[Http-crcsync] General comments on crcsync document

[Patrick McManus]

On Thu, 2009-07-09 at 21:48 +0200, Alex Wulms wrote