Re: Please review HTTP performance aspects of Incremental Font Transfer

[Chris Lilley <[e-mail]>]

Martin Thomson wrote:

 > The most obvious question is about why you would provide *two* 
mechanisms. Nothing explores why you might prefer one over the other, at 
server or client. It is simply taken for granted there there are two. I 
don't know how a client might be expected to use this specification in a 
sensible fashion based on the information presented. Nor how a server 
might choose to deploy one or the other.

Sorry that this wasn't clear. The simulation work to explore these two 
methods is described here:

https://www.w3.org/TR/PFE-evaluation/

or you could skip to the conclusions

https://www.w3.org/TR/PFE-evaluation/#conclusions

Basically Patch Subset gives clearly *much *better performance, but does 
require an intelligent server. Range Request gives worse performance (on 
slower networks, much worse than just requesting the entire font) but 
has the single advantage that a regular HTTP server can be used without 
modification, thus aiding self-hosted fonts where the content provider 
has no control over the server configuration.

We will make sure our spec also makes this clear (I thought it did 
already, but maybe only to someone already familiar with the earlier work).

For the technical points you raise, I would prefer to see those as 
GitHub issues so we can track the discussion over time, but I did want 
to make it clear how we came to have two separate methods.

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