Eric Bohlman ebohlman at
Thu Jun 24 20:30:50 BST 1999

On Thu, 24 Jun 1999, Richard Tobin wrote:

> > That *is* supposed to be a rule: that you can GET the same URL
> > as many times as you want with no changes.  Otherwise caching
> > would not work.
> Surely the whole mechanism of HTTP "if-modified-since" and "expires"
> headers exists because this is not true?

"With no changes" means "with no changes occurring as a *result* of
GETting the URL.  i.e. given a sequence of N>=1 GETs G1,...,Gn to the same
URL with Gn taking place at time Tf, the result of Gn depends only on Tf
and *not* on N.

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