LGTM2 On Wed, Nov 4, 2026 at 5:24 PM Chris Harrelson <[email protected]> wrote:
> LGTM1 > > On Wed, Oct 28, 2026 at 11:20 PM 'Monica Chintala' via blink-dev < > [email protected]> wrote: > >> Thanks, Alex. We cannot measure the exact intersection, but existing >> UseCounters provide an upper bound. Access to WebTransport.datagrams >> peaked at 0.0126% of page loads over the last 30 days. For the common >> getReader({mode: "byob"}) pattern, the upper bound is 0.00232%, fewer than >> 1 in 43,000 page loads. >> >> The actual intersection may be lower because the BYOB counter covers all >> APIs. Affected applications can preserve the current behavior with >> datagramsReadableType: "bytes", and the change remains Finch-controlled >> for rollback. >> >> On Wednesday, October 28, 2026 at 8:32:01 AM UTC-7 Alex Russell wrote: >> >>> Is there an upper bound for potential breakage? Do we have metrics for >>> total use of datagram readable streams w/ BYOB behaviours? >>> >>> On Wednesday, October 28, 2026 at 7:35:15 AM UTC-7 Monica Chintala wrote: >>> >>>> We don’t have a metric for this exact usage pattern. The affected case >>>> is limited to applications requesting a BYOB reader without opting into >>>> "bytes". >>>> >>>> Default readers continue to work unchanged. Applications using BYOB can >>>> preserve the existing Chromium behavior by adding: {datagramsReadableType: >>>> "bytes"} >>>> >>>> This option can be added before rollout and works with both the old and >>>> new behavior. Firefox and Safari stable already use the new default. The >>>> rollout is Finch-controlled, so we can restore the previous default without >>>> a new release if compatibility problems are reported. >>>> >>>> On Tuesday, October 27, 2026 at 12:02:26 PM UTC-7 Alex Russell wrote: >>>> >>>>> What's the potential for breakage, given that we're changing default >>>>> behavior? Do our histograms tell us the fraction of pageloads that would >>>>> be >>>>> affected? >>>>> >>>>> Best, >>>>> >>>>> Alex >>>>> >>>>> On Wednesday, October 21, 2026 at 1:52:53 PM UTC-7 Chromestatus wrote: >>>>> >>>> *Contact emails* >>>>>> [email protected], [email protected] >>>>> >>>>> >>>>>> >>>>>> *Explainer* >>>>>> https://github.com/w3c/webtransport/blob/main/explainer.md >>>>>> >>>>>> *Specification* >>>>>> >>>>>> https://www.w3.org/TR/webtransport/#dom-webtransportoptions-datagramsreadabletype >>>>>> >>>>>> *Summary* >>>>>> Adds the WebTransportOptions.datagramsReadableType constructor >>>>>> option. By default, incoming WebTransport Datagrams are exposed through a >>>>>> default ReadableStream . Applications that require BYOB reading can >>>>>> request a readable byte stream by setting datagramsReadableType: >>>>>> "bytes" . >>>>>> >>>>>> *Blink component* >>>>>> Blink>Network>WebTransport >>>>>> <https://issues.chromium.org/issues?q=customfield1222907:%22Blink%3ENetwork%3EWebTransport%22> >>>>>> >>>>>> *Web Feature ID* >>>>>> webtransport <https://webstatus.dev/features/webtransport> >>>>>> >>>>>> *Motivation* >>>>>> WebTransport Datagrams are discrete messages rather than an >>>>>> undifferentiated byte sequence. A readable byte stream can lose empty >>>>>> Datagrams and can lose message boundaries when BYOB reads use a minimum >>>>>> byte count spanning multiple Datagrams. Making a default ReadableStream >>>>>> the default preserves Datagram boundaries and empty Datagrams. >>>>>> Applications >>>>>> that benefit from BYOB allocation control can explicitly opt into the >>>>>> byte-stream behavior. >>>>>> >>>>>> *Initial public proposal* >>>>>> *No information provided* >>>>>> >>>>>> *TAG review* >>>>>> Not applicable — this is a small incremental addition within the >>>>>> existing WebTransport specification. >>>>>> >>>>>> *TAG review status* >>>>>> Not applicable >>>>>> >>>>>> *Goals for experimentation* >>>>>> None >>>>>> >>>>>> *Risks* >>>>>> >>>>>> >>>>>> *Interoperability and Compatibility* >>>>>> Interoperability risk is low to medium. The API and default-stream >>>>>> behavior are defined in the WebTransport specification and covered by >>>>>> WPT. >>>>>> Firefox already uses a default non-byte stream when the option is >>>>>> omitted, >>>>>> but does not yet support the explicit "bytes" mode in current public >>>>>> test >>>>>> runs. Compatibility risk is mitigated by runtime gating. Chromium >>>>>> historically exposed the Datagram readable as a byte stream, so enabling >>>>>> the feature changes the default behavior: existing applications using a >>>>>> BYOB reader without specifying datagramsReadableType: "bytes" would >>>>>> fail. >>>>>> Applications using ordinary readers continue to receive Uint8Array >>>>>> chunks >>>>>> >>>>>> *Gecko*: Positive ( >>>>>> https://bugzilla.mozilla.org/show_bug.cgi?id=2007755) Firefox is >>>>>> implementing datagramsReadableType: "bytes" and BYOB Datagram reads >>>>>> >>>>>> *WebKit*: In development ( >>>>>> https://bugs.webkit.org/show_bug.cgi?id=319830) WebKit main >>>>>> implements the standardized datagramsReadableType option >>>>>> >>>>>> *Web developers*: Positive ( >>>>>> https://github.com/web-platform-tests/interop/issues/1121) The >>>>>> Interop 2026 WebTransport proposal received 28 👍 reactions. Developers >>>>>> also reported active WebTransport use and significant cross-engine >>>>>> differences. >>>>>> >>>>>> *Other signals*: >>>>>> >>>>>> *Ergonomics* >>>>>> Low. The default