[rtcweb] JSEP-24: canTrickleIceCandidiates question

Christer Holmberg <christer.holmberg@ericsson.com> Mon, 08 January 2018 11:39 UTC

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From: Christer Holmberg <christer.holmberg@ericsson.com>
To: "rtcweb@ietf.org" <rtcweb@ietf.org>
Thread-Topic: JSEP-24: canTrickleIceCandidiates question
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Date: Mon, 8 Jan 2018 11:39:05 +0000
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Subject: [rtcweb] JSEP-24: canTrickleIceCandidiates question
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Hi,

The W3C WebRTC spec says:

       "The canTrickleIceCandidates attribute indicates whether the remote
peer is able to accept trickled ICE candidates [TRICKLE-ICE
<https://www.w3.org/TR/webrtc/#bib-TRICKLE-ICE>]. The
        value is determined based on whether a remote description
indicates support for trickle ICE, as defined in [JSEP
<https://www.w3.org/TR/webrtc/#bib-JSEP>] (section 4.1.15.
        
<https://tools.ietf.org/html/draft-ietf-rtcweb-jsep-20#section-4.1.15>).
Prior to the completion of setRemoteDescription
<https://www.w3.org/TR/webrtc/#dom-rtcpeerconnection-setremotedescription>,
 
        this value is null.²

JSEP-24 says:

        "null:  No SDP has been received from the other side, so it is not
         known if it can handle trickle.  This is the initial value before
         setRemoteDescription() is called.²

         (Basically repeating the W3C text)

         Šand:


        "However, applications can use the canTrickleIceCandidates
property to determine whether their peer can
         actually do Trickle ICE, i.e., whether it is safe to send an
initial offer or answer followed later by
         candidates as they are gathered. As "true" is the only value that
definitively indicates remote
         Trickle ICE support, an application which compares
canTrickleIceCandidates against "true" will by default
         attempt Half Trickle on initial offers and Full Trickle on
subsequent interactions with a Trickle ICE-compatible
         agent.²


QUESTION: Since the value will be NULL before completion of
setRemoteDescription (before SDP has been received from the other side)
how can the value be used by applications for initial offers?

Regards,

Christer