Looks like we are in agreement. Your paraphrasing of my
proposal is accurate.

Let's wait for other opinions. 

> -----Original Message-----
> From: Dean Willis [mailto:[EMAIL PROTECTED] 
> Sent: Thursday, October 11, 2007 12:32
> To: Audet, Francois (SC100:3055)
> Cc: Christer Holmberg; IETF SIP List
> Subject: Francois' counter to INFO (was Re: What are we 
> arguing about when we say INFO?)
> 
> 
> On Oct 11, 2007, at 11:55 AM, Francois Audet wrote:
> 
> > Hi Dean,
> >
> > Can you tell me what is the difference between 
> "contextually-adapted 
> > INFO", and a "subscription embedded in the INVITE, with the NOTIFY 
> > using the same dialog"? I don't see any advantage to the INFO 
> > approach.
> >
> 
> One might argue that the second is a means of implementing the first.
> 
> INFO, as written, lacks contextual negotiation. You're 
> proposing to replace the method name with NOTIFY and use the 
> event-package framework for content and context expression, 
> using a header-field in the INVITE request to engage context 
> negotiation. It seems to me like that would work. There's 
> nothing "implicit" about it, and it is no worse for overhead 
> than using Supported or Allow. It also has the advantage of 
> letting us reuse an existing registration framework, IANA 
> process, and specification review process under RFC 3427. 
> Very tidy, I think I like it.
> 
> I would argue that it would be nice to have an extension 
> mechanism that allows a UA to be asked "Do you support this 
> specific extension?" without the UA having to encode every 
> extension it supports in every request it sends, but that's a 
> different issue.
> 
> 
> > It seems to me we already have a mechanism for asking for 
> asynchroous 
> > information with subscriptions. Why not use that?
> >
> 
> As you pointed out, the current mechanism adds a dialog 
> overhead. It also raises issues with event-stream correlation 
> that can be a bit of a challenge depending on the 
> application's API and threading model.  
> Your suggested workaround for in-dialog notification relieves 
> these issues, so it may be better than the existing mechanism 
> for a number of use cases. More importantly, it is no worse 
> than NOTIFY for those use cases (barring the small increase 
> in request size for context negotiation).
> 
> --
> Dean
> 
> 
> 


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