Re: Please review HTTP performance aspects of Incremental Font Transfer

Thanks. From the looks of it, the actual fetching of the incremental font
files and patches don't do anything special with HTTP itself (and it looks
like there was work done to minimize round trips by processing and
generating a de-duped list of patches). Moving to stand-alone patch files
on larg(ish) boundaries will help with the edge caching of the files. It's
great to see the evolution from some of the earlier drafts.

I filed an issue but the one part that looked like it might be able to use
some more fleshing out is the local behavior of patched font files and how
they interact with the on-device caches (caching of patched files vs
re-processing all of the patches every time).

Thanks,

-Pat

On Wed, Jul 24, 2024 at 9:36 AM Chris Lilley <chris@w3.org> wrote:

> The Web Fonts WG requests review of the Incremental Font Transfer (IFT)
> specification by the IETF HTTP WG. A new Working Draft of IFT was published
> on 9 July 2024 [1]
>
> This specification defines a way to incrementally transfer fonts from
> server to client. Incremental transfer allows clients to load only the
> portions of the font they actually need which speeds up font loads and
> reduces data transfer needed to load the fonts. A font can be loaded over
> multiple requests where each request incrementally adds additional data.
>
> Earlier work [2] demonstrated the performance improvements in terms of
> bytes transferred and reduced network delay, for various network types.
>
> The current draft (unlike earlier drafts) does not require a dynamic web
> server to compute patches. Instead, a table of URLs to the pre-computed
> patches is contained within the subsetted font itself. This means that
> patches are applicable to multiple users, and are cacheable.
>
> Also (unlike earlier drafts, which used a custom patch request protocol)
> the patches are requested with a regular HTTP GET.
>
> We have an Explainer [3].
>
> We would particularly value the review of the IETF HTTP WG on the
> networking aspects, although review of the entire specification would of
> course be most welcome.
>
> Comments should be raised as individual issues on our GitHub [4].
>
> [1] https://www.w3.org/TR/2024/WD-IFT-20240709/
> [2] https://www.w3.org/TR/PFE-evaluation/
> [3] https://github.com/w3c/IFT/blob/main/IFT-Explainer.md
> [4] https://github.com/w3c/IFT
>
>
> --
> Chris Lilley
> @svgeesus
> Technical Director @ W3C
> W3C Strategy Team, Core Web Design
> W3C Architecture & Technology Team, Core Web & Media
>
>