Please review HTTP performance aspects of Incremental Font Transfer

[Chris Lilley <[e-mail]>]

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