Re: [Sipping] cc-transfer and app-interaction: providing a context for REFER

It seems like there is general consensus for this approach. As such, I 
have gone ahead and submitted an update to the framework. Until it 
appears in the archives, you can pick up a copy at:

http://www.jdrosen.net/papers/draft-ietf-sipping-app-interaction-framework-04.txt

This includes comments made during WGLC.

This document is now ready to go to IESG.

Thanks,
Jonathan R.

Jonathan Rosenberg wrote:

> Folks,
> 
> I was about to submit an update to the app-interaction framework, when I 
> remembered that an issue came up at IETF 61 around the sipping 
> cc-transfer draft that had potential impacts on app-interaction.
> 
> The issue, as you may recall, is how to do transfer with REFER on a 
> separate dialog (routed using GRUU), and correlate that REFER to the 
> dialog it would have otherwise been sent on. GRID was at first proposed, 
> but then rejected. IIRC, this was because it require the UA to use a 
> different, unique grid for every dialog it would ever set up, and that 
> was incompatible with certain uses of grid, like creating a focus URI 
> resident on a UA.
> 
> So, how to provide this correlation?
> 
> The app-interaction framework has already seen this problem, and has a 
> solution documented there. The action item from the meeting was to make 
> sure these were in sync.
> 
> The app-interaction framework defines a "context" parameter to Refer-To 
> that includes the tags and call-id of the associated dialog. The 
> semantics are that it is solely for authorization purposes. The 
> existence of the context parameter with those values indicates that the 
> REFERer has access to the dialog identifiers for the dialog. Thus, if 
> the REFER authorization policy is based on whether it comes from someone 
> with whom I am engaged in a dialog, it can be used for authorization 
> purposes. Its semantics are no deeper than that.
> 
> I would propose that the current syntax and semantics defined in 
> app-interaction suffice for the cc-transfer case. app-interaction is 
> actually a SIP working item as it defines a new extension. Thus, 
> cc-transfer could just reference it normatively and use it.
> 
> Comments?
> 
> -Jonathan R.

-- 
Jonathan D. Rosenberg, Ph.D.                   600 Lanidex Plaza
Director, Service Provider VoIP Architecture   Parsippany, NJ 07054-2711
Cisco Systems
jdrosen@cisco.com                              FAX:   (973) 952-5050
http://www.jdrosen.net                         PHONE: (973) 952-5000
http://www.cisco.com

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