Subject: Re: [Sipping] CPCP and SIP {conferencing}

From: Jonathan Rosenberg <[email-masked]>
Date: Wed, 30 Apr 2003 23:32:08 -0400

Sorry for not responding to these questions earlier. Some answers inline:

Arjun Roychowdhury wrote:
> Reading 
> http://www.ietf.org/internet-drafts/draft-levin-sipping-conferencing-requirements-03.txt
>  and 
> http://www.ietf.org/internet-drafts/draft-koskelainen-sipping-conf-policy-req-00.txt
>  in conjunction,
> 
> it seems both CPCP and SIP have similar requirements and the reqts
> listed in the above two drafts to a great extent can mix with each
> other. This probably is a good  thing since that means SIP can meet
> many of CPCP's requirements.
> 
> But it does not clarify my confusion below:
> 
> In addition, framework-01, for each scenario lists a SIP way and a
> CPCP wa
> 
> Even though SIP may finally land up doing a lot of what is required
> by CPCP,  looking at the framework-01 diagram Figure 2, the interface
> between Participant and Focus is different from the interface between
> Participant and Conference Policy server.
> 
> However, when I read petri's, jonathan's and orit's drafts in
> conjunction, I see these two interfaces sparring in the same ring.
> 
> I am somewhat confused. Where does the design team consider CPCP to
> stop (Participant - CPS) and SIP dialog to start (Participant to
> Focus) ?

Firstly, we arent defining these protocols based on the fact that they 
go from element A to element B. We define them based on their functional 
properties.

In my mind, the difference between SIP and CPCP is clear. SIP is about 
initiating and managing sessions. CPCP is an RPC type of protocol that 
manipulates policies on a server. The confusion is arising because 
somtimes the establishment of a policy results in the creation of a 
session, or vice-a-versa, so that the establishment of a session is 
effectively creating some kind of change in policy.

 From the full scope of CPCP, though, its clear that it is doing many 
things that make no sense for SIP. For example, setting up policy about 
who is allowed to moderate, or setting policy about who can and can't 
join the conference. These things are clearly not SIP.

Thanks,
Jonathan R.

-- 
Jonathan D. Rosenberg, Ph.D.                600 Lanidex Plaza
Chief Scientist                             Parsippany, NJ 07054-2711
dynamicsoft
[email-masked]                     FAX:   (973) 952-5050
http://www.jdrosen.net                      PHONE: (973) 952-5000
http://www.dynamicsoft.com

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