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Re: DataChannels in Workers

From: Stefan Håkansson LK <stefan.lk.hakansson@ericsson.com>
Date: Wed, 30 Sep 2015 06:43:32 +0000
To: Randell Jesup <randell-ietf@jesup.org>, "public-webrtc@w3.org" <public-webrtc@w3.org>
Message-ID: <1447FA0C20ED5147A1AA0EF02890A64B37351200@ESESSMB209.ericsson.se>
On 25/09/15 18:01, Randell Jesup wrote:
> Use-case:
> A number of applications using RTCDataChannels would benefit from being
> able to process the data and send data from a Worker.  An example of
> this is a game which handles state updates and other processing in a
> Worker, keeping the mainthread application free to handle rendering and
> UI interactions, and avoiding or minimizing GC pauses.
> Basic Mechanism:
> The RTCDataChannel would be a transferrable object, which can be sent
> via postMessage:
>     channel = createDataChannel("MyChannel", {});
>     // or we're in an ondatachannel callback/event triggered by the other
>     // side creating an RTCDataChannel
>     worker.postMessage(channel, [channel]);
>     // channel is now owned by the worker; no more events will occur on the
>     // sender's version of 'channel'
> The worker will receive the object, and can set event handlers on it.
> Handling of Events:
> After a transfer, all events occur in the worker, and the worker must
> set up event handlers to process them.  Any events that occur during the
> transfer, or that were queued to be fired in the sender, will be held
> until the worker gets the transferred object.  This means the worker
> should set EventHandlers on the channel immediately on receiving the
> channel.
> Close:
> The worker can call channel.close(), which will operate normally. If the
> PeerConnection is shut down via peerconnection.close(), or if the
> RTCDataChannel m=application line is renegotiated 'off', then the worker
> will receive a close event for the channel, as normal.
> An RTCDataChannel may be transferred at any time, and may be transferred
> more than once.
> ToDo: write a PR for the spec.  I believe this will be a fairly small
> change to the spec itself (and we've been indicating we want it), so I'd
> like to have this in 1.0.

This may be a rather small addition, but experience tells us that what 
seems small at the surface often has a lot of details that are not 
trivial to sort out.

Before the Seattle/Redmond meeting agreed that we would use the meeting 
to decide what is in and out of 1.0, and we agreed that for a new 
feature to be under consideration for being "in" there would have to be 
a concrete proposal on the table before the meeting.

For "DataChannels in Workers" there was not proposal before the meeting, 
and it was not discussed during the meeting.

For these reasons we think that it should not be part of 1.0. We like 
the idea, and encourage working further on it to learn more (and ideally 
gain both implementer and user experience), perhaps as a separate 
document describing an extension to 1.0.

Stefan for the chairs

Received on Wednesday, 30 September 2015 06:44:00 UTC

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