Re: [sipcore] New Version Notification for draft-sparks-sipcore-refer-explicit-subscription-01

[Robert Sparks <[e-mail]>]

On 10/6/14 12:44 AM, OKUMURA Shinji wrote:
> Hello Robert,
>
>> On 10/3/14 10:40 AM, OKUMURA Shinji wrote:
>>> Hi,
>>>
>>> As a general rule, REFER request may fork.
>>> But a referrer receives only one response(i.e. Refer-Events-At).
>>> Does this draft disallow a REFER request to be forked?
>> No.
>>
>> If the REFER forks, it will get responses from each branch of the fork.
>> The response from each branch will have its own information about whether
>> the REFER was accepted on that branch, including its own Refer-Events-At
>> URI.
> In accordance with the following, a successful response for REFER
> request is only one.
>
> RFC3261
> 17.1.2.1 Overview of the non-INVITE Transaction
>
>     Unlike an INVITE transaction, a non-INVITE transaction has no special
>     handling for the 2xx response.  The result is that only a single 2xx
>     response to a non-INVITE is ever delivered to a UAC.
Wow (slaps forehead) - very good catch. That's the whole reason the 
immediate NOTIFY
in SIP Events exists.

The consequences of that are going to require some time to think through.


>
>
>> With the typical use of REFER specified to date (transfer), the refer
>> will have
>> a Target-Dialog header field and will likely be accepted at only one of the
>> places it might have forked to.
>>
>> RjS
> Regards,
> Shinji