RE: [Sip] RE: Delivering request-URI and parameters to UAS via proxy

["Francois Audet" <[e-mail]>]

I think we should charge customers per URI in the protocol.

We'd be rich. 

> -----Original Message-----
> From: Elwell, John [mailto:[e-mail]] 
> Sent: Tuesday, January 15, 2008 01:20
> To: Christer Holmberg; Audet, Francois (SC100:3055)
> Cc: [e-mail]; DRAGE, Keith (Keith); Paul Kyzivat
> Subject: RE: [Sip] RE: Delivering request-URI and parameters 
> to UAS via proxy
> 
> Christer,
> 
> I guess what still confuses me is, when both Target and P-CPI 
> are used, which comes first, i.e., which represents the 
> earlier target? When I read the draft, I thought Target was 
> earlier. From various clarifying emails I now get the 
> impression that Target is later. Can you confirm?
> 
> Picking up on Francois' point about History-Info, with the 
> introduction of Target and P-CPI we do indeed have a lot of 
> URIs, and of course History-Info can already convey all these 
> URIs and any others. The difference is that History-Info does 
> not give particular semantics to each of the URIs it conveys 
> - they are simply a succession of targets.
> With Target and P-CPI we are aiming to define specific 
> semantics. I am concerned whether we will be able to define 
> these semantics tightly enough to ensure consistent 
> implementations. The more URIs we try to define, the harder 
> it will be to assign each one a clearly distinguishable 
> meaning. I hope the next draft will help.
> 
> John
> 
> > -----Original Message-----
> > From: Christer Holmberg [mailto:[e-mail]]
> > Sent: 15 January 2008 08:48
> > To: Francois Audet
> > Cc: [e-mail]; DRAGE, Keith (Keith); Paul Kyzivat; Elwell, John
> > Subject: RE: [Sip] RE: Delivering request-URI and parameters to UAS 
> > via proxy
> > 
> > 
> > Hi,
> > 
> > P-CPI could probably be useful in some cases, in addition to Loose 
> > Route/Target. And, as the draft says, P-CPI will still have 
> to be used 
> > in IMS, because there are procedures defined for it.
> > 
> > However, again, the purpose of the draft was to provide an 
> alternative 
> > to the Loose Route alternative, and that alternative is Target only.
> > 
> > I am working on an updated version of the draft to make that more 
> > clear.
> > 
> > Regards,
> > 
> > Christer
> > 
> > 
> > 
> > 
> > 
> > >Hum. I guess then P-Called-ID would then be useful with 
> Loose-route 
> > >as well (although now I'm thinking that History-Info covers it).
> > > 
> > >I think explaining all that in great and precise details, with a 
> > >concrete example would be very useful.
> > > 
> > >And then we could compare P-Target with Loose-route. 
> > 
> > 
> > 
> > 
> > 
> > > 
> > > > -----Original Message-----
> > > > From: Christer Holmberg [mailto:[e-mail]]
> > > > Sent: Monday, January 14, 2008 03:56
> > > > To: Audet, Francois (SC100:3055)
> > > > Cc: [e-mail]; DRAGE, Keith (Keith); Paul Kyzivat; 
> Elwell, John
> > > > Subject: RE: [Sip] RE: Delivering request-URI and
> > parameters to UAS
> > > > via proxy
> > > > 
> > > > 
> > > > Hi Francois,
> > > > 
> > > > >I think what you meant by Target was more the "Current" 
> > > > >target as opposed to the Initiatl Target.
> > > > 
> > > > Yes.
> > > >  
> > > > >And if that's the case, then I don't see why it is
> > different from
> > > > >P-Called-ID (although I might be missing something 
> with what the 
> > > > >P-Called_ID is supposed to be).
> > > > 
> > > > In the draft we try to explain the difference. But, we are
> > > working on
> > > > the text to make it more clear.
> > > > 
> > > > The P-CPI is inserted when the R-URI is rewritten by 
> the Contact 
> > > > address of the UAS. RFC3455 calls that operation
> > > "retargeting", but we
> > > > don't think that is the definition for retarget used in the 
> > > > ua-loose-route draft, which says:
> > > > 
> > > > "When a home proxy receives a request and accesses a
> > > location service,
> > > > the resulting contact(s) obtained from the location service are 
> > > > considered the last hop in the route towards the entity
> > > addressed by
> > > > the Request-URI.  Since that target, almost by definition,
> > > can claim
> > > > the identity of the URI prior to translation, the operation
> > > is one of
> > > > routing and not retargeting."
> > > > 
> > > > So, if we follow the definitions in the ua-loose-route
> > draft, P-CPI
> > > > would be inserted due to a reroute - not retarget.
> > > > 
> > > > But, no matter whether we call it retarget or reroute,
> > the point is
> > > > that the P-CPI is inserted when the R-URI is rewritten with the 
> > > > Contact address of the UAS. The scope of Target is wider
> > than that,
> > > > and can be used in any retargeting situation.
> > > > 
> > > > Regards,
> > > > 
> > > > Christer
> > > > 
> > > > 
> > > 
> > 
> 


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