Intent to Implement and Ship: Presentation Receiver API 1-UA Mode
mark a. foltz
Contact emails
zha...@chromium.org, mfo...@chromium.org
Spec
https://w3c.github.io/presentation-api/#interface-presentationreceiver
TAG Review: https://github.com/w3ctag/spec-reviews/blob/master/2015/presentation-api.md
Summary
Currently, the Presentation API in Chrome only allows presentation of specific URLs that correspond to Cast or DIAL applications. These URLs are interpreted by Chrome to trigger the launching of the corresponding app on the presentation display. This mechanism is called “2-UA mode”, as the remote device is responsible for rendering the content.
We are preparing to ship “1-UA mode.” In this mode any URL can be passed into the API and shown on the presentation display. In 1-UA mode, the presented document is rendered locally in an offscreen tab, which is captured and mirrored to the target display, using Cast Streaming (for Cast-enabled displays) or WebRTC (for cloud-accessible displays). The presented document exchanges messages with the controlling (initiating) document via the navigator.presentation.receiver API.
Motivation
Currently there is no cross-browser way to render Web content on a presentation display. Web developers are forced to write display-specific apps and control them through SDKs that are specific to that display technology.
Shipping 1-UA mode is important for demonstrating interoperability with other browsers, and will enable us to promote use of the API among Web developers.
Interoperability and Compatibility Risk
This improves the interoperability of the Presentation API. Mozilla is implementing 1-UA mode as well which was demoed at TPAC 2016 and has landed in Firefox for Android nightly. This will provide two interoperable implementations of the API.
There are no users of navigator.presentation.receiver that we are aware of. Existing uses of PresentationRequest fall in the category of “proprietary app URLs” which will be excluded from 1-UA mode, so there is not a significant compatibility concern.
Ongoing technical constraints
None.
Will this feature be supported on all six Blink platforms (Windows, Mac, Linux, Chrome OS, Android, and Android WebView)?
It will be supported on all desktop platforms.
Support for Android will come at a later date. The lack of support will be visible by the web page as no device available. Presentation API is not supported on WebView.
OWP launch tracking bug
https://bugs.chromium.org/p/chromium/issues/detail?id=525660
Link to entry on the feature dashboard
https://www.chromestatus.com/feature/5414209298890752
Requesting approval to ship?
Yes. We are awaiting security reviews, so tentatively M57 but may slip to M58.
Chris Harrelson
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TAMURA, Kent
Software Engineer, Google
Dimitri Glazkov
LGTM2
LGTM1
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