I just tried to catch up on the discussion here. I mostly see circularargument/counterargument with no changing of position. The only thing I have seen here that seems new is Gonzalo's proposalabout "media in use". I see a lot of issues raised about UAs using media they are not beingcharged for. As Tom Taylor said, this is not a new argument, or uniqueto this situation. There is always the possibility that two UAs willattempt to communicate using media they did not signal in an obvious wayin the signaling channel. If they succeed in doing so, it is presumablybecause they are using a media path that they have access to independentof the signaling. In that case the intermediary who feels it should becharging for this is simply hoping to charge for a service it is notproviding, and so has no real grievance. The case where this might be a real problem is if a middlebox controlsthe media path (what resources are assigned, and whether media is /isn't permitted to flow), and yet the rules about session state are suchthat the middlebox and the endpoints have differing understandings ofwhether the active session includes a given media path or not. IMO thatis the key issue that needs to be nailed down. Thanks, Paul gaoyang wrote:> > New drawbacks:> > 1. In the original mail, "in use" is after O/A and can be used.> In RFC3261,> If the session description has changed, the UAS> MUST adjust the session parameters accordingly, possibly *after asking> the user for confirmation*.> "*asking the user for confirmation*" can be user's preference(as Local > Policy).> > Then, the "in use" can be depend on "Local Policy".> > 2. As your original example:> some with precondition not OK, some without precondition or precondition > has been OK.> The modification part of the later(without precondition or precondition > has been OK) can need for "*asking the user for confirmation*".> > But the Re-INVITE failed for precondition not satisfied, and the user > will not be alerted or hinted. But the modification would go on beyond > user's idea.> > Another "Let alone" drawback, it is more serious than "rejected but > still let alone".> For "rejected but still let alone", user at least know what happened.> > 3. Partially comit and partially rollback of O/A which is considered atomic.> The impact is unknown now.> > > > > > Date: Fri, 27 Feb 2009 12:38:14 +0200> > From: Gonzalo.Camarillo@xxxxxxxxxxxx> > To: gao.yang2@xxxxxxxxxx> > CC: sipping-bounces@xxxxxxxx; sipping@xxxxxxxx; > christer.holmberg@xxxxxxxxxxxx> > Subject: Re: 答复: Re: 答复: Re: 答复: Re: ??: Re: ??: Re: > ??: Re: ??: Re: ??: Re: ??: Re: ??: Re: Closing the offer/answer > rollback issue> >> > Hi,> >> > at this point, the discussions are going in circles and are not> > productive any longer. No new ideas are being introduced.> >> > I think I now understand your main points (media synchronization and> > session continuity) so that I can put together a more formal description> > of the straw-man proposal in my original email that meets all the> > requirements brought up here.> >> > The proposal will be what the WG had agreed on before with slight> > modifications (e.g., a clarification of the "in use" concept) in order> > to better address your concerns.> >> > Thanks for your input,> >> > Gonzalo> >> > gao.yang2@xxxxxxxxxx wrote:> > >> > > Yes. I think it is can, not MUST.> > >> > > And with precondition, the user can be hinted the new modification > just> > > after Offer/Answer pairs.> > >> > >> > >> > >> > > *Gonzalo Camarillo <Gonzalo.Camarillo@xxxxxxxxxxxx>*> > >> > > 2009-02-27 18:22> > >> > >> > > 收件人> > > wang.libo@xxxxxxxxxx> > > 抄送> > > christer.holmberg@xxxxxxxxxxxx, gao.yang2@xxxxxxxxxx, > sipping@xxxxxxxx,> > > sipping-bounces@xxxxxxxx, Eric.wangxr@xxxxxxxxx> > > 主题> > > Re: 答复: Re: 答复: Re: ??: Re: [Sipping] ??: Re: ??: Re: ??: Re: ??:> > > Re: ??: Re: ??: Re: Closing the offer/answer rollback issue> > >> > >> > >> & gt; >> > >> > >> > >> > >> > > Hi,> > >> > > UEB would have rejected the video stream in the 183 response.> > >> > > Gonzalo> > >> > > wang.libo@xxxxxxxxxx wrote:> > > >> > > > HI,> > > >> > > > I think the video will be established.The figure below shows the > case.> > > >> > > >> > > > 1. REINVITE(audio，vedio)> > > > ----------------------------->> > > > 2. 183> > > > <-----------------------------> > > > 3. PRACK/200> > > > <------------------------------>> > > > 4. UPDATE(audio，vedio)> > > > ----------------------------->> > > > 5. 200(audio，vedio)> > > > <-----------------------------> > > >> > > > 6. 4XX> > > > <-----------------------------> > > >> > > > After step 5, UEs' precondition are met ,and the video stream is> > > > established too.> > > > But UE-B send 4xx to reject 4XX (step 6).> > > >> > > > Regards.> > > >> > > >> > > >> > > >> > > > *Gonzalo Camarillo <Gonzalo.Camarillo@xxxxxxxxxxxx>*> > > >> > > > 2009-02-27 17:30> > > >> > > >> > > > 收件人> > > > wang.libo@xxxxxxxxxx> > > > 抄送> > > > christer.holmberg@xxxxxxxxxxxx,> > > gao.yang2@xxxxxxxxxx, sipping@xxxxxxxx,> > > > sipping-bounces@xxxxxxxx> > > > 主题> > > > Re: 答复: Re: ??: Re: [Sipping] ??: Re: ??: Re: ??:> > > Re: ??: Re: ??:> > > > Re: ??: Re: Closing the offer/answer rollback issue> > > >> > > >> > > >> > > >> > > ; >> > > >> > > >> > > >> > > > Hi,> > > >> > > > > If UE-A wants to communicate with UE-B by video, but UE-B only> > > want to> > > > > communicate by audio.> > > >> > > > then UE-B rejects the video stream and the video stream is never> > > > established.> > > >> > > > Cheers,> > > >> > > > Gonzalo> > > >> > > >> > > > --------------------------------------------------------> > > > ZTE Information Security Notice: The information contained in this> > > mail is solely property of the sender's organization. This mail> > > communication is confidential. Recipients named above are obligated to> > > maintain secrecy and are not permitted to disclose the contents of > this> > > communication to others.> > > > This email an d any files transmitted with it are confidential and> > > intended solely for the use of the individual or entity to whom > they are> > > addressed. If you have received this email in error please notify the> > > originator of the message. Any views expressed in this message are > those> > > of the individual sender.> > > > This message has been scanned for viruses and Spam by ZTE Anti-Spam> > > system.> > >> > >> > >> > > --------------------------------------------------------> > > ZTE Information Security Notice: The information contained in this > mail is solely property of the sender's organization. This mail > communication is confidential. Recipients named above are obligated to > maintain secrecy and are not permitted to disclose the contents of this > communication to others.> > > This email and any files transmitted with it are confidential and > intended solely for the use of the individual or entity to whom they are > addressed. If you have received this email in error please notify the > originator of the message. 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