Re: [rtcweb] API options for supporting fork with ROAP (Re: SDP Offer/Answer draft-jennings-rtcweb-signaling)
Harald Alvestrand <harald@alvestrand.no> Tue, 18 October 2011 11:10 UTC
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Date: Tue, 18 Oct 2011 13:10:18 +0200
From: Harald Alvestrand <harald@alvestrand.no>
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To: Iñaki Baz Castillo <ibc@aliax.net>
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Cc: Jonathan Rosenberg <jonathan.rosenberg@skype.net>, rtcweb@ietf.org, public-webrtc@w3.org
Subject: Re: [rtcweb] API options for supporting fork with ROAP (Re: SDP Offer/Answer draft-jennings-rtcweb-signaling)
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On 10/18/11 12:24, Iñaki Baz Castillo wrote: > 2011/10/18 Harald Alvestrand<harald@alvestrand.no>: >> I and some people from Ericsson had a discussion about forking the other day >> (the ability to send out one request and have it generate multiple >> PeerConnections on the response). >> >> Options include: >> >> - Sending a request with no content for which state must be kept, creating >> new PeerConnection objects on answer that can handle an answer without >> generating an offer first, and then renegotiating stuff that needs state >> subsequently >> - Creating a new "PeerConnectionFactoryWithOffer" object that holds the >> state of the request, but has the ability to mint several PeerConnections on >> responses >> - Throwing away the initial PeerConnection, munge the incoming Answer to >> look like an Offer, create a PeerConnection from it, and throw away the >> resulting Answer >> - Create the ability to create a PeerConnection from an Offer + an Answer, >> together with the ability to create an Offer without creating a >> PeerConnection (this is a variant of the Factory method) >> - Do something different..... > > Hi Harald, if I'm right the problem arises when the RTCweb client > generates a SDP/ROAP offer, sends it to the proxy/server and receives > more than one SDP/ROAP answer. The problem is that, currently, the > PeerConnection object just expects a single answer, am I right? Yes. My note was intended to point out that there's a number of API solutions here, but they all cost in terms of complexity. > The above options 1 and 3 require the RTCweb client to generate an > "INVITE" (let me name it INVITE) with no SDP/ROAP, which IMHO limits > too much some possible scenarios. In SIP world, sending an empty > INVITE means that the receiver could offer in the 200 OK response a > SDP offer with codecs not supported by the caller, so the caller must > send ACK and later a BYE. That's commonly ugly so I discourage its > usage for RTCweb. > > Said that, I strongly like your option 2 "Creating a new > PeerConnectionFactoryWithOffer". If I understand it properly, when a > RTCweb environment allows media forking, the RTCweb client should > create a PeerConnectionFactoryWithOffer object rather than a > PeerConnection. Then it sends the offer over the wire. Upon receipt of > each response with different ROAP/SDP answer, the object would > internally generate different PeerConnection objects (but the state of > all of them are governed by the PeerConnectionFactoryWithOffer > object). Am I right? Yes, that's right. One advantage of this approach is that the new class comes in addition to the normal PeerConnection class, so the interface for this functionality does not clutter up the interface for applications that don't want to deal with forking; they just never create such objects, and will reply to subsequent answers with "ERROR" (as they're always free to do). There are a number of additional details that need specification before this can be implemented, of course; we might want to delay that functionality beyond the first wave of releases.
- [rtcweb] SDP Offer/Answer draft-jennings-rtcweb-s… Cullen Jennings
- Re: [rtcweb] SDP Offer/Answer draft-jennings-rtcw… Iñaki Baz Castillo
- Re: [rtcweb] SDP Offer/Answer draft-jennings-rtcw… Iñaki Baz Castillo
- Re: [rtcweb] SDP Offer/Answer draft-jennings-rtcw… Ravindran Parthasarathi
- Re: [rtcweb] SDP Offer/Answer draft-jennings-rtcw… Iñaki Baz Castillo
