Note: This intent email spans three Chromestatus entries for different sub-features that we experimented with together and would like permission to ship together in M121.
Contact emailsjbro...@chromium.org, adith...@chromium.org, isabo...@google.com, dome...@chromium.org, mc...@chromium.org Explainerhttps://github.com/WICG/nav-speculation/blob/main/triggers.md Specificationhttps://wicg.github.io/nav-speculation/speculation-rules.html Summary (1) An extension to speculation rules syntax that lets the browser obtain URLs for speculation from link elements in a page. They may include criteria which restrict which of these links can be used. (2) Adding the eagerness field to the speculation rules will let the developers control how eagerly the browser preloads links in order to balance the performance advantage against resource overhead. This field accepts one of "conservative", "moderate", "eager", or "immediate" strings as the value, and it is applicable to both "prefetch" and "prerender" actions and both "list" or "document" sources. If not explicitly specified, list rules default to "immediate" and document rules default to "conservative". (3) Currently developers can only specify speculation rules using inline script tags. The proposed feature provides an alternative through the "Speculation-Rules" header. Its value must be a URL to a text resource with "application/speculationrules+json" MIME type. The resource's rules will be added to the document's rule set. Blink componentInternals>Preload <https://bugs.chromium.org/p/chromium/issues/list?q=component:Internals%3EPreload> TAG reviewhttps://github.com/w3ctag/design-reviews/issues/721 TAG review statusIssues addressed (TAG still has reservations) Chromium Trial NameSpeculationRulesPrefetchFuture Link to origin trial feedback summary https://docs.google.com/document/d/13cJcoygFD64UcQH-P30dXCLbdD6SXpQwhpOUym64KXw/edit?usp=sharing Origin Trial documentation link https://github.com/WICG/nav-speculation/blob/main/chrome-2023q1-experiment-overview.md WebFeature UseCounter nameSpeculationRulesDocumentRules SpeculationRulesSelectorMatches SpeculationRulesHeader SpeculationRulesExplicitEagerness Risks Interoperability and Compatibility Because authors cannot rely on document rules being evaluated (or preloading generally), applications which use them should function correctly in other browsers and should continue to function correctly were the feature to be deprecated. Of course, ideally other browsers do find it compelling to implement this feature. Similar reasoning applies to the response header and eagerness field. *Gecko*: No signal ( https://github.com/mozilla/standards-positions/issues/620) *WebKit*: No signal (https://github.com/WebKit/standards-positions/issues/54 ) *Web developers*: Positive ( https://groups.google.com/a/chromium.org/g/blink-dev/c/L3mpXE1x3Zk/m/VvbMZrcsAQAJ) positive feedback from Akamai and use within Chrome on web.dev *Other signals*: Activation Some developers might not be immediately aware of which URLs they can prefetch or prerender without side effects; this risk is reduced if they primarily use the feature for same-origin URL patterns they are familiar with. Security See https://wicg.github.io/nav-speculation/speculation-rules.html#security-considerations . 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? Debuggability Speculative loading which occurs is visible in the Network panel and the new Preloading panel. Console warnings are logged when several types of issues are encountered. Will this feature be supported on all six Blink platforms (Windows, Mac, Linux, Chrome OS, Android, and Android WebView)?Yes (though some capabilities vary per platform) Is this feature fully tested by web-platform-tests <https://chromium.googlesource.com/chromium/src/+/main/docs/testing/web_platform_tests.md> ?Yes https://wpt.fyi/results/speculation-rules?label=experimental&label=master&aligned Some tests cover behavior which isn't enabled by default (even if experimental web platform features are on). Flag name on chrome://flags Finch feature nameSpeculationRulesPrefetchFuture Requires code in //chrome?False Tracking bughttps://bugs.chromium.org/p/chromium/issues/detail?id=1371522 https://bugs.chromium.org/p/chromium/issues/detail?id=1406595 https://bugs.chromium.org/p/chromium/issues/detail?id=1366940 Estimated milestones Shipping on desktop 121 OriginTrial desktop last 120 OriginTrial desktop first 110 Shipping on Android 121 OriginTrial Android last 120 OriginTrial Android first 110 OriginTrial webView last 120 OriginTrial webView first 110 Anticipated spec changes A URLPattern change was made to facilitate this, and document rules will be affected by upstream changes to URLPattern. Similarly, upstream changes to CSS selectors will affect document rules which use selectors to match. Some minor changes to how links are identified may happen in the future. We anticipate most changes to be compatible. Link to entry on the Chrome Platform Status https://chromestatus.com/feature/5112150536749056 https://chromestatus.com/feature/5091678266851328 https://chromestatus.com/feature/5069400512659456 Links to previous Intent discussionsIntent to prototype: https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CA%2B5JZsPqZakqnGx2zgreGEfRCJ1Xrr16cL2gcqGF7577dFhvsw%40mail.gmail.com Intent to Experiment: https://groups.google.com/a/chromium.org/g/blink-dev/c/3-0rLTZePzc/m/VNHWAdAGDQAJ Intent to Extend Experiment: https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CACuR13epuEiXzbO3HJq0O9eum5_parJYHWHuje7QztZRd-s56w%40mail.gmail.com This intent message was generated by Chrome Platform Status <https://chromestatus.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+unsubscr...@chromium.org. To view this discussion on the web visit https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CACuR13dJ%2BLypC7QmGmwvoGn3%2BhPs77bDa-NFDWTw0bA5WDhsWA%40mail.gmail.com.
