Re: [martini] New text for gin section 7.1.1 first paragraph

[Brian Lindsay <[e-mail]>]

Hi Hadriel,

   My preference, rather than having a MUST with an unless clause, is to not use MUST in the 1st place. I think your comments below reflect the fact that the unless clause is really something that should be out of scope of the draft - and that there should not be a need for an associated MUST on requirements for GRUU. 

   Thanks
      Brian


-----Original Message-----
From: Hadriel Kaplan [mailto:[e-mail]] 
Sent: Wednesday, September 29, 2010 1:33 PM
To: Brian Lindsay
Cc: Paul Kyzivat; Elwell, John; [e-mail]
Subject: Re: [martini] New text for gin section 7.1.1 first paragraph


But it doesn't mandate GRUU be used with GIN.  John's proposed text is:
"An SSP needs to provide a means of assigning a globally routable contact URI to a UA behind a SIP-PBX, thereby allowing other entities to address out-of-dialog requests to that UA. To achieve this, an SSP MUST support the public GRUU mechanism described in this section, unless the SSP has other means of providing globally routable contact URIs (e.g., by acting as a B2BUA and performing mapping between SIP-PBX-provided local contact URIs and SSP-provided globally routable contact URIs)."

The "unless..." exemption means you don't have to do GRUU, which means the REGISTER response does not have to provide one, which means the PBX can't expect there to be one in it.  So the registration succeeds, sans GRUU.  At that point an SSP can do whatever it likes, since the rest of the "unless..." statement is unenforceable and undetectable on-the-wire.  You'd only "detect" it's not complied with if a particular service like transfer doesn't work in some scenario; and whether to support that scenario is a decision between the SSP and its Enterprise customer at that point.  It's really just hubris on the IETF's part, but who cares?

-hadriel

On Sep 29, 2010, at 12:52 PM, Brian Lindsay wrote:

>  GIN has defined a how GRUU's can be used with the GIN mechanism, but I don't think it's necessary to mandate when they are used. It's technically possible to use the basic GIN registration mechanism independent of GRUU, so I think the coupling isn't necessary.
> 
> 
> Thanks,
> Brian