- Re: [rtcweb] SDP Offer/Answer draft-jennings-rtcw… Ravindran Parthasarathi
- Re: [rtcweb] SDP Offer/Answer draft-jennings-rtcw… Iñaki Baz Castillo
- Re: [rtcweb] SDP Offer/Answer draft-jennings-rtcw… Ted Hardie
- Re: [rtcweb] SDP Offer/Answer draft-jennings-rtcw… Roman Shpount
- [rtcweb] API options for supporting fork with ROA… Harald Alvestrand
- Re: [rtcweb] SDP Offer/Answer draft-jennings-rtcw… Christer Holmberg
- Re: [rtcweb] API options for supporting fork with… Iñaki Baz Castillo
- Re: [rtcweb] SDP Offer/Answer draft-jennings-rtcw… Iñaki Baz Castillo
- Re: [rtcweb] SDP Offer/Answer draft-jennings-rtcw… Christer Holmberg
- Re: [rtcweb] SDP Offer/Answer draft-jennings-rtcw… Iñaki Baz Castillo
- Re: [rtcweb] API options for supporting fork with… Harald Alvestrand
- Re: [rtcweb] API options for supporting fork with… Iñaki Baz Castillo
- Re: [rtcweb] API options for supporting fork with… Stefan Håkansson LK
- Re: [rtcweb] SDP Offer/Answer draft-jennings-rtcw… Roy, Radhika R USA CIV (US)
- Re: [rtcweb] API options for supporting fork with… Iñaki Baz Castillo
- Re: [rtcweb] API options for supporting fork with… Stefan Håkansson LK
- Re: [rtcweb] SDP Offer/Answer draft-jennings-rtcw… Magnus Westerlund
- Re: [rtcweb] SDP Offer/Answer draft-jennings-rtcw… Iñaki Baz Castillo
- Re: [rtcweb] SDP Offer/Answer draft-jennings-rtcw… Eric Rescorla
- Re: [rtcweb] SDP Offer/Answer draft-jennings-rtcw… BeckW
- Re: [rtcweb] API options for supporting fork with… Roman Shpount
- Re: [rtcweb] SDP Offer/Answer draft-jennings-rtcw… Eric Rescorla
- Re: [rtcweb] SDP Offer/Answer draft-jennings-rtcw… Cullen Jennings
- [rtcweb] Why SDP answer needs and ack … was Re: S… Cullen Jennings
- Re: [rtcweb] SDP Offer/Answer draft-jennings-rtcw… Cullen Jennings
- [rtcweb] Forking -Re: SDP Offer/Answer draft-jenn… Cullen Jennings
- Re: [rtcweb] SDP Offer/Answer draft-jennings-rtcw… Cullen Jennings
- Re: [rtcweb] SDP Offer/Answer draft-jennings-rtcw… Iñaki Baz Castillo
- Re: [rtcweb] SDP Offer/Answer draft-jennings-rtcw… Ravindran Parthasarathi
- Re: [rtcweb] SDP Offer/Answer draft-jennings-rtcw… Cullen Jennings
- Re: [rtcweb] SDP Offer/Answer draft-jennings-rtcw… Cullen Jennings
- Re: [rtcweb] SDP Offer/Answer draft-jennings-rtcw… Harald Alvestrand
- Re: [rtcweb] Why SDP answer needs and ack … was R… Iñaki Baz Castillo
- Re: [rtcweb] Why SDP answer needs and ack … was R… Harald Alvestrand
- Re: [rtcweb] SDP Offer/Answer draft-jennings-rtcw… Stefan Håkansson
- Re: [rtcweb] API options for supporting fork with… Stefan Håkansson
- Re: [rtcweb] API options for supporting fork with… Harald Alvestrand
- [rtcweb] Draft name change: draft-holmberg-mmusic… Christer Holmberg
- Re: [rtcweb] API options for supporting fork with… Stefan Håkansson LK
- Re: [rtcweb] SDP Offer/Answer draft-jennings-rtcw… Christer Holmberg
- Re: [rtcweb] SDP Offer/Answer draft-jennings-rtcw… Christer Holmberg
- Re: [rtcweb] SDP Offer/Answer draft-jennings-rtcw… Christer Holmberg
- Re: [rtcweb] SDP Offer/Answer draft-jennings-rtcw… Christer Holmberg
- Re: [rtcweb] Forking - Re: SDP Offer/Answer draft… Christer Holmberg
- Re: [rtcweb] SDP Offer/Answer draft-jennings-rtcw… Cullen Jennings
- Re: [rtcweb] Forking - Re: SDP Offer/Answer draft… Cullen Jennings
- Re: [rtcweb] SDP Offer/Answer draft-jennings-rtcw… Cullen Jennings
- Re: [rtcweb] SDP Offer/Answer draft-jennings-rtcw… Cullen Jennings
- Re: [rtcweb] Why SDP answer needs and ack … was R… Cullen Jennings
- Re: [rtcweb] SDP Offer/Answer draft-jennings-rtcw… Marc Petit-Huguenin
- Re: [rtcweb] SDP Offer/Answer draft-jennings-rtcw… Cullen Jennings
- Re: [rtcweb] Why SDP answer needs and ack … was R… Randell Jesup
- Re: [rtcweb] Why SDP answer needs and ack … was R… Hadriel Kaplan
- Re: [rtcweb] SDP Offer/Answer draft-jennings-rtcw… Christer Holmberg
- Re: [rtcweb] SDP Offer/Answer draft-jennings-rtcw… Christer Holmberg
- Re: [rtcweb] SDP Offer/Answer draft-jennings-rtcw… Christer Holmberg
- Re: [rtcweb] SDP Offer/Answer draft-jennings-rtcw… Cullen Jennings
- Re: [rtcweb] SDP Offer/Answer draft-jennings-rtcw… Harald Alvestrand
- Re: [rtcweb] SDP Offer/Answer draft-jennings-rtcw… Christer Holmberg
- Re: [rtcweb] SDP Offer/Answer draft-jennings-rtcw… Cullen Jennings