Intent to Ship: 'priority' HTTP request header

[Patrick Meenan]

Contact emails

pme...@google.com

Explainer

None

Specification

https://datatracker.ietf.org/doc/rfc9218

Summary

This feature adds the 'priority' request header for all HTTP requests with the priority information for the request at the time that it was sent. RFC 9218 (Extensible Prioritization Scheme for HTTP) defines a 'priority' HTTP request header to use for signaling request priority to origins (and intermediaries). It also defines negotiation processes and protocol-level frames for HTTP/2 and HTTP/3 to carry the same priority information. The header can only signal the initial priority for a resource when it was first requested while the frame-based mechanisms allow for modifying the priority after the fact. The header can operate end-to-end to the origin servers (and provide a mechanism for the origin to override the priority if recognized by intermediaries) while the frames are limited to operating on a link level. This feature is specifically for supporting the header-based prioritization scheme.

Blink component

Blink>Network

TAG review

None

TAG review status

Not applicable

Risks

Interoperability and Compatibility

None

Gecko: Shipped/Shipping
WebKit: Shipped/Shipping
Web developers: No signals
Other signals:

Security

The priority information for a given request is already exposed in HTTP/2 and HTTP/3 in the frame-based priority fields (and weights in HTTP/2). This moves the same information directly into the headers for HTTP/2 and HTTP/3 only.

WebView application risks

Does this intent deprecate or change behavior of existing APIs, such that it has potentially high risk for Android WebView-based applications?

None

Debuggability

The "Priority" header is exposed in both the Dev Tools network panel (in the Request Headers) and in the Netlog.

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

Yes

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

No

Request priorities are not standardized so the values themselves are not testable across browsers. The presence of the header at all requires HTTP/3 (or HTTP/2 for Chrome) which is not something that is currently possible to test in WPT.

Flag name on chrome://flags

Finch feature name

PriorityHeader

Requires code in //chrome?

False

Tracking bug

https://bugs.chromium.org/p/chromium/issues/detail?id=1404785

Measurement

N/A

Availability expectation

Feature will be available on all browsers once Chromium ships (already available in Safari and Firefox).

Adoption expectation

N/A

Adoption plan

N/A

Non-OSS dependencies

Does the feature depend on any code or APIs outside the Chromium open source repository and its open-source dependencies to function?

None

Estimated milestones

Shipping on desktop	124
OriginTrial desktop last	122
OriginTrial desktop first	120
DevTrial on desktop	119

Shipping on Android	124
OriginTrial Android last	122
OriginTrial Android first	120
DevTrial on Android	119

Shipping on WebView	124
OriginTrial webView last	122
OriginTrial webView first	120

Anticipated spec changes

None

Link to entry on the Chrome Platform Status

https://chromestatus.com/feature/5109106573049856

Links to previous Intent discussions

Intent to prototype: https://groups.google.com/a/chromium.org/g/blink-dev/c/eEeDzwtw5v0 Intent to Experiment: https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAPq58w5KJijit8ObBhWKzCnLjro7jSfAsxfPPZ66NwmTO_ZT%3Dg%40mail.gmail.com

This intent message was generated by Chrome Platform Status.

[Yoav Weiss (@Shopify)]

LGTM1

Thanks for catching us up here!

On Fri, Feb 16, 2024 at 4:15 PM Patrick Meenan <pme...@chromium.org> wrote:

Contact emails

pme...@google.com

Explainer

None

Specification

https://datatracker.ietf.org/doc/rfc9218

Summary

This feature adds the 'priority' request header for all HTTP requests with the priority information for the request at the time that it was sent. RFC 9218 (Extensible Prioritization Scheme for HTTP) defines a 'priority' HTTP request header to use for signaling request priority to origins (and intermediaries). It also defines negotiation processes and protocol-level frames for HTTP/2 and HTTP/3 to carry the same priority information. The header can only signal the initial priority for a resource when it was first requested while the frame-based mechanisms allow for modifying the priority after the fact. The header can operate end-to-end to the origin servers (and provide a mechanism for the origin to override the priority if recognized by intermediaries) while the frames are limited to operating on a link level. This feature is specifically for supporting the header-based prioritization scheme.

Blink component

Blink>Network

TAG review

None

TAG review status

Not applicable

Risks

Interoperability and Compatibility

None

Gecko: Shipped/Shipping
WebKit: Shipped/Shipping

Any links to shipping artifacts?

 

--
You received this message because you are subscribed to the Google Groups "blink-dev" group.
To unsubscribe from this group and stop receiving emails from it, send an email to blink-dev+...@chromium.org.
To view this discussion on the web visit https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAPq58w47qFBfznZH%3Ditr7-whRu3irmCTUxrpxKM5ySA%3DoA-yOg%40mail.gmail.com.

[Chris Harrelson]

LGTM2

To view this discussion on the web visit https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAOmohSKo9gBFFxwtstWATWsM1q0ZXEs4WkokDPF5K2ETRa9X3A%40mail.gmail.com.

[Alex Russell]

LGTM3

To unsubscribe from this group and stop receiving emails from it, send an email to blink-dev+unsubscribe@chromium.org.

To view this discussion on the web visit https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAPq58w47qFBfznZH%3Ditr7-whRu3irmCTUxrpxKM5ySA%3DoA-yOg%40mail.gmail.com.

--
You received this message because you are subscribed to the Google Groups "blink-dev" group.

To unsubscribe from this group and stop receiving emails from it, send an email to blink-dev+unsubscribe@chromium.org.