Subject: Re: [dispatch] new draft: Updates to Referred-By header

From: Salvatore Loreto <[email-masked]>
Date: Thu, 05 Nov 2009 17:05:16 +0200

Hi Dale,

sorry to be late answering this.

see my comments in line.

cheer
/Sal

Dale Worley wrote:
> On Mon, 2009-10-12 at 16:49 +0300, Salvatore Loreto wrote:
>   
>> Abstract
>>
>>    SIP Referred-By header field conveys the referrer identity of a
>>    request.  This header field may be used when exploding a SIP MESSAGE
>>    or a SIP INVITE request to a pre-defined group URI and the
>>    P-Asserted-Identity header field or From header field in the exploded
>>    SIP requests needs to carry another value (e.g. the URI of a pre-
>>    defined group, or a conference focus URI).  In those cases, the
>>    Referred-By header field in the resulting exploded requests is set to
>>    the P-Asserted-Identity or to the From header field value of the
>>    original SIP request received before exploding, so as to convey to
>>    the receiver the identity of the original inviting sender.
>>     
>
> What do you do if the original INVITE already has a Referred-By header?
>   
[Sal] this seems to me a general problem of any exploder procedure.
My guess is that you would replace it with the new value!
> It seems to me that you want a new header to carry this information, as
> it has distinct semantics from all existing headers.
>   
[Sal] It is not what we want!
> I am also curious why the From header of the exploded messages would
> need to be different from the From header of the original message.
>   
[Sal]
Yes it is true that RFC5365 says that the exploder MUST include the same
 From header field value as the incoming request but RFC5365 does not
take into consideration exploding when using a pre-defined group. There
needs to be a way for the message recipients to know the name of the 
pre-defined group.

For SIP INVITE the From header contains the URI for the conference (see 
RFC5366),
so the original sender goes in the Referred-By.

In order to keep things a similar as possible between SIP INVITE and SIP
MESSAGE, it makes sense to put the original sender in the Referred-By
when SIP MESSAGE From has to carry a pre-defined group instead of the 
original sender.
> Dale