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 WD of IFT was published today [1]

This specification defines two methods 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 work proposes a specific networking mechanism by which the 
client and server can negotiate  which IFT method to use [3], and to 
transfer requested subsets of the entire font [4][5]. Note too that Mark 
Nottingham has raised a performance concern for the Range Request method [6]

We would particularly value the review of the IETF HTTP WG on those 
aspects, although review of the entire specification would of course be 
most welcome.

Please feel free to raise issues on our GitHub repo [7].

[1] https://www.w3.org/TR/2022/WD-IFT-20220628/
[2] https://www.w3.org/TR/PFE-evaluation/
[3] https://www.w3.org/TR/2022/WD-IFT-20220628/#method-selection
[4] https://www.w3.org/TR/2022/WD-IFT-20220628/#extend-subset
[5] 
https://www.w3.org/TR/2022/WD-IFT-20220628/#browser-behaviors-subsequent-requests
[6] https://github.com/w3c/IFT/issues/74
[7] https://github.com/w3c/IFT/issues/

-- 
Chris Lilley
@svgeesus
Technical Director @ W3C
W3C Strategy Team, Core Web Design
W3C Architecture & Technology Team, Core Web & Media