Subject: RE: [Fwd: Re: [Simple] Implicit MESSAGE sessions revisited]

From: "Roy, Radhika R, ALCTA" <[email-masked]>
Date: Mon, 17 Sep 2001 14:08:34 -0400

[PK]  So, you don't you don't see the advantage of using INVITE to set up an
IM 'session' (indicating this in the SDP)? Why not? Without this, you lose
the ability to: 
- associate the IM session with other related media sessions that should be
used together; 
- transfer the IM session to another endpoint while retaining its identity
as a session; 
- transfer a grouping of media sessions as a unit if IM is involved. 

I agree that the ability to do this is independent of how the session
content is transported. It is certainly *possible* to introduce a session
via SDP, but have that session multiplexed on a common transport by the
application level. I believe there are a number of problems with that, but
it is certainly an appropriate subject for discussion. 

But first it is important to agree that it must be possible to negotiate
these sessions by the exchange of SDP. I know there are people other than
myself who believe this is essential. I don't have a good sense of how many
disagree. This is an essential point to resolve. 

[Roy, Radhika R, ALARC]  I agree with Paul that SDP is a tool in SIP that
helps to meet a variety of requirements including the above. In addition, a
stream of messages as a part of the MESSAGE session, as Dean mentioned in
his earlier message, can also  be satisfied using SDP. So, the suggestion
is: Let us write all requirements of a message session that needs to be
performed and, examine each requirement why it cannot be performed using
SDP. At that point, we can examine the detail proposal(s), if any, of the
MESSAGE session alternative to the SDP solution. 

Radhika R. Roy 

[email-masked] <mailto:[email-masked]>

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From: Robert Sparks <[email-masked]>
Date: Mon, 17 Sep 2001 14:32:41 -0400

If you've not yet reviewed draft-ietf-simple-presence-02, please do so
before returning to this thread.
 
RjS