- From: Arvind Jain <arvind@google.com>
- Date: Tue, 2 Jul 2013 19:48:51 -0700
- To: Jatinder Mann <jmann@microsoft.com>
- Cc: Robin Berjon <robin@w3.org>, Philippe Le Hegaret <plh@w3.org>, public-web-perf <public-web-perf@w3.org>, Chris Bentzel <cbentzel@google.com>
- Message-ID: <CAOYaDdOPdiyZG+N8jSK4n2Yscm6SpqKYCrP_M1Tj-C3rZuVhXA@mail.gmail.com>
I agree with this. Re. "a" and "area" elements, I agree it applies there. Per Robin's suggestion, I'll send this to HTML WG. Arvind On Tue, Jul 2, 2013 at 4:01 PM, Jatinder Mann <jmann@microsoft.com> wrote: > Robin, > > Prefetch and prerender, while similar concepts, are different enough that > we would want to have developers specify when they want one versus the > other. From a resource utilization point of view, prefetch is relatively > cheap compared to prerender, as the browser is just downloading the HTML as > opposed to creating a hidden tab and navigating to it. The difference here > is the browser is only exercising the networking subsystem for prefetch, > but exercising all the subsystems for prerender (e.g., network, HTML > parsing, CSS parsing, JavaScript, DOM, formatting, block building, layout, > rendering, etc.). > > From a developer point of view, both features have value. For example, a > news site may want to prefetch the root HTML for all of the articles on the > page, since the pages are new and unlikely to be cached. On the other hand, > to conserve system resources, the browser may limit the number of pages it > will prerender, so we’d want the developer to only mark pages with > prerender that they expect a high likelihood that the user will be > visiting. E.g., in the news site this may be the main headline article. If > we only provide the ‘prefetch’ tag and let the browser guess what this > means, the browser will be forced to guess whether the user just wanted to > cache that page or navigate to the page in a hidden tab, and may make > mistakes. > > I think we should keep both 'prefetch' and 'prerender'. > > Thanks, > Jatinder > > > -----Original Message----- > From: Robin Berjon [mailto:robin@w3.org] > Sent: Friday, June 21, 2013 3:59 AM > To: Philippe Le Hegaret > Cc: Arvind Jain; public-web-perf; Chris Bentzel > Subject: Re: Prerender spec > > Hi all, > > I'm jumping in the middle of this with somewhat limited context, sorry if > I'm missing something. > > On 14/06/2013 18:56 , Philippe Le Hegaret wrote: > > On Fri, 2013-06-14 at 09:23 -0700, Arvind Jain wrote: > >> Do folks agree? Or should there be a separate document? > >> > > I guess it depends on the size and the level of buy-in. Usually, it's > > preferred to do an extension spec to start with but, in this case, it > > seems an overkill. > > I agree that an extension spec for this seems way overkill. The primary > advantage of doing that would be to not have to worry about synchronising > with us too much. But given the size of the feature I doubt that would be a > major issue. > > If you want to push this forward, I would recommend to start with simply > bringing it to the HTML WG as a proposal (in email, much like the below). > > My (personal) push-back on this would be about whether it is really > valuable for UAs, in addition to prefetch. Both prefetch and prerender are > hints, with behaviour largely left up to the UA. My question would > therefore be: what is that prevents a browser from seeing a prefetch link > and in fact prerendering it? Is this something that would not be decidable > subject to some given heuristics? Failing that — and perhaps more > importantly — are developers likely to choose between the two wisely? > > The latter question is particularly important, because if the answer tends > to be "no", then you're back to treating prefetch and prerender as the same > thing, and requiring some form of heuristic to decide when to load. > > Note that I'm not turning your proposal down here — I'm just pointing out > the questions that will need answering in order to move this forward. I'm > not a performance expert; the odds are that you have very good answers I > haven't thought of. > > > Any reason why this can't be applied to a and area elements, like > > prefetch? > > IMHO if it's on link it ought to be on those two as well. > > -- > Robin Berjon - http://berjon.com/ - @robinberjon > > > >
Received on Wednesday, 3 July 2013 02:49:18 UTC