Yes, there are plans for such a header, join the discussion here: https://github.com/WICG/nav-speculation/issues/138 However so far fleshing out its details was not deemed a blocker for releasing prerender - a simple "all or nothing" opt-out seemed sufficient as a first step.
On Wednesday, March 16, 2022 at 5:42:15 PM UTC+2 [email protected] wrote: > Hey Kouhei, > > Thanks for highlighting that there's an opt-out option now. I'm a little > concerned that it requires servers to avoid sending a response at all, > forcing an early decision by the infrastructure rather than allowing pages > requested this way to be prefetched by not prerendered (by, e.g., sending a > response header that says "prefetch is fine, but please don't render me"). > > Are there plans for such a header? It would go a long way to making me > comfortable with this feature. > > Regards > > On Tuesday, March 15, 2022 at 7:10:12 AM UTC-7 Kouhei Ueno wrote: > >> Hi, >> >> While we are discussing, we would like to continue the incremental roll >> out of the feature to non-Stable channels. As of now, we are testing out >> the feature on 60% of Dev/Canary channels, and 60% of Beta channels. The >> rollout is limited to Android Chrome (limitation of the current >> implementation). >> >> We expect the rollout to affect at most a tiny fraction of the Internet >> traffic generated by Chrome. The population of the Beta/Dev/Canary channels >> combined is less than a few percent of Stable population, and the >> navigation subject to prerendering on Prerendering-enabled Chrome is less >> than a percent. >> >> Let me try to summarize the state of the discussion here (including the >> questions we’ve received out-of-band). >> >> Q: Do you offer an opt-out mechanism to developers? >> >> A: Yes. The opt-out mechanism is now covered in this section >> <https://github.com/WICG/nav-speculation/blob/main/ua-initiated-prerendering.md#opting-out> >> >> of the explainer. >> >> Q: What can we do about prerender breaking “switch to already open tab” >> on WhatsApp? >> >> A: We are updating the BroadcastChannel interaction [spec >> <https://github.com/WICG/nav-speculation/issues/141>, implementation >> <https://chromium-review.googlesource.com/c/chromium/src/+/3517385>]. In >> addition, we are delaying ServiceWorker#postMessage too, to address a >> similar issue [crbug <https://crbug.com/1305120>] >> >> Q: Can Enterprise disable the feature by a policy? >> >> A: Yes - we respect the existing NetworkPredictionOptions >> <https://chromeenterprise.google/policies/#NetworkPredictionOptions> >> group policy. >> >> Q: What is the status of https://github.com/whatwg/html/issues/7533? >> >> A: The issue is a general “call for feedback” issue. Individual issues >> are tracked on wicg/nav-speculation issue tracker >> <https://github.com/WICG/nav-speculation/issues>. >> >> Q: Since prerendering risks breaking certain websites, what are the >> mitigation measures planned? >> >> A: >> >> Prerendering is not entirely new. It used to be available in Chrome M13 >> until M63 and has been available in many other browsers such as: Safari >> since at least 2014 >> <https://forums.macrumors.com/threads/safari-trying-to-pre-load-urls.1736761/>, >> >> Opera from 2017 >> <https://www.ghacks.net/2017/02/07/opera-43-better-performance-classic-link-selection/#:~:text=cursor%20vertically%20instead.-,Instant%20Page%20Loading,-Instant%20Page%20Loading>, >> >> and more recently launched in Edge. We assume that the risk of breakage is >> relatively low given these pre-existing conditions. That said, we will >> remain prudent while relaunching this feature. >> >> >> 1. >> >> Take a slow and transparent approach to our rollout: >> 1. >> >> We’ll be careful around ramping up the experiment group population >> that we will be monitoring the metrics and user reports closely. >> 2. >> >> We’ll also be transparent about the rollout config on this >> blink-dev thread. >> 3. >> >> We’ll be keeping in touch with various partners to ensure that >> everything is good on their end. >> 2. >> >> Before going to Stable, we’ll publish a heads-up article on one of >> our blogs with the following content: >> 1. >> >> What’s being experimented with (e.g. prerendering on Chrome for >> Android from the Omnibox) >> 2. >> >> Things to know about this feature (e.g. how it triggers, how it >> manifests itself, how it works) >> 3. >> >> How to do hands-on testing, what to do if something breaks (e.g. >> opt-out), how to share feedback to help us get this right. >> 3. >> >> Being as conservative as other prerendering browsers (such as Edge >> and Safari), as well as having the following extra mitigations: >> 1. >> >> Allowing developers to opt-outs. >> 2. >> >> Disabling prerendering on features known to be problematic or >> surprising (e.g. BroadcastChannel, Media, and Sensor APIs) >> >> >> -- >> >> Kouhei, on behalf of the Prerender2 team >> >> >> On Mon, Feb 21, 2022 at 1:48 AM Coco Trana <[email protected]> wrote: >> >>> >>> El dom., 20 de febrero de 2022 3:34 a. m., Noam Rosenthal < >>> [email protected]> escribió: >>> >> >>>> >>>> On Sun, Feb 20, 2022 at 12:10 PM Jacob G <[email protected]> wrote: >>>> >>>>> Maybe a weird side-effect, but think of web.whatsapp.com: You have >>>>> the tab open already, open a new tab, enter web.whatsapp.com, so >>>>> you'll get an action item in the omnibox to switch to the already open >>>>> tab >>>>> - but with prerendering this leads to web.whatsapp.com showing you've >>>>> opened the site in a new tab (even though you didn't - it got >>>>> prerendered), >>>>> making the "switch to already open tab" suggestion useless. >>>>> Is this something site maintainers will have to fix or on the chromium >>>>> side? (Prerendering interaction with already open tabs) >>>>> >>>> This is exactly the open issue discussed here: >>>> https://github.com/WICG/nav-speculation/issues/141 >>>> We want the default behavior to not create unexpected behavior such as >>>> the ones you've described. >>>> >>>>> -- >>>> >>> 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 on the web visit >>>> https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAGttnEWV-HxsXds4W-ZcH_Aro4uvG1%2BjLmkM9io6xApi8LpjGA%40mail.gmail.com >>>> >>>> <https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAGttnEWV-HxsXds4W-ZcH_Aro4uvG1%2BjLmkM9io6xApi8LpjGA%40mail.gmail.com?utm_medium=email&utm_source=footer> >>>> . >>>> >>> >> >> -- >> kouhei >> > -- 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 on the web visit https://groups.google.com/a/chromium.org/d/msgid/blink-dev/7bb9cb46-420e-4111-9be5-93eae359f606n%40chromium.org.
