On 12/8/06, Henrik Nordstrom <[EMAIL PROTECTED]> wrote:
A strong ETag must be unique among all variants of a given URI, that is
all different forms of entities that may reside under the URI and all
their past and future versions.
A weak ETag may be shared by two variants/versions if and only if they
can be considered semantically equivalent and mutually exchangeable at
the HTTP level with no semantic loss. For example different levels of
compression, or minor changes of negligible or no importance to the
semantics of the resource (hit counter example in the specs).
I think we all (hopefully) agree that a weak ETag is ideally what
mod_deflate should add. But, the specs simply dropped the ball here
as doing that breaks conditional requests. If we could issue a weak
ETag and have it work for conditional requests, this would be easy and
be done by now.
We can't, so I would much prefer that we don't break conditional
requests just because mod_deflate is in use. I also don't believe we
can come up with a reversible ETag semantic without rewriting big
chunks of code or introducing butt-ugly hacks. Apache has always
treated the ETag as opaque (except for "W/") - to do otherwise is to
bust large assumptions. -- justin
