Re: cache-busting and charsets again

Roy T. Fielding:
>
[...]
>In any case, it is rare for agent profiles to differ much behind a
>shared cache during the lifetime of a cached response.

We would hope so, because this would mean that a HTTP/1.1 Vary would be
able to save round trips often.  

However, I do not believe that differing profiles are that rare in
practice.  They are very common behind the shared cache of the cern.ch
domain I am currently using.  And one would expect even bigger
diversity behind a country-level cache.

>Using multiple URLs is advantageous because it gives the user agent more
>information, and thus more control over how it completes the retrieval,
>and also improves load-sharing and mirroring techniques and reduces the
>amount of information the client has to send to the server on every
>request. 

I'm confused.  Are you talking about the long-term advantages of
multiple URLs here?  I don't see how you would get these advantages
using the current generation of software.

> Using a single URL is advantageous because it only requires
>one round-trip, assuming the server guesses right.
>
>....Roy

Koen.