Rockson Li (zhengyli) wrote:
> Paul,
>
> Yes, I know NOTIFY may arrive first if 2xx is lost somewhere in the
> middle.
> However, from the RFC5057 call flow diagram, I don't see any response
> lost description there.
>
> And if NOTIFY and SUBSCRIBE response are handled asynchronously, there
> might be case NOTIFY is sent first, but SUBCRIBE is rejected with
> non-2xx final response.
Well, I guess it would be an erroneous implementation that let that
happen. It shouldn't set off the async generation of NOTIFY until it
knows the subscription is going to succeed.
> So NOTIFY here does not make any sense. I still prefer to send NOTIFY
> after sending 2xx response (even it's lost somewhere in the middle) as
> per RFC3265
I think it is fine that you prefer it. Its only a matter of whether it
is required.
I think it is also fine that the example show the preferred usage. But
it might then also be good for the example to show the 2xx and NOTIFY
being sent in preferred order but *arriving* in the other order, just to
get the attention of those implementors that implement to the examples
rather than to the specs.
Thanks,
Paul
> Thanks
>
> Regards,
> -Rockson
>
>
> -----Original Message-----
> From: Paul Kyzivat (pkyzivat)
> Sent: Tuesday, August 05, 2008 9:40 PM
> To: Rockson Li (zhengyli)
> Cc: [email protected]
> Subject: Re: [Sip-implementors] question on RFC5057 Multiple Dialog
> Usages in SIP
>
> Even if the NOTIFY is sent after the 2xx (SUBSCRIBE) it may arrive
> first. And in the case if forking it may arrive without ever receiving a
> 2xx. So the subscriber must be prepared to receive it first. Once you
> realize that, there is little point in restricting the notifier to send
> the 2xx first. I suspect in some implementations these may be handled
> asynchronously, and so the order of sending may be indeterminate. I see
> no reason to force the implementation to synchronize them.
>
> Thanks,
> Paul
>
> Rockson Li (zhengyli) wrote:
>> Hi folks,
>>
>> I think the first NOTIFY message should be sent after 2xx(SUBSCRIBE).
>> This is described in RFC3265 sec3.1.6.2
>>
>>
>> Note that a NOTIFY message is always sent immediately after any
> 200-
>> class response to a SUBSCRIBE request, regardless of whether the
>> subscription has already been authorized.
>>
>>
>> But why in RFC5057 Figure 3, both F1 and F2 are sent before
>> 200(SUBSCRIBE)?
>>
>> thanks
>>
>> -Rockson
>> _______________________________________________
>> Sip-implementors mailing list
>> [email protected]
>> https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors
>>
>
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