Re: No-Vary-Search

[Mark Nottingham <[e-mail]>]

Hi Jeremy,

I don't think we've talked about it formally in the HTTP WG before, but some folks might recall that No-Vary-Search was discussed at the last HTTP Workshop:
  https://github.com/HTTPWorkshop/workshop2022/blob/main/talks/no-vary-search.pdf

I personally think it would be good to do this work in the HTTP WG, because it's not just browsers that want to do this -- it's also a common use case for proxy caches and CDNs. However, the interaction with being able to store more than one variant (which browsers currently don't do) needs to be thought through.

*chair hat on*

We've got a pretty tight agenda in Brisbane, but if you're interested, we might be able to squeeze in 5-10 minutes for a _very_ quick overview followed by discussion. Please tell us if you'd like to try.

Whether or not that happens, I'd be interested to hear what other folks think. 

Cheers,



> On 21 Feb 2024, at 13:08, Jeremy Roman <[e-mail]> wrote:
> 
> Hello HTTPWG:
> 
> This is tangentially unrelated to my previous email, but I've split it into another thread to avoid entangling the two.
> 
> A developer previously reported to us that their ability to use the prefetch cache was limited because their prefetch request URLs needed to include certain query parameters which are different from the navigation request URL, even though these URLs do not affect the resource the server ultimately produces (and therefore, the client can safely use the resource). The explainer we wrote goes through some of the possible use cases in more detail.
> 
> The semantics we have right now (and the header name, No-Vary-Search¹) are designed with the concept of being implementable in non-browser HTTP implementations, but since browser use cases were what we are focused on, there are some places where the semantics rely on, e.g., WHATWG URL, which may vary in subtle ways from other concepts of the meaning of the query string (since IETF HTTP doesn't currently take a position on that as far as I know).
> 
> The specification draft is currently hosted by the W3C's Web Incubator Community Group (WICG) and we've previously discussed it in a W3C context, but it was suggested that we bring it to HTTPWG's attention, too, and if there is interest among participants it could migrate to an HTTPWG RFC instead of continuing incubation in the web standards venues.
> 
> ¹ This was originally No-Vary-Query, but the web-exposed APIs call this part of the URL "search", so this change was requested in a W3C discussion.

--
Mark Nottingham   https://www.mnot.net/