Re: [rtcweb] JSEP: Relaxing SDP O/A rules?
Kaiduan Xie <kaiduanx@gmail.com> Wed, 03 October 2012 13:42 UTC
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Date: Wed, 03 Oct 2012 09:42:51 -0400
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From: Kaiduan Xie <kaiduanx@gmail.com>
To: Christer Holmberg <christer.holmberg@ericsson.com>
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Cc: "rtcweb@ietf.org" <rtcweb@ietf.org>
Subject: Re: [rtcweb] JSEP: Relaxing SDP O/A rules?
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There was a discussion on this, http://www.ietf.org/mail-archive/web/rtcweb/current/msg05141.html However I have not seen how the IETF webrtc work group address this issue. /Kaiduan On Wed, Oct 3, 2012 at 9:03 AM, Christer Holmberg <christer.holmberg@ericsson.com> wrote: > Hi, > > I've been looking at the O/A state machine, and the associated procedure > text, in section 4.2 of draft-jsep, and a couple of issues. > > First, the text says: > > "As in [RFC3264], an offerer can send an offer, and update it as > long as it has not been answered." > > That is not true. In order to update an offer (before it has been answered), > one needs to cancel the previous offer. > > > Second, the text says: > > "A description used as a "pranswer" may be applied as a response to > an "offer", or an update to a previously sent "answer"." > > I don't understand the update-to-a-previously-sent-answer thing. I don't > understand why one would update an "answer" with a "preanswer". > > And, the state machine doesn't seem to support it either. So, if done, what > state will I be in after such action? Can I then also send a new "answer", > to update the "preanswer" that updated the "answer"? > > > Third, is there a reason why a new "offer" can't be sent once in the > "Preanswer" state? > > > Regards, > > Christer > > > > > > -----Original Message----- > From: Martin Thomson [mailto:martin.thomson@gmail.com] > Sent: 2. lokakuuta 2012 22:00 > To: Christer Holmberg > Cc: rtcweb@ietf.org > Subject: Re: [rtcweb] JSEP: Relaxing SDP O/A rules? > > On 2 October 2012 11:00, Christer Holmberg <christer.holmberg@ericsson.com> > wrote: >> There has also been ideas about JSEP "relaxing" the SDP O/A rules. > > JSEP already does that. > > PRANSWER is probably the most obvious diversion, but it goes deeper. > > There's a simple view of what JSEP is and it goes a little like this: > > - SDP provides a description of the session that you are going to create [1] > > - You need two SDP blobs so that you can get all the non-negotiated > parameters like crypto and candidate attributes > > - setLocalDescription and setRemoteDescription provide a way of matching up > two SDP blobs into a complete session description > > - negotiation is performed outside this machine, and the browser can help > you with that in two ways: providing createOffer and createAnswer to build > the SDP; and by nudging you with a negotiatedneeded event when it learns of > things that necessitate changes. > > Obviously, it's a little more nuanced than that, but if you take this view, > you are more likely to get something to work. > > --Martin > > [1] Caveat: PRANSWER adds a layer of complexity to this by shifting part of > the session description to the offer rather than the answer > > > _______________________________________________ > rtcweb mailing list > rtcweb@ietf.org > https://www.ietf.org/mailman/listinfo/rtcweb >
- [rtcweb] JSEP: Relaxing SDP O/A rules? Christer Holmberg
- Re: [rtcweb] JSEP: Relaxing SDP O/A rules? Kaiduan Xie
- Re: [rtcweb] JSEP: Relaxing SDP O/A rules? Martin Thomson
- Re: [rtcweb] JSEP: Relaxing SDP O/A rules? Christer Holmberg
- Re: [rtcweb] JSEP: Relaxing SDP O/A rules? Kaiduan Xie
- Re: [rtcweb] JSEP: Relaxing SDP O/A rules? Martin Thomson
- Re: [rtcweb] JSEP: Relaxing SDP O/A rules? Harald Alvestrand
- Re: [rtcweb] JSEP: Relaxing SDP O/A rules? Christer Holmberg
- Re: [rtcweb] JSEP: Relaxing SDP O/A rules? Christer Holmberg
- Re: [rtcweb] JSEP: Relaxing SDP O/A rules? Martin Thomson
- Re: [rtcweb] JSEP: Relaxing SDP O/A rules? Christer Holmberg
- Re: [rtcweb] JSEP: Relaxing SDP O/A rules? Martin Thomson
- Re: [rtcweb] JSEP: Relaxing SDP O/A rules? Cullen Jennings (fluffy)
- Re: [rtcweb] JSEP: Relaxing SDP O/A rules? Christer Holmberg
- Re: [rtcweb] JSEP: Relaxing SDP O/A rules? Harald Alvestrand
- Re: [rtcweb] JSEP: Relaxing SDP O/A rules? Martin Thomson
- Re: [rtcweb] JSEP: Relaxing SDP O/A rules? Roman Shpount
- Re: [rtcweb] JSEP: Relaxing SDP O/A rules? Christer Holmberg
- Re: [rtcweb] JSEP: Relaxing SDP O/A rules? Christer Holmberg
- Re: [rtcweb] JSEP: Relaxing SDP O/A rules? Martin Thomson
- Re: [rtcweb] JSEP: Relaxing SDP O/A rules? Parthasarathi R
- Re: [rtcweb] JSEP: Relaxing SDP O/A rules? Christer Holmberg
- Re: [rtcweb] JSEP: Relaxing SDP O/A rules? Christer Holmberg
- Re: [rtcweb] JSEP: Relaxing SDP O/A rules? Cullen Jennings (fluffy)
- Re: [rtcweb] JSEP: Relaxing SDP O/A rules? Cullen Jennings (fluffy)
- Re: [rtcweb] JSEP: Relaxing SDP O/A rules? Cullen Jennings (fluffy)
- Re: [rtcweb] JSEP: Relaxing SDP O/A rules? Roman Shpount
- Re: [rtcweb] JSEP: Relaxing SDP O/A rules? Christer Holmberg
- Re: [rtcweb] JSEP: Relaxing SDP O/A rules? Christer Holmberg
- Re: [rtcweb] JSEP: Relaxing SDP O/A rules? Cullen Jennings (fluffy)
- Re: [rtcweb] JSEP: Relaxing SDP O/A rules? Paul Kyzivat
- Re: [rtcweb] JSEP: Relaxing SDP O/A rules? Paul Kyzivat