Like you do say, the link header doesn't work for exactly the same reason - we'd have already flushed. It does seem like adding rel=prefetch to A and AREA may be the best solution.
On Thu, Jun 10, 2010 at 9:46 AM, Peter Beverloo <pe...@lvp-media.com> wrote: > On Thu, Jun 10, 2010 at 17:01, Eric Schurman <eri...@gmail.com> wrote: >> As described, the link prefetching capability seems to have some >> limitations that work counter to the performance of the page using it. >> >> It appears as though LINK elements are metadata elements and that >> these may only be supported inside the HEAD of the document. If so, >> then this is an issue in the real world, because at the time a web >> server flushes chunks containing the HEAD section of a document, the >> links we would want to prefetch are often not known. This is true for >> all the large sites I've analyzed or worked at. For example, many >> pages on a site will contain the same visual header, and we want to >> flush the HEAD and visual header content while the server is in the >> process of figuring out what the content of the page will be - which >> will contain the links we'd like to prefetch. >> >> Am I reading this correctly? Or is there a something that would allow >> the flushing scenario I describe above? >> >> One of the simplest approaches may be to add support for >> rel="prefetch" to A and AREA's, but it's been explicitly excluded from >> those. Why? >> >> Another approach could be to allow LINK throughout the document. This >> would allow for prefetching content like images even if you didn't >> know them at HEAD rendering time. >> >> Any opinions? >> > > While I have not found the original discussion about including the > prefetch relation in area and anchor tags, my guess would be that it's > a feature that would quite easily be abused by web authors. Adding > @rel="prefetch" to all anchors is a lot easier than putting them in > the header, so why not just preload every page on the site? Again, > someone else will probably have the answer you're looking for. > > Mozilla's Developer Center has a page about the attribute value[1] > which already suggests that they might add the feature on normal > anchor tags if there is sufficient interest in that. Their page also > contains a chapter about how to implement prefetching using the Link > HTTP header, which would be a solution if your website uses output > buffering. > > Considering you're specifically talking about flushing the header > before the links are known, however, I'm assuming that won't be a > possibility either. The link tag is specifically used for metadata > about the current document, so using that across the entire document > doesn't sound like a good idea to me. Despite the possibility of abuse > by authors, it seems to me that it's a fair use-case for including the > attribute. > > Regards, > Peter Beverloo > > [1] https://developer.mozilla.org/En/Link_prefetching_FAQ >
