[whatwg] Offline Web Applications feedback

Maciej Stachowiak mjs at apple.com
Wed Aug 6 02:20:32 PDT 2008

On Aug 5, 2008, at 11:30 PM, Aaron Boodman wrote:

> Some quick notes/questions...
> - I think the manifest should be some structured, extensible format
> such as XML or JSON. The current text-based format is going to quickly
> turn into a mess as we add additional fields and rows.

We've implemented the current format already in WebKit (available in  
nightlies and the Safari 4 Developer Preview).

The format does not seem to have much call for extension and seems  
easy to understand and use as-is.

> - I like the fallback entry feature, but I don't understand why it is
> coupled to opportunistic caching. On the Gears team, we frequently get
> requests to add a feature where a certain pattern of URLs will try to
> go the network first, and if that fails, will fall through to a
> certain cached fallback URL. But nobody has asked for a way to lazily
> cache URLs matching a certain pattern. Even if they had, I don't
> understand what that has to do with the fallback behavior. Can we
> split these apart, and maybe just remove the opportunistic caching
> thing entirely?

I think the idea of opportunistic caching (as I understand it) is that  
the author can be lazy, and not write a manifest at all.

> - It seems odd that you request a resource and the server returns 400
> (bad request) we fallback. Maybe it should just be up to the server to
> return an error message that directs the user to the fallback URL? I'm
> not sure about this one, looking for feedback.
> - Maybe this is obvious, but it's not specified what happens when the
> server returns a redirect for a resource that is being cached. Do we
> cache the redirect chain and replay it?
> - In practice, I expect the number of URLs in the online whitelist is
> going to be unbounded because of querystrings. I think if this is
> going to exist, it has to be a pattern.

I agree the online whitelist should allow patterns of some form.

> - I know you added the behavior of failing loads when a URL is not in
> the manifest based on something I said, but now that I read it, it
> feels a bit draconian. I wish that developers could somehow easily
> control the space of URLs they expect to be online as well as the ones
> they expect to be offline. But maybe we should just remove the whole
> thing about failing loads of resources not in the manifest and online
> whitelist for v1.

I think it would be hard to add later after the fact.


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