Re: HTTP Caching Model?

In message <199412160001.QAA09663@neon.mcom.com>, Ari Luotonen writes:
>
>> Why is that such a bad thing? The server can give a lot of information
>> about what's available by giving several URI: headers.
>
>Hmmm, I don't necessarily support this -- this wastes bandwidth.

I agree. But I didn't say the server should or must; just that it may.

The only thing that it _must_ do is issue _some_ URI: header with 
a vary parameter if it's got variants. That's enough to prevent
proxies from jumping to conclusions.

>Besides, the set of available versions may vary, so the proxy can
>never be sure if it has all the presentations/knowledge of them
>without going to the original server.

If the server gives an Expires: header, the proxy can conclude that
the variants are stable until then. Otherwise, the usual hueristics
apply.

See:
	http://www.hal.com/%7Econnolly/drafts/formalism.html

for details.

Dan