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Explainer https://github.com/WICG/compression-dictionary-transport Specification https://datatracker.ietf.org/doc/draft-ietf-httpbis-compression-dictionary/ Design docs https://docs.google.com/document/d/1IcRHLv-e9boECgPA5J4t8NDv9FPHDGgn0C12kfBgANg/edit https://github.com/WICG/compression-dictionary-transport https://datatracker.ietf.org/doc/draft-ietf-httpbis-compression-dictionary/ Summary An Origin Trial for Compression Dictionary Transport was scheduled to start in Chrome 117 and end in Chrome 122. But due to a critical issue, we could not start <https://groups.google.com/a/chromium.org/g/blink-dev/c/NgH-BeYO72E/m/G8fasgKdAQAJ> the Origin Trial until Chrome 119. The design of the feature has also evolved during the origin trial and RFC process. We’d like to continue the Origin Trial to get more feedback on the updated <https://chromium.googlesource.com/chromium/src/+/40d4e43a01431f680d5e682aaa2c4a543c8f0200/docs/experiments/compression-dictionary-transport.md#changes-in-m123> feature. Blink component Blink>Network <https://bugs.chromium.org/p/chromium/issues/list?q=component:Blink%3ENetwork> TAG review https://github.com/w3ctag/design-reviews/issues/877 TAG review status Closed RisksInteroperability and Compatibility Interoperability and Compatibility risk are low. This feature introduces a new compression method for transporting resources over HTTP. Web sites can know the browser support for the new feature by checking `document.createElement('link').relList.supports('dictionary')`. Also web servers can know the browser support by checking the `Accept-Encoding` request header and the new `Use-As-Dictionary` request header. This feature is an opt-in feature. And the dictionary storage is isolated using the top level site and the frame origin as the key. That means, if there is no dictionary registered for the site, the behavior of Chrome will not change while browsing the site. Also this feature is only usable within a secure-context so this feature will not increase the risk of having network proxies meddle with the content’s encoding. For enterprises that have deployed HTTPS-intercepting proxies that do not properly handle unknown encodings there is an enterprise policy exposed to disable the feature. Gecko: Positive (https://github.com/mozilla/standards-positions/issues/771) WebKit: No signal (https://github.com/WebKit/standards-positions/issues/160) Web developers: Positive Other signals: Ergonomics To reduce memory usage in network services, dictionary metadata is stored in a database on disk. And to avoid performance degradation for normal requests that do not use a dictionary, the reading of this metadata is designed not to block network requests. In other words, if the reading of metadata from the database is not completed before the request header is ready to be sent to the server, the dictionary may not be used even if it is already registered in the database. Activation To adopt this feature, web developers need to make changes in their web servers or build processes for static resources. Currently there is no major server software which supports compression dictionaries. Some CDNs have shared interest in supporting shared dictionary compression (e.g. publicly mentioned <https://blog.cloudflare.com/this-is-brotli-from-origin/#:~:text=One%20development%20that%20we%27re%20particularly%20focused%20on%20is%20shared%20dictionaries%20with%20Brotli.> in a blog post by Cloudflare). Security Chrome registers the response as a dictionary only when the response is CORS-readable from the document origin. Also we use a registered dictionary to decompress the response only when the response is CORS-readable from the document origin. Additionally, the dictionary and the compressed resource are required to be from the same origin as each other. So this should not introduce any new attack vector of information leaks. The dictionaries are partitioned with the storage cache and are cleared whenever cookies or cache is cleared to ensure that the dictionaries can not be abused as a tracking vector. 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? No Goals for experimentation We would like to collect feedback on the updated API design of Compression Dictionary Transport feature. Also, we would like to continue some experiments using this feature to measure its performance impact. Ongoing technical constraints None Debuggability We have introduced chrome://net-internals/#sharedDictionary. Using it, web developers can manage the registered dictionaries. Also web developers can check the related HTTP request and response headers (Use-As-Dictionary, Sec-Available-Dictionary, Accept-Encoding, Content-Encoding). Will this feature be supported on all six Blink platforms (Windows, Mac, Linux, Chrome OS, Android, and Android WebView)? Yes Is this feature fully tested by web-platform-tests <https://chromium.googlesource.com/chromium/src/+/main/docs/testing/web_platform_tests.md> ? No. We will rewrite some browser_tests to WPT. Flag name on chrome://flags chrome://flags/#enable-compression-dictionary-transport-backend chrome://flags/#enable-compression-dictionary-transport Finch feature name CompressionDictionaryTransportBackend CompressionDictionaryTransport Requires code in //chrome? True Tracking bug https://crbug.com/1413922 Launch bug https://launch.corp.google.com/launch/4266286 Estimated milestones OriginTrial desktop last 125 OriginTrial desktop first 123 OriginTrial Android last 125 OriginTrial Android first 123 Link to entry on the Chrome Platform Status https://chromestatus.com/feature/5124977788977152 Links to previous Intent discussions Intent to prototype: https://groups.google.com/a/chromium.org/g/blink-dev/c/-qYpLo9DTjw/m/JX6kbUOtBQAJ Intent to experiment: https://groups.google.com/a/chromium.org/g/blink-dev/c/NgH-BeYO72E/m/oup5DpbxAAAJ -- You received this message because you are subscribed to the Google Groups "blink-dev" group. 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