Thanks Ali. It's also useful to have a look at
https://groups.google.com/a/chromium.org/g/blink-dev/c/e3pZJu96g6c/m/X9HcrSkVAgAJ
for the high-level plan, in addition to the timelines post
<https://blog.chromium.org/2021/09/user-agent-reduction-origin-trial-and-dates.html>
which has timelines attached to it.
A 13 milestone timeline is pretty long, but our intention is to give the
ecosystem sufficient time for migration work. The breakdown looks like
so (summarizing the above links):
M100: launch deprecation trial 1 milestone ahead of first "reduction"
phase, in case a site needs minor version and hasn't migrated to UA-CH yet.
M101: reduce MINOR.BUILD.PATCH to "0.0.0"
M107: reduce rest of Desktop UA
M110: reduce rest of Mobile UA
M113: end deprecation trial, giving an extra buffer of 3 months in case
it's needed.
I believe most sites won't need 13 milestones to be ready, but we know
some large sites have very long release cycles and it seems worthwhile
to offer the extra time given the scope of the proposed changes.
On 1/26/22 10:37 AM, Ali Beyad wrote:
The timelines
<https://blog.chromium.org/2021/09/user-agent-reduction-origin-trial-and-dates.html>
post contains more details, but in summary:
We will start offering the deprecation OT in M100, to give at least
one release of integration time with the deprecation OT before the
initial phase of UA reduction commences in M101 (reducing the minor
version part of the UA string). And it would last until M113 (see
Phase 7 in the timelines post).
On Wed, Jan 26, 2022 at 10:26 AM Yoav Weiss <yoavwe...@chromium.org>
wrote:
This seems like a good thing to do, thanks!
What are the requested timelines for the deprecation trial?
On Tuesday, January 25, 2022 at 3:40:15 PM UTC+1 Ali Beyad wrote:
Contact emails
abe...@chromium.org <mailto:abe...@chromium.org>,
victor...@chromium.org <mailto:victor...@chromium.org>,
jadekess...@chromium.org, miketa...@chromium.org
Explainer
None
Specification
None
Summary
Before we proceed with User-Agent (UA) reduction, we want to
allow sites that are not yet ready for the reduced UA string
to get the full UA string, exposed in HTTP requests and in
navigator.userAgent, navigator.appVersion, and
navigator.platform, through a deprecation origin trial.
Design Doc
https://docs.google.com/document/d/1d-K43rzfDGxNM4H6Yzh5lV08KJwLsae06i4Q0A8snME
<https://docs.google.com/document/d/1d-K43rzfDGxNM4H6Yzh5lV08KJwLsae06i4Q0A8snME>
Blink component
Privacy>Fingerprinting
<https://bugs.chromium.org/p/chromium/issues/list?q=component:Privacy%3EFingerprinting>
TAG review
https://github.com/w3ctag/design-reviews/issues/640
<https://github.com/w3ctag/design-reviews/issues/640>
TAG review status
TBD, but we have positive signals
<https://github.com/w3ctag/design-reviews/issues/640#issuecomment-992698367>thus
far.
Risks
Interoperability and Compatibility
The compatibility risk is low, as we’re planning to send the
full UA string in the deprecation origin trial, which is an
existing behavior before UA reduction that sites already know
how to parse. The deprecation origin trial is there simply to
allow sites that aren’t yet prepared for the new behavior (the
reduced UA string) to continue to receive the old behavior
(the full UA string) for some time period.
As for interoperability, the concern is again low because the
deprecation origin trial is simply enabling
previously-existing behavior to continue to operate for the
sites that are enrolled.
Experiment Summary
The prerequisite of this trial is that developers know the
deprecation origin trial is a temporary measure to allow more
time to migrate off of the full UA string, and move to using
User-Agent Client Hints (UA-CH) instead. By the end of the
deprecation origin trial date, the Chrome browser will
exclusively send the reduced UA string.
The goal is to enable developers to ensure stability with our
proposed changes.
As for engaging with the trial itself, there will be two
components controlled by the same origin trial:
1.
Provide the full UA string in the associated Javascript
APIs, if the deprecation origin trial is enabled.
2.
A client hint that gets set when the deprecation origin
trial is enabled, where the client hint indicates to the
origin that the User-Agent request header contains the
full user agent value. Because of the experimental nature
of this client hint, a valid origin trial token must be
sent in the response header by the origin for the client
hint to take effect or be stored (in order to prevent
platform burn-in for this temporary client hint).
During the process of conducting the origin trial, we may find
that we need to request an exception to the per-site (and
possibly global) limits imposed by origin trials. In practice,
origin trials rarely exceed their quota limits, but if
necessary, there is time between when the limits have been
exceeded and the origin trial is turned off, where we can work
with the users on reducing their usage and/or lifting the limits.
Please see the design document describing the experiment for
more information.
Experiment Goals
The goal of this trial is to enable developers more time to
migrate away from the full UA string and move towards adoption
of UA-CH. Beginning in M101, we plan to send the reduced UA
string in a phased rollout
<https://blog.chromium.org/2021/09/user-agent-reduction-origin-trial-and-dates.html>approach.
For those sites that haven’t been able to migrate their
dependencies on the full UA string, the deprecation trial
affords them more time to do so.
We will be relying heavily on user and developer feedback to
identify where breakage occurs. We request feedback to be
provided in our GitHub repository
https://github.com/abeyad/user-agent-reduction
<https://github.com/abeyad/user-agent-reduction>. When the
deprecation origin trial is ready, we plan to publish
developer guidance on how to enroll and provide feedback in
the form of a blog post.
Experiment Risks
As the proposed changes are existing behavior, the experiment
risks are low. Site breakage can take many forms, both
obvious and non-obvious. However, since sites are in control
of the Origin-Trial and Accept-CH headers, a site can quickly
opt out of the experiment when breakage is encountered.
Is this feature fully tested byweb-platform-tests
<https://chromium.googlesource.com/chromium/src/+/master/docs/testing/web_platform_tests.md>?
No.
Flag name
#full-user-agent
Launch bug
https://bugs.chromium.org/p/chromium/issues/detail?id=1232573
<https://bugs.chromium.org/p/chromium/issues/detail?id=1232573>(for
UA reduction)
Tracking bug
https://bugs.chromium.org/p/chromium/issues/detail?id=1282230
<https://bugs.chromium.org/p/chromium/issues/detail?id=1282230>
Link to entry on the Chrome Platform Status
https://chromestatus.com/feature/5704553745874944
<https://chromestatus.com/feature/5704553745874944>
Links to previous Intent discussions
I2E for UserAgentReduction:
https://groups.google.com/a/chromium.org/g/blink-dev/c/R0xKm1B7qoQ/
<https://groups.google.com/a/chromium.org/g/blink-dev/c/R0xKm1B7qoQ/>
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