Re: [sixpac] Resolving SIP/XMPP URIs

"Elwell, John" <john.elwell@siemens-enterprise.com> Wed, 02 February 2011 07:44 UTC

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From: "Elwell, John" <john.elwell@siemens-enterprise.com>
To: "Markus.Isomaki@nokia.com" <Markus.Isomaki@nokia.com>, "Simo.Veikkolainen@nokia.com" <Simo.Veikkolainen@nokia.com>, "sixpac@ietf.org" <sixpac@ietf.org>
Date: Wed, 2 Feb 2011 08:48:06 +0100
Thread-Topic: Resolving SIP/XMPP URIs
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Subject: Re: [sixpac] Resolving SIP/XMPP URIs
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I see now, this was meant to be a requirement to obtain the XMPP address WITHOUT establishing a SIP call. If a SIP call were to be established, that would be covered by REQ-2 (although expressed slightly differently there).

So the question is whether, without making a SIP call, there should be a requirement to be able to discover the XMPP address. I don't have a strong opinion, but it certainly sounds reasonable to require this - I could check your presence status or send you an IM without calling you.

Concerning the solution space, OPTIONS might indeed be one method. For example, if Call-Info were used to exchange the address during a call, it could also be exchanged in OPTIONS. There is little else, unless we have an event package, which seems unnecessarily complex.

John

> -----Original Message-----
> From: Markus.Isomaki@nokia.com [mailto:Markus.Isomaki@nokia.com] 
> Sent: 01 February 2011 12:00
> To: Elwell, John; Simo.Veikkolainen@nokia.com; sixpac@ietf.org
> Subject: Resolving SIP/XMPP URIs
> 
> Hi,
> 
> John Elwell wrote:
> >
> >5. "REQ-4:  It must be possible for a user, who only knows another
> >user's
> >           SIP URI, to learn the other user's XMPP URI."
> >Is there a particular reason this is asymmetrical? Should 
> there also be
> >a requirement for a user who knows another user's XMPP URI 
> to learn that
> >user's SIP URI?
> >
> 
> From requirements and user experience perspective this should 
> be symmetric, so I would agree adding that to the requirements.
> 
> The actual protocol realization may be more challenging. In 
> the SIXPAC "model" presence information is exchanged via 
> XMPP. So, if a SIXPAC client knows an XMPP address, it can 
> conveniently use presence to learn about the corresponding 
> SIP address (using the envisioned presence data extensions). 
> But if the SIXPAC client knows a SIP address to start with, 
> what would be preferred way for learning the corresponding 
> XMPP address? Would SIP OPTIONS be a good approach? That's 
> the only realistically deployable method that I can think of. 
> Can we assume OPTIONS would work at least to a reasonable 
> extent between SIP UAs in current SIP deployments? (On paper 
> it does, but unfortunately we always need to ask this 
> question due to the deployment realities...)
> 
> Markus
>