Re: i37 - Vary and non-existant headers

Henrik Nordstrom wrote:
> Vary and the cache rules around Vary do not care about semantics of
> headers. Just their existence and value.  Vary is a selector telling
> caches which headers of the request need to be included in the
> comparison when comparing two requests. 
> 
> The logic actually selecting the correct variant depending on the
> request content is all deferred to the web server, except when there is
> exact matches filtered by Vary.
  ^^^^^

What about whitespace differences (e.g. leading/trailing whitespace,
whitespace following the header name colon), multi-line breaks, and
multiple occurrences of the same header?

Does exact means _exactly_ in all those respects, or is it acceptable
for a cache to canonicalise certain things, like converting multiple
occurences of a header to a single header by joining with ", " (or
","), converting multi-line headers to single-line, and stripping
leading/trailing whitespace from the header value?

Thanks,
-- Jamie