mnot’s blog

Design depends largely on constraints.” — Charles Eames

Tuesday, 26 November 2002


Hixie, Mark and others are talking about serving up application/xhtml+xml selectively to browsers.

One question; how do you do this without either doing the wrong thing (e.g., if a shared cache in between stores a copy meant for, say, Mozilla, and then later serves it to IE), or completely killing cacheability (by using a Vary header which basically means that you’ll be blowing caches out with one entry per User-Agent string)?

I suppose you could stick Cache-Control: no-cache=”Content-Type” on the response, but you’d still be revalidating on every request, and I doubt whether most (if any) caches will properly implement these semantics.

Yes, application/xhtml+xml is correct, but it doesn’t seem worth blowing away the scalability mechanism of the Web to prove a point…

One Comment

Aaron Swartz said:

My code serves up the content-type based on Accept headers.

If caches can’t handle accept headers, then they’re broken.

Tuesday, November 26 2002 at 7:01 AM