stream better matches Datagram message semantics. >>>>>> Applications needing BYOB allocation control must explicitly opt into >>>>>> "bytes" , making the semantic tradeoff visible in application code. >>>>>> >>>>>> *Activation* >>>>>> The main activation risk is existing Chromium-specific code assuming >>>>>> that transport.datagrams.readable always supports BYOB readers. Such >>>>>> applications must explicitly request datagramsReadableType: "bytes" . >>>>>> The >>>>>> feature remains experimentally gated while compatibility and >>>>>> interoperability are evaluated. >>>>>> >>>>>> *Security* >>>>>> Low. The option changes only the JavaScript stream adapter used to >>>>>> expose already-received Datagrams. It does not provide additional network >>>>>> access, expose new information, or alter WebTransport’s secure-context >>>>>> and >>>>>> connection security requirements. >>>>>> >>>>>> *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? >>>>>> Low. The implementation is cross-platform Blink code and requires no >>>>>> WebView-specific integration. The primary compatibility consideration is >>>>>> the same as Chrome: applications using a BYOB reader must explicitly >>>>>> request datagramsReadableType: "bytes" . >>>>>> >>>>>> >>>>>> *Debuggability* >>>>>> No feature-specific DevTools UI is required. Applications can inspect >>>>>> whether datagrams.readable supports BYOB by attempting to acquire a >>>>>> BYOB >>>>>> reader. Existing WebTransport logging, NetLog, and DevTools network >>>>>> diagnostics remain available for connection and Datagram issues. >>>>>> >>>>>> *Will this feature be supported on all six Blink platforms (Windows, >>>>>> Mac, Linux, ChromeOS, Android, and Android WebView)?* >>>>>> Yes >>>>>> Yes. Implemented in cross-platform Blink code without >>>>>> platform-specific dependencies. >>>>>> >>>>>> *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/webtransport/datagrams.https.any.html?label=experimental&label=master&aligned >>>>>> >>>>>> *Flag name on about://flags* >>>>>> chrome://flags/#enable-experimental-web-platform-features >>>>>> >>>>>> *Finch feature name* >>>>>> WebTransportDatagramsReadableType >>>>>> >>>>>> *Rollout plan* >>>>>> Will ship enabled for all users >>>>>> >>>>>> *Requires code in //chrome?* >>>>>> False >>>>>> >>>>>> *Tracking bug* >>>>>> https://issues.chromium.org/issues/547572475 >>>>>> >>>>>> *Availability expectation* >>>>>> WebKit has implemented the option and corresponding default-stream >>>>>> behavior in its main branch. Firefox implements the default non-byte >>>>>> stream >>>>>> behavior, although explicit "bytes" /BYOB mode does not yet pass current >>>>>> public WPT runs. Broad availability is expected as implementations >>>>>> converge >>>>>> on the WebTransport specification. >>>>>> >>>>>> *Adoption expectation* >>>>>> Adoption is expected mainly among WebTransport applications that use >>>>>> BYOB readers or need reliable preservation of Datagram message >>>>>> boundaries. >>>>>> Most applications using ordinary readers require no code changes. >>>>>> >>>>>> *Adoption plan* >>>>>> Adoption is expected through WebTransport documentation and Interop >>>>>> 2026 visibility. Existing Chromium applications using BYOB readers will >>>>>> need to explicitly set datagramsReadableType: "bytes" when the feature >>>>>> is >>>>>> enabled. >>>>>> >>>>>> *Estimated milestones* >>>>>> Shipping on desktop 159 >>>>>> DevTrial on desktop 155 >>>>>> Shipping on Android 159 >>>>>> DevTrial on Android 155 >>>>>> Shipping on WebView 159 >>>>>> >>>>>> *Anticipated spec changes* >>>>>> >>>>>> Open questions about a feature may be a source of future web compat >>>>>> or interop issues. Please list open issues (e.g. links to known github >>>>>> issues in the project for the feature specification) whose resolution may >>>>>> introduce web compat/interop risk (e.g., changing to naming or structure >>>>>> of >>>>>> the API in a non-backward-compatible way). >>>>>> None currently anticipated. The option and default-stream behavior >>>>>> are already defined in the WebTransport specification. >>>>>> >>>>>> *Link to entry on the Chrome Platform Status* >>>>>> >>>>>> https://chromestatus.com/feature/5148774971342848?gate=5517621058469888 >>>>>> >>>>>> *Links to previous Intent discussions* >>>>>> Intent to Prototype: >>>>>> https://groups.google.com/a/chromium.org/d/msgid/blink-dev/6aa86417.edf999b6.71d4e.0a07.GAE%40google.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 [email protected]. >> To view this discussion visit >> https://groups.google.com/a/chromium.org/d/msgid/blink-dev/2684f886-eeec-4900-b634-8cf8d497ca1an%40chromium.org >> <https://groups.google.com/a/chromium.org/d/msgid/blink-dev/2684f886-eeec-4900-b634-8cf8d497ca1an%40chromium.org?utm_medium=email&utm_source=footer> >> . >> > -- > 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 [email protected]. > To view this discussion visit > https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAOMQ%2Bw_HHFqMLJKZfK%2BnUqOpz0bA4MUDm4TQ9o7e3oaYh-vsgw%40mail.gmail.com > <https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAOMQ%2Bw_HHFqMLJKZfK%2BnUqOpz0bA4MUDm4TQ9o7e3oaYh-vsgw%40mail.gmail.com?utm_medium=email&utm_source=footer> > . > -- You received this message because you are subscribed to the Google Groups "blink-dev" group. 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