Re: [rtcweb] division of responsibilities (was: Draft agenda for IETF 87)

Martin Thomson <> Fri, 12 July 2013 16:04 UTC

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Date: Fri, 12 Jul 2013 09:04:58 -0700
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From: Martin Thomson <>
To: Stefan Håkansson LK <>
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Cc: "Cullen Jennings (fluffy)" <>, "<>" <>
Subject: Re: [rtcweb] division of responsibilities (was: Draft agenda for IETF 87)
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On 12 July 2013 00:35, Stefan Håkansson LK
<> wrote:
> To me it seems pretty straightforward to a certain point:
> * The SDP (if we opt to continue using SDP for this purpose) that goes
> on the signaling wire between the browsers is defined by IETF (and by
> the rtcweb WG I presume even though MMUSIC seems to have some stake)
> * JS APIs to:
> ** Apply an SDP (e.g. received on the signaling channel) to the browser
> ** Hand an SDP generated by the browser over to the application (for
> transmission over the signaling wire presumably)
> ** Influencing/modifying the contents of the SDP
> * All belongs to the W3C WebRTC
> What seems unclear to me is where we define what modifications to the
> SDP that are allowed - and when. Even though the ambition is to have
> APIs that makes SDP mangling an exception, we will still see that
> happening.

I can see how you would reach that conclusion, but it's only simple at
the most superficial level.

There needs to be a clear understanding about what information is
carried in SDP and what information is supplied by the application.  I
have observed that there is an assumption implicit in a lot of the
work that says that SDP carries everything it can possibly carry.
I'll note that this has been implicit, never explicit.  And the mere
existence of no-plan highlights the fact that there is a fundamental
disagreement on this point.

We've been building a consensus that is based on an assumption.  I'd
rather we had consensus than an untested assumption.  With all respect
to the chairs, that's not something I trust them to rule on at this