily about 
nicknames:

- as you already comment, I think nicknames belong as a feature of 
conferences in general, not MSRP mixer sessions. In principle, I think 
the assignment of nicknames should be handled via the conference control 
protocol. (Whose accronym I currently forget.) As a result I am troubled 
by using MSRP as a protocol for doing this. (Should we also extend RTP 
to support assigning of nicknames?) The implications of doing this then 
cascade down to having new SDP to negotiate whether the MSRP peer is 
capable of assigning nicknames.

- (minor editorial issue) I think you intend to permit other mechanisms 
to deal with nickname retention. There is some language to that effect. 
But there is also language that brings this into doubt:

    In other words, a nickname is simply a username that is scoped for a
    particular chat room.  Such nicknames are allocated on a first-come
    first-served policy, meaning they can also be "stolen".  It is out of
    the scope of this specification to define nickname retention schemes,
    or nickaming services as discussed above.

This seems too strong about what a nickname *is*. I think it would be 
good to say that the server *may* issue nicknames scoped this way. But 
the user should be able to suggest any nickname that it believes the 
server may allow it to use, and the server may accept it. This would 
give much more latitude for future work.

- The lifetime of the nickname is said to be the lifetime of the 
session. But it isn't clear if that is the MSRP session or the SIP 
session. (IMO it ought to be the SIP session.) One might retain the sip 
session and change the MSRP session. This really highlights whether the 
nickname is chat specific.

That's all.

	Paul

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From: Miguel Garcia <[email-masked]>
Date: Wed, 15 Feb 2006 16:24:21 +0200

Paul:

Inline comments:

> capable of assigning nicknames.

The current idea is that nicknames are especially useful when you use 
them for providing privacy, but still be able to send "a communication" 
to the other party via the conference server. This is easy to fulfill 
with any Instant Messaging protocol, because if I the conference server 
anonymizes me, I can still send you an IM and you can reply back to me 
through my nickname, but you don't know my real SIP URI.

I don't really know what is the use case for RTP, because if I send you 
audio or video you will identify me immediately, in spite the conference 
server is anonymizing me.

So that has been the main driver for providing the function in MSRP. The 
other thing is that, existing systems (and IRC is an example of it) 
provide similar functionality.

Yet another thing... I am not sure what will be the reaction of the SIP 
WG if we propose the standardization of the NICKNAME method...

> give much more latitude for future work.

OK, sounds a nice suggestion.

> nickname is chat specific.

This is a good point since, I always got in mind that the SIP session 
has an MSRP session... but I see the difference, so obviously that has 
to be clarified. And I see the point that this should be tied to the SIP 
session...

Thanks,

      Miguel

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From: Paul Kyzivat <[email-masked]>
Date: Wed, 15 Feb 2006 11:50:58 -0500

more comments inline.

	Paul

Miguel Garcia wrote:
>> the assignment of nicknames should be handled via the conference 
>> control protocol. (Whose accronym I currently forget.) As a result I 
>> am troubled by using MSRP as a protocol for doing this. (Should we 
>> also extend RTP to support assigning of nicknames?) The implications 
>> of doing this then cascade down to having new SDP to negotiate whether 
>> the MSRP peer is capable of assigning nicknames.
> 
> 

The example of RTP was intended as a bit of a joke, but not entirely.

My thinking is that these nicknames can be learned via the roster from 
the focus, independent of the particular media being used in the call. 
Once I know the identity of a particular participant, then the desire to 
target communications to that person can also be independent of the 
particular media.

Also, the fact that my voice is recognizable does not eliminate the 
value of a nickname for voice. In most of the cases I am aware of, the 
participants most likely don't know one another outside the chat room 
and so would not be able to correlate the voice with a real identity.

I don't seriously think that it would make sense to request a nickname 
via RTP. MSRP is somewhat more ammenable to doing that, but it doesn't 
seem any more appropriate. Getting the nickname from the focus makes 
more sense to me. That still requires some mechanism, for each medium, 
to indicate that the media should be sent to a particular set of 
nicknames. The most general mechanism for that is the sidebar, but I 
know you consider that too heavyweight for some purposes. Perhaps it is 
ok that some media have a way other than sidebars, but for others the 
sidebar is the only mechanism.

> WG if we propose the standardization of the NICKNAME method...

I don't think it belongs in SIP. I had CSCP in mind as a suitable place.

	Paul

>> - (minor editorial issue) I think you intend to permit other 
>> mechanisms to deal with nickname retention. There is some language to 
>> that effect. But there is also language that brings this into doubt:
>>
>> session. (IMO it ought to be the SIP session.) One might retain the 
>> sip session and change the MSRP session. This really highlights 
>> whether the nickname is chat specific.
>>
>