RE: Communication means in draft-ietf-impp-cpim-pidf-05

Krisztian wrote on 08/30/2002 10:35:13

> I feel it's very important for the presentity to publish her 
> willingness additionally to the availability of a SIP URI. If SIP 
> should be used to negotiate the communication means, this would 
> mean that the SIP URI would always be "OPEN" whenever the 
> presentity is availably for any communication, so she would be 
> needed to reject those communication means from SIP invitations, 
> which she is not willing to accept. I rather think that presence 
> is supposed to be used to publish willingness, so the watchers 
> know beforehand what is the way to contact the presentity.

I think that Krisztian has identified a real problem with SIP URIs in the 
context of PIDF. To whit, SIP defines an interactive means of initiating 
and controlling session/s between a SIP initiator and SIP end points 
associated (registered) with a SIP AoR. It is intrinsically an interactive 
real-time protocol. The whole point of publishing presence information is 
to allow, in this context, a SIP initiator to know in advance that a 
presentity (SIP AoR) is available and with what capabilities. We can maybe 
punt for now, but I fear that we will need to revisit this issue. Sadly, 
we may need to carry SIP header and SDP body text in PIDF.

Nick





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