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. 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 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 > _______________________________________________ Sip-implementors mailing list [email protected] https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors
