Re: [rtcweb] SDP Offer/Answer draft-jennings-rtcweb-signaling - Scope

Christer Holmberg <> Tue, 18 October 2011 10:47 UTC

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From: Christer Holmberg <>
To: Iñaki Baz Castillo <>
Date: Tue, 18 Oct 2011 12:47:40 +0200
Thread-Topic: [rtcweb] SDP Offer/Answer draft-jennings-rtcweb-signaling - Scope
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Cc: Jonathan Rosenberg <>, "" <>, "" <>
Subject: Re: [rtcweb] SDP Offer/Answer draft-jennings-rtcweb-signaling - Scope
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>>>No, this is not a draft about a "default signaling protocol"
>>>for RTCweb. Wrong. This is just a protocol for 
>>>communication between the JavaScript code and the RTCweb stack in the browser. It 
>>>does NOT mandate how the signaling messages are sent on-the-wire.
>> Eventhough the draft does not suggest a default signaling 
>> protocol, I don't think that is completely true that it is 
>> only between the JS app and broswer. At least it's not very clear.
>> - Section 5.1 says: "ROAP messages are typically carried 
>> over a **reliable transport** (likely HTTP via XMLHttpRequest 
>> or WebSockets),..."
> Yes, that is because JavaScript code running in a browser can 
> only communicate via HTTP or WebSocket.

Yes, but the JS app and browser don't communicate with each other using HTTP or WebSockets.

>> - Section 5.3.3 defines an "OK" message, which is used to cease **re-transmissions** of the ANSWER.
> I expect that is a "guideline" for the signaling protocol implementor.
> There is no need for such "OK" message to be received from 
> the peer or server. The own JS code could generate it when 
> appropriate and pass it to its RTCweb stack.

Why? The browser is not going to re-transmit anything, is it?

>> - In addition, there is text talking about **ROAP signaling 
>> messages** (and gateways translating between those and SIP messages).
> That just means that, of course, ROAP must be carried within 
> some signaling protocol (obvious) so, in case of 
> interoperating with a SIP network a gateway is required 
> (unless you use SIP over WebSocket).

Yes, so that means ROAP messages will be carried over some signaling protocol - meaning ROAP is not only a protocol between the JS app and browser.

I just want to make sure everybody has the same understanding of the scope, because at least to me it is a little unclear.