Intent to Continue Experimenting: Speculation Rules (Prefetch)

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Jeremy Roman

Sep 10, 2021, 1:52:03 PM9/10/21
to blink-dev

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Speculation Rules is a flexible syntax for defining what outgoing links are eligible to be prepared speculatively before navigation. It enables access to additional enhancements, such as use of a private prefetch proxy, where applicable.

Participants in this trial can use this syntax to request prefetching of links they expect the user is likely to visit next.

This is a request to extend the previous experiment, with the same limitations. We would like to extend the experiment for milestones M95 to M97 (inclusive), in order to continue to gather data as a partner makes improvements to their integration and to shave some of the rough edges off the implementation.

Blink component


TAG review

TAG review status



Interoperability and Compatibility

Gecko: No signal

WebKit: No signal

Web developers: Past success with <link rel=prefetch> and libraries like QuickLink, and discussion with some partners suggests interest in this space.

Goals for experimentation

To gather feedback about the convenience of the Speculation Rules syntax, and to gather data about performance improvements for navigations that are prefetched, directly and via a private prefetch proxy (subject to the limitations mentioned above).

Ongoing technical constraints

No significant technical constraints anticipated.

Will this feature be supported on all six Blink platforms (Windows, Mac, Linux, Chrome OS, Android, and Android WebView)?

Chrome for Android (non-WebView) only, at present.

Eventually other platforms will be supported.

Is this feature fully tested by web-platform-tests?

Not yet, but we have plans to.

Flag name

The origin trial feature name will continue to be SpeculationRulesPrefetch.

Tracking bug

Link to entry on the Chrome Platform Status

Links to previous Intent discussions

Intent to prototype:

Intent to experiment:

This intent message was generated by Chrome Platform Status.

Yoav Weiss

Sep 13, 2021, 11:56:40 PM9/13/21
to Jeremy Roman, blink-dev
LGTM to experiment M95-M97 (inclusive).
Note that for experimentation beyond that, it'd be useful to show a summary of learnings from the trial up until that point.

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