Re: [sipcore] composition or just indirection (was: location-conveyance-03 just submitted)

["Hannes Tschofenig" <[e-mail]>]

Still trying to catch up with the mail thread but a few basic observations: 

1) There is the 'entity' attribute in the <presence> element that points to the Target. 

2) There is RFC 5491 http://datatracker.ietf.org/doc/rfc5491/ that describes how different location chunks (including "compound location") are interpreted. It also describes the meaning of different location objects in a PIDF-LO. 

3) We know that we want to transmit multiple location chunks, and multiple location objects of the same Target. We do not seem to have use cases for transmitting location of >>different<< Targets in the same SIP message. 

So, this should allow us to carry one of multiple MIME bodies with PIDF-LOs in a SIP message (referring to the same Target) in a single SIP message. 

The following items are left for discussions, I believe: 

- How to encode the LbyR (in addition to the LbyV)
- Procedures for how an intermediary attaches a reference to a PIDF-LO 
- Whether there needs to be a relationship between the 'entity' attribute in the <presence> element and the From header of a SIP message.

I am less interested in the used-for-routing optimizations etc. 

Did I correctly capture the challenge? 

Ciao
Hannes