[sixpac] Resolving SIP/XMPP URIs

[<[e-mail]>]

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