Re: Clarification on cacheability

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Josh Cohen:
>
[...]
>I guess if there is any chance that the response could be different,
>based on client auth, client type, or whatever, then it is not safe to
>cache. 

It _is_ safe to make the response cacheable as long as you use Vary
correctly, this is what Vary was invented for.

>(especially since caches dont filter based on accept before
>returning responses)

As Roy said, most (all?) 1.1 caches don't actually implement the
refined filtering made possible by Vary.  They implement the Vary
requirements in 1.1 by treating 'Vary: anything' as equivalent to
'no-cache'.

But you can still use Vary if you want to help possible future caches:
I would consider this to be good protocol design.  You can find some
examples of the use of Vary+Expires in RFC2295.


Koen.

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