Contact emailsorp...@google.com, boi...@google.com

ExplainerNone

Specificationhttps://w3c.github.io/webrtc-priority/#datachannel

Summary

Many applications have multiple media flows of the same data type and often
some of the flows are more important than others. The priority setting can
be used to indicate the relative priority of various flows. The priority
API allows the JavaScript applications to tell the browser whether a
particular media flow is high, medium, low or of very low importance to the
application.


Blink componentBlink>WebRTC>DataChannel
<https://bugs.chromium.org/p/chromium/issues/list?q=component:Blink%3EWebRTC%3EDataChannel>

Motivation

The WebRTC specification mandates that the underlying SCTP implementation
used for data channels uses a Weighted Fair Queue scheduler (see
https://www.rfc-editor.org/rfc/rfc8831#section-6.4). A Weighted Fair Queue
scheduler needs to know the relative priority of the different data streams
in order to be effective, which is taken from the
RTCDataChannelInit.priority and read back from the RTCDataChannel.priority
field.


Initial public proposalNone

TAG reviewNone

TAG review statusPending

Risks


Interoperability and Compatibility

This feature requires implementation of the SCTP ndata specification
(rfc8260) used by data channels. So far, only libwebrtc based browsers have
experimental support for it. If other browsers do not update their
implementation, communication will continue to work as it does today, so
risk is very limited.


*Gecko*: No signal

*WebKit*: No signal

*Web developers*: No signals

*Other signals*:

Activation

The feature relies on endpoints supporting the SCTP ndata specification
(rfc8260) which are currently uncommon. When the feature is launched, P2P
communication between Chrome and other libwebrtc based browsers will
automatically be upgraded to use stream priorities. If an endpoint does not
support rfc8260, communication will continue to work as-is.


Debuggability

No DevTools support for RTCDataChannel.


Is this feature fully tested by web-platform-tests
<https://chromium.googlesource.com/chromium/src/+/main/docs/testing/web_platform_tests.md>
?Yes

Tests are verifying that the negotiation of data channels propagates the
priority field as mandated in the DCEP specification (rfc8832). The tests
cannot verify that the underlying transport is respecting the priorities
reliably.


Flag name on chrome://flagsNone

Finch feature nameRTCDataChannelPriority

Requires code in //chrome?False

Estimated milestones

No milestones specified


Link to entry on the Chrome Platform Status
https://chromestatus.com/feature/5239327031033856?gate=4761533125754880

This intent message was generated by Chrome Platform Status
<https://chromestatus.com/>.

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