IWA OWNER LGTM This is an extension to an existing IWA-only feature. Multicast introduces additional privacy concerns because since content is intended for consumption by multiple clients it cannot be encrypted in a way which preserves confidentiality (this has been previously discussed on this list an network-dev@). Requiring the user to explicitly choose to install an application rather than making this capability available to any site at least partially mitigates this concern. Reilly Grant | Software Engineer | [email protected] | Google Chrome <https://www.google.com/chrome>
On Fri, Oct 17, 2025 at 3:11 AM Chromestatus < [email protected]> wrote: > *Contact emails* > [email protected] > > *Explainer* > https://github.com/explainers-by-googlers/Multicast-in-Direct-Sockets > > *Specification* > https://github.com/WICG/direct-sockets/pull/79 > > *Design docs* > > > https://github.com/WICG/direct-sockets/blob/main/docs/multicast-explainer.md > > https://docs.google.com/document/d/1Wna0lkTrhYoTxOO1GjOrut2nWHO19HEyo9YCk39tXqY/edit?usp=sharing > > *Summary* > Allows Isolated Web Apps to subscribe to multicast groups and receive UDP > packets from there, and to specify additional parameters when sending UDP > packets to multicasts addresses. > > *Blink component* > Blink>Network->Direct Sockets > <https://issues.chromium.org/issues?q=customfield1222907:%22Blink%3ENetwork-%3EDirect%20Sockets%22> > > *Web Feature ID* > Missing feature > > *Motivation* > 1. Synchronous video stream from one device to the whole network of > devices. For example, imagine in a shopping mall there would be multiple > displays which show videos simultaneously on all devices. 2. Device > discovery on a local network. mDNS protocol uses multicast sockets under > the hood. In short, when a device joins a network, it sends a message: > “Hello, I am headphones-10, my ip is ‘20.20.20.14’ . Who else is here?”, > other devices reply and in such a manner all devices can know about each > other without a central server. > > *Initial public proposal* > https://github.com/WICG/proposals/issues/228 > > *TAG review* > Tag does not review Isolated Web Apps. It was stated publicly here > https://github.com/w3ctag/design-reviews/issues/842#issuecomment-2917031448 > > *TAG review status* > Not applicable > > *Risks* > > > *Interoperability and Compatibility* > Other browsers may choose to implement this API. > > *Gecko*: No signal > > *WebKit*: No signal > > *Web developers*: No signals > > *Other signals*: > > *Security* > Security and privacy considerations are explained > https://github.com/WICG/direct-sockets/blob/main/docs/multicast-explainer.md > Security considerations This API gives the opportunity to flood the network > with packets. By only providing this API to Isolated Web Apps the user > agent can be more confident that the application has not been compromised. > This allows users and system administrators to confidently grant this > capability to trusted applications. Additionally, routers have control, > whether they send multicast packets or drop them. In many setups dropping > multicast packets is the default setting. > > *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 information provided* > > > *Debuggability* > The code using this API can be debugged using the standard tools. > Integrating the API with the DevTools Networking tab to enable easier > introspection of the state of these connections as well as the data > transferred could be a beneficial future improvement. > > *Will this feature be supported on all six Blink platforms (Windows, Mac, > Linux, ChromeOS, Android, and Android WebView)?* > No > This feature is implemented on desktop platforms, although it will only be > available to the end users on platforms that support Isolated Web Apps, > which is currently only ChromeOS. Android is excluded for historical > reasons, although there are no apparent interoperability blockers here. > > *Is this feature fully tested by web-platform-tests > <https://chromium.googlesource.com/chromium/src/+/main/docs/testing/web_platform_tests.md>?* > No > Cannot be tested in WPT, the issue > https://github.com/web-platform-tests/wpt/issues/55304 > > *DevTrial instructions* > https://github.com/WICG/direct-sockets/blob/main/docs/multicast-how-to.md > > *Flag name on about://flags* > MulticastInDirectSockets > > *Finch feature name* > MulticastInDirectSockets > > *Rollout plan* > Will ship enabled for all users > > *Requires code in //chrome?* > False > > *Measurement* > Separate programmatic counters for the .idl methods and attributes (via > MeasureAs) are included to track the stats for API usage: > MulticastControllerJoinGroupFunction MulticastControllerLeaveGroupFunction > MulticastControllerJoinedGroupsAttribute > > *Availability expectation* > Feature is available only in Isolated Web Apps on desktop platforms. > https://chromestatus.com/feature/5146307550248960 > > *Adoption expectation* > Expected to be used initially by a small number of developers inside > Isolated Web Apps. > > *Adoption plan* > Working directly with developers that are planning to rely on the API. > > *Estimated milestones* > Shipping on desktop 144 > DevTrial on desktop 142 > > *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 > > *Link to entry on the Chrome Platform Status* > https://chromestatus.com/feature/5073740211814400?gate=5084202819256320 > > *Links to previous Intent discussions* > Intent to Prototype: > https://groups.google.com/a/chromium.org/d/msgid/blink-dev/68aeedee.050a0220.27f047.019b.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/68f21631.050a0220.29f70d.0062.GAE%40google.com > <https://groups.google.com/a/chromium.org/d/msgid/blink-dev/68f21631.050a0220.29f70d.0062.GAE%40google.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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