[whatwg] AppCache-related e-mails

[Bjartur Thorlacius]

Ask HTTP implementors to store a potentially stale fallback copy for
offline use when an authoritative copy is unavailable. Even HTTP
caches are allowed to return stale responses as long as they warn
their clients (so they can warn their clients or fetch an
authoritative copy via another route).
Browsers should keep copies of the most used entries for offline use.
It's probably a matter of minor tweaking, considering that mainstream
browsers support offline modes already.

>From http://www.w3.org/Protocols/rfc2616/rfc2616-sec13.html#sec13.1.5:
In some cases, the operator of a cache MAY choose to configure it to
return stale responses even when not requested by clients. This
decision ought not be made lightly, but may be necessary for reasons
of availability or performance, especially when the cache is poorly
connected to the origin server. Whenever a cache returns a stale
response, it MUST mark it as such (using a Warning header) enabling
the client software to alert the user that there might be a potential
problem.

P.S. Your hypothetical major overhaul should probably involve
splitting the dynamic content into separate resources linked to from a
static main page/index using iframes.