[webkit-dev] X-Purpose on prefetching requests

Maciej Stachowiak mjs at apple.com
Tue Sep 28 16:33:51 PDT 2010

On Sep 28, 2010, at 4:16 PM, Adam Barth wrote:

> I guess I don't understand your perspective.  Are you arguing that
> prefetch is a misfeature and folks should use image tags instead?
> That doesn't really make sense to me.  For example, using an explicit
> prefect API means the prefetch gets properly prioritized and doesn't
> delay the load event.  Below you characterize prefetch as a hack, but
> it seems like a useful feature that's used by a bunch of sites.
> As for X-Purpose, sometimes you seem to be saying that it can't be
> used correctly, whereas other times you seem to be saying that it can
> be used correctly, just that sites will screw it up.  At the beginning
> of the discussion, you seemed worried about the size increase to
> requests.  Reading your messages, it feels like you don't like
> X-Purpose, but you're not quite sure why.  As the discussion
> progresses, your reasons for disliking it seem to shift.
> Server operators seem to be sad that we're don't have the same feature
> as Firefox.  I don't understand why we shouldn't make them happier.

I'll try to find out the reasons we added "X-Purpose: preview" to Safari's snapshot fetcher. If similar use cases apply to prefetch, then that seems like a strong argument to add "X-Purpose: prefetch".


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