[whatwg] Offline Web Apps

[Ian Hickson]

On Thu, 11 Oct 2007, Robert O'Callahan wrote:
> >
> > > -- Several Web app authors have asked for the ability to test 
> > > whether a resource is cached, for their online apps. For example, 
> > > when you're zooming in and out of a map, the application could 
> > > choose which tile(s) to use for the animation by scaling them up or 
> > > down. This would also be convenient for offline use, where a 
> > > resource might not necessarily be in the offline cache but you could 
> > > use it if it happened to be available.
> >
> > Interesting. This isn't covered yet, should we add it immediately?
> 
> I think it should be added *somewhere*, but it doesn't have to be part 
> of the offline spec itself (although it is particularly useful when 
> you're offline).

The problem with isLocallyAvailable() -- as noted by Maciej on IRC -- is 
mostly one of race conditions. What if the resource was removed in between 
you asking for it and using it? Or added? Or what if you go offline (thus 
changing the rules) in between checking for and using the resource?

I'm going to punt on this for now, pending implementation and author 
experience. I'm certainly open to suggestions though.

-- 
Ian Hickson               U+1047E                )\._.,--....,'``.    fL
http://ln.hixie.ch/       U+263A                /,   _.. \   _\  ;`._ ,.
Things that are impossible just take longer.   `._.-(,_..'--(,_..'`-.;.'