Intent to Experiment: Reverse Origin Trial for WebRTC's Plan B SDP semantics

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Henrik Boström

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Feb 18, 2021, 5:05:38 AMFeb 18
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Spec
WebRTC is a W3C Recommendation and multiple IETF standards:

The Session Description Protocol (SDP) used by WebRTC currently has two implementations:
  • "Unified Plan", the spec-compliant SDP format implemented by all browsers.
  • "Plan B", the non-standard SDP format that does not have a spec, is deprecated but not yet removed and is only implemented in Chromium-based browsers. JavaScript applications have access to it by using a non-standard API.
Summary
We want to remove the non-standard SDP format, "Plan B", from Chromium. Removal dates have already been announced, but in order to aid applications from migrating from Plan B to Unified Plan and to ensure we can keep the deadlines we have set, a Reverse Origin Trial is desired to give applications that opt-in more time to migrate.

Deadlines and rationale for Reverse Origin Trial were provided in the intent to deprecate. The target dates are:
  • M89 (Stable in February, 2021): Deprecation warning is added in the developer console.

  • M93 (Stable in August, 2021): Plan B is removed, with the option to extend this deadline by opting-in to a Reverse Origin Trial.

  • M96 (Stable in January, 2022): The extended deadline ends and Plan B is removed for everybody.

I would like to make the Reverse Origin Trial available as of M90 or M91 (when this CL lands).

Goals for experimentation
Unblock Plan B removal.

Experiment timeline
M90-M96.

Any risk when the experiment finishes?
If Plan B is removed while still in use, some applications would experience incompatibility issues when attempting to set up audio or video channels, especially in multi-participant conferencing setups. 1:1 calling will still work for some applications.

Ongoing technical constraints
N/A. There were some Unified Plan bugs and performance issues discovered that have been addressed in M90.

Debuggability
When using Plan B you will get a deprecation warning in the JS console. It will look different depending on if you have opted in to the Reverse Origin Trial.

Will this feature be supported on all five Blink platforms supported by Origin Trials (Windows, Mac, Linux, Chrome OS, and Android)?
Yes.

Link to entry on the feature dashboard
N/A, Unified Plan was shipped several years ago. Should I create an entry even for the Reverse Origin Trial?

Philip Jägenstedt

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Feb 18, 2021, 5:13:24 AMFeb 18
to Henrik Boström, blink-dev
LGTM per the plan in the Intent to Deprecate.

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Joe Medley

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Mar 2, 2021, 9:41:02 AMMar 2
to Henrik Boström, blink-dev
"Should I create an entry even for the Reverse Origin Trial?"

Yes, you should.
Joe Medley | Technical Writer, Chrome DevRel | jme...@google.com | 816-678-7195
If an API's not documented it doesn't exist.


Joe Medley

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Mar 2, 2021, 9:45:06 AMMar 2
to Henrik Boström, blink-dev
To be clear, Chrome Status isn't extra. It's a tool for creating intents and it tries to help you get everything needed for that. The option for Feature deprecation contains a stage for a reverse origin trial.

image.png

Joe Medley | Technical Writer, Chrome DevRel | jme...@google.com | 816-678-7195
If an API's not documented it doesn't exist.

Henrik Boström

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Mar 5, 2021, 10:41:12 AMMar 5
to blink-dev, Joe Medley, blink-dev, Henrik Boström

Joe Medley

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Mar 5, 2021, 12:48:03 PMMar 5
to Henrik Boström, blink-dev, Henrik Boström
Thank you!

Joe Medley | Technical Writer, Chrome DevRel | jme...@google.com | 816-678-7195
If an API's not documented it doesn't exist.

Henrik Boström

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Jul 8, 2021, 7:25:14 AMJul 8
to Yash Gogia, blink-dev, Joe Medley, Henrik Boström
Usage limits are not applied to Deprecation Trials so even if usage exceeds 0.5% this would not affect being able to use Plan B if opted in to the trial.

On Thu, Jul 8, 2021 at 12:29 PM Yash Gogia <yrg...@gmail.com> wrote:
Hi,

The guide that talks about origin trials, mentions that there is a built-in safeguard that automatically disables an experimental feature globally if its usage exceeds 0.5% of all Chrome page loads. 

Source: https://github.com/GoogleChrome/OriginTrials/blob/gh-pages/developer-guide.md#3-what-happens-if-a-large-site-such-as-a-google-service-starts-depending-on-an-experimental-feature

I would like to understand if this applies to reverse origin trials as well. From chrome status, it looks like the usage is hovering around 0.2% already and I am sure many more websites would add the trial as the August date for Chrome 93 approaches. A confirmation that this automatic cutoff would not apply to the reverse origin trial would give us a lot more confidence.

Thanks,
Yash

Yash Gogia

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Jul 8, 2021, 12:00:06 PMJul 8
to blink-dev, Joe Medley, blink-dev, Henrik Boström, Henrik Boström
Hi,

The guide that talks about origin trials, mentions that there is a built-in safeguard that automatically disables an experimental feature globally if its usage exceeds 0.5% of all Chrome page loads. 

Source: https://github.com/GoogleChrome/OriginTrials/blob/gh-pages/developer-guide.md#3-what-happens-if-a-large-site-such-as-a-google-service-starts-depending-on-an-experimental-feature

I would like to understand if this applies to reverse origin trials as well. From chrome status, it looks like the usage is hovering around 0.2% already and I am sure many more websites would add the trial as the August date for Chrome 93 approaches. A confirmation that this automatic cutoff would not apply to the reverse origin trial would give us a lot more confidence.

Thanks,
Yash
On Friday, 5 March 2021 at 23:18:03 UTC+5:30 Joe Medley wrote:

Abhi Shanmu

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Jul 29, 2021, 2:08:57 PMJul 29
to blink-dev, Yash Gogia, Joe Medley, blink-dev, Henrik Boström, Henrik Boström
Hi,

I am unable to find reverse origin trial listed in this page for me to register. 
https://developer.chrome.com/origintrials/#/trials/active
How can I register my domains for the reverse origin trial?
Thanks,
Abhi

Mike Taylor

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Jul 29, 2021, 4:55:18 PMJul 29
to Abhi Shanmu, Yash Gogia, Joe Medley, Henrik Boström, Henrik Boström, blink-dev
Hi Abhi,

Assuming you're looking for the deprecation trial ("reverse origin trial") for Plan B SDP semantics, https://developer.chrome.com/origintrials/#/view_trial/3892235977954951169 should be the right link.

(there's no visual differentiation between regular and deprecation trials in the UI, but maybe that would be a nice feature to add)

later,
Mike
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