Re: [rtcweb] Current state of signaling discussion

"Ravindran Parthasarathi" <> Tue, 18 October 2011 23:13 UTC

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Date: Wed, 19 Oct 2011 04:42:20 +0530
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Thread-Topic: [rtcweb] Current state of signaling discussion
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From: Ravindran Parthasarathi <>
To: Hadriel Kaplan <>, Eric Rescorla <>
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Subject: Re: [rtcweb] Current state of signaling discussion
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Hi Hadriel,

As you know in most of the IP real-time signaling protocol (SIP+SDP,
H.323(H.225, H.245), MGCP+SDP), there are two aspects

1) Signaling (SIP, H.225)
2) Media description (SDP offer/answer, H.245)

In case of Websocket or long poll HTTP, these protocol act as signaling
whereas media description is missing. ROAP will fill this signaling
protocol gap for websocket/HTTP.


>-----Original Message-----
>From: [] On
>Of Hadriel Kaplan
>Sent: Wednesday, October 19, 2011 2:35 AM
>To: Eric Rescorla
>Subject: Re: [rtcweb] Current state of signaling discussion
>In the abstract it states:
>"The protocol focuses solely on media negotiation and does not handle
>call control, call processing, or other functions."
>Ignoring esoteric stuff like session transfer, forwarding, etc. (ie,
>ignoring "phone" stuff) is fine.
>BUT, for an actual session protocol to work for even a gaming app, you
>need to do the following:
>1) determine a target for the ROAP message (ie, who's this OFFER going
>to in the end?)
>2) define how that target identity is conveyed (ie, how does the web
>server know which browser to give this ROAP OFFER to?)
>3) define a source identity model, possibly with authentication (ie,
>are you?)
>4) define how the source identity is conveyed (ie, how does the
>server/far-end-browser know who's calling?)
>5) define a end-of-session indication
>6) define a keep-alive mechanism, for when the far end goes away
>silently and (5) doesn't apply
>And I've probably missed some other things.
>On Oct 18, 2011, at 4:50 PM, Eric Rescorla wrote:
>> Is this actually correct? The introduction of that draft suggests
>> "The protocol is designed to operate between two entities (browsers
>> for example), which exchange messages "directly" - meaning that a
>> message output by one entity is meant to be directly processed by the
>> other entity without further modification. In practice, this means
>> that a web server can treat ROAP messages as opaque and just shuffle
>> them between browser instances. This allows for simple
>> implementations."
>> If we take the PeerConnection API as our point of reference, isn't
>> idea here that
>> you would instantiate callbacks that take messages coming out of the
>> PeerConnection
>> API and push them to the Web server and messages coming from the Web
>> and push them to the PeerConnection instance. I don't know if this is
>20 lines
>> of code (though with JS minimization it might be one line of code
>> but it does
>> seem comparatively trivial...
>> -Ekr
>> -Ekr
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