Subject: [Simple] Single routable address in MSRP chat rooms

From: "Geir Arne Sandbakken" <[email-masked]>
Date: Sun, 6 Jan 2008 11:12:38 +0100

Being a lazy programmer I am concerned about later part of the following
sentence in the current chat draft:

"In this case the sender creates an MSRP SEND request with a
Message/CPIM body whose To or Cc headers contain not the chat room URI
but one or more nickname URIs or participant URIs."

If I want to send a private message to a user of the conference, which
URI should I choose? Should I chose the nickname URI or the participant
URI for the MSRP SEND request?  What are the criteria for selecting
either? What do I do if a nickname URI corresponds to a participant URI
for another user?

IMHO, the lazy programer would just stick with one.  All users of the
conference must have a participant URI which is a SIP URI.  It is
required to be unique, routable inside the conference and could be
routable outside the conference.  It can be used to send a private
message in a conference using MSRP SEND using the MSRP switch, or out of
conference for any SIP request.

If a user wants a specific AOR to be presented to the others as the
participant URI, we should just let the user do that.

Geir Arne

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From: "Hisham Khartabil" <[email-masked]>
Date: Mon, 7 Jan 2008 15:52:08 +1100

I think we need both. I want to be anonymous with my SIP URI and
prefer you to send me a private message (via the chatroom focus) using
my nickname. Those nicknames don't need to be routable outside the
chatroom focus.

Hisham

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From: "Geir Arne Sandbakken" <[email-masked]>
Date: Mon, 7 Jan 2008 10:08:38 +0100

Hisham,

Comments inline.

> -----Original Message-----
> From: Hisham Khartabil [mailto:[email-masked]]
> 

The anonymous SIP URI of a conference is required to be unique.  Why do
we need another unique SIP URI to route the messages distributed by the
MSRP switch? How do I choose which URI to use? 

If I want to start a private sidebar audio session with another
participant, I would use the participant URI.  Why is private chat
message any different?

Thanks,
Geir Arne

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From: "Hisham Khartabil" <[email-masked]>
Date: Tue, 8 Jan 2008 09:17:32 +1100

On 07/01/2008, Geir Arne Sandbakken <[email-masked]> wrote:
> The anonymous SIP URI of a conference is required to be unique.

No it doesn't need to be unique. Anonymous means you cannot reach me
if you use this SIP URI.

Hisham

>  Why do

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From: "Geir Arne Sandbakken" <[email-masked]>
Date: Tue, 8 Jan 2008 12:05:22 +0100

> > > [snip snip]

The conference package states that the focus has to construct the user
part of anonymous entity URI to be unique among all participants of the
same domain.  If it can't be used as a routable address inside the scope
of the conference, we need to construct one for reasons described below.

A requirement for a nickname is that it can be changed by a participant
at any time during a conference.  Having a routable address just change
will lead to race conditions and other problems.  This is especially
important for protocols like MSRP where you can chunk large messages
like files. You could try to mend the problem by adding some hefty
semantics to the focus and/or MSRP switch, but that just makes my head
spin.

We need a single routable address associated to a participant as long as
the participant is part of the conference. 

Thanks,
Geir Arne

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From: Paul Kyzivat <[email-masked]>
Date: Tue, 08 Jan 2008 11:55:34 -0500

Comment at end.

> the participant is part of the conference. 

Its my impression that one reason for changing nicknames is to appear to 
others as a different person, not correlated to the prior one. Of the 
routable address remains the same then it provides a means of correlation.

	Thanks,
	Paul

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From: "Geir Arne Sandbakken" <[email-masked]>
Date: Tue, 8 Jan 2008 23:15:53 +0100

Comments at end.

> From: Paul Kyzivat [mailto:[email-masked]]
> Sent: 08 January 2008 17:56
> To: Geir Arne Sandbakken
> Cc: Hisham Khartabil; [email-masked]
> Subject: Re: [Simple] Single routable address in MSRP chat rooms
> 
> Comment at end.
> 

I remember to have seen notifications in IRC when someone in the room
changes their nickname.  XMPP supports such notifications, but I don't
know if they are typical.  Having a teenager in the house I have seen
quite some long and wired nicknames used in various IM systems, but
their identity/address seems to be quite persistent.  It also seems like
the nicknames changes as the mood changes - which are quite often.

Do we need to support stealth changes of nicknames?

Thanks,
Geir Arne

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From: Paul Kyzivat <[email-masked]>
Date: Tue, 08 Jan 2008 19:00:11 -0500

I'm a poor judge of what we need to support here. It sounds like there 
are nickname changes that don't expect anonymity, and some that do.

	Paul

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From: "Geir Arne Sandbakken" <[email-masked]>
Date: Wed, 9 Jan 2008 10:53:28 +0100

> are nickname changes that don't expect anonymity, and some that do.

I agree, but there is a catch.  If you want to suddenly appear as
another person by changing the nickname, the change event itself also
provides means of correlation.  IMHO, the participants of a chat room
would easily detect such a change based on things like timing.

A "stealthy" nickname change would probably require that the participant
leaves the conference, wait a random amount of time and rejoin having
another routable address and another nickname.  

Thanks,
Geir Arne

> >>>>>> prefer you to send me a private message (via the chatroom
focus)
> >>> using
> >>> part of anonymous entity URI to be unique among all participants
of
> > the
> >> Its my impression that one reason for changing nicknames is to
appear
> > to

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From: Paul Kyzivat <[email-masked]>
Date: Wed, 09 Jan 2008 09:15:52 -0500

good point.

	Paul