On Jul 21, 2009, at 9:15 PM, Adrian Bateman wrote:
I don't think the problem is that we couldn't build yet another cache that is similar but different to the AppCache that others are already shipping so I don't think a reference implementation is the solution. I think the problem is motivation - are there any use cases that adding DataCache enables that couldn't otherwise be implemented with what we already have and are those compelling enough to complicate the platform with another cache mechanism. Further, would we end up with conflicts between the AppCache and the DataCache since they're currently not unified as far as I can tell.
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What I'm asking for is a more unified proposal that says "If you have already implemented AppCache, here's what you add to make the same cache provide the additional functionality needed to enable these additional use cases." This will inevitably be a compromise from what a pure implementation looks like (your current DataCache spec, say) but lots of the web is necessarily a compromise because it builds on prior art that might not have been ideal but has been specified, built and deployed (and not always in that order).
This is pretty close to my own point of view. I think the functionality offered by DataCache is interesting, but I'd be much more interested in putting it into Safari and WebKit if it was exposed as a set of extra AppCache features, rather than a competing and unintegrated separate model.
I believe AppCache can reasonably be extended to support the extra functionality of DataCache. For example, it should be possible extend the manifest format with a way to express that a certain URI should be served by script, and to give that script access to a static cached copy if it chooses to use it.
This would allow people to form a judgement about whether the additional use cases are worth the additional effort instead of whether the additional use cases are worth yet another cache. I think the ship has already sailed on AppCache and we can't undo that even if we wanted to and I don't think a competing solution is the right approach.
I agree with this as well. I think extending AppCache is likely to be a more successful approach than building a full alternative. I will go further and say that if some of the advanced DataCache features were expressed as extensions AppCache, we would likely be very interested in implementing them.
Regards, Maciej
