- From: Matthew Wilcox <mail@matthewwilcox.com>
- Date: Mon, 6 Feb 2012 20:17:05 +0000
On 6 Feb 2012, at 19:19, Bjartur Thorlacius wrote: > On Mon, 06 Feb 2012 18:58:00 -0000, Boris Zbarsky <bzbarsky at mit.edu> wrote: >> Again, it's not constant in the terms that the page sees, which are CSS pixels, not device pixels. >> > We're discussing HTTP here, so the content might just as well be raster bitmaps. Are we? Why, what makes HTTP the relevant factor? SPDY is the future and already supported in two major browsers., As it compresses headers and multiplexes, I don't see the issue. > Multiple and variable screen dimensions are quite common (in special for projection). That means a request for every screen the resource may be. For legacy HTTP servers that don't support the new and complicated If-Different-For-Device header that would have to be added would serve the same content once for every screen. No, it means we as a standards body define which gets sent. The sensible thing is to send the maximum screen size in use on the device. > So you have UAs sending extra headers with every request, making extra requests with even more extra headers in the fairly common case of variable screen dimensions (multiple screens) and either extra response headers for servers that use the feature (perfectly acceptable) and double round-trip lag (probably terrible) while the UA waits for the extra response header to check if there are alternative versions of the resource for differently sized screens and fetches the alternative version if there is one, or redundant fetching of *all* resources in proportion to the number of possible screen dimensions (assuming the best case of screen dimension being the only variable). Again, read the proposition I mentioned and you'll find non of this is true. Extra headers would only be sent by the browser if the browser received a request for the client to send those headers.
Received on Monday, 6 February 2012 12:17:05 UTC