Re: [rtcweb] Another approach to forking...

Harald Alvestrand <harald@alvestrand.no> Fri, 23 September 2011 13:28 UTC

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Date: Fri, 23 Sep 2011 15:30:53 +0200
From: Harald Alvestrand <harald@alvestrand.no>
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Subject: Re: [rtcweb] Another approach to forking...
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On 09/23/11 15:25, Hadriel Kaplan wrote:
> On Sep 23, 2011, at 8:58 AM, Harald Alvestrand wrote:
>
>> Just to confuse the forking issue still further:
>>
>> If the APIs remain as they are today, a JS application that wants to support forking can do the following:
>>
>> - Create a PeerConnection
>> - Cause it to generate an SDP blob ("SDP OFFER")
>> - Send that SDP blob out to be forked
>> - Throw away the PeerConnection
>> - As the answers come back, for each answer:
>>   - Create a new PeerConnection
>>   - Take out the SDP blob, put "SDP OFFER" at the top, and give it to the PeerConnection
> By this you mean take the answer and make it appear as an offer to PeerConn, right?
>
>
>>   - Throw away the generated "SDP ANSWER"
> But wouldn't the new PeerConn's be creating new ICE ufrag/passwords that won't match the one it created in the original PeerConn's offer, and thus not be able to successfully negotiate ICE with the peer(s)?
>
> And doesn't PeerConn create/allocate the IP:ports used for MediaStreams?  If so, each new PeerConn would also presumably be using a new UDP listen port and break this.
Oops. There was something I'd forgotten.

You're right - it won't work unless we create PeerConnections from the 
initial PeerConnection so that they can clone the ICE data and share the 
port.

Back to the drawing board. Thanks!

(in a previous API discussion I suggested a PeerConnectionFactory 
class.... nobody liked it at the time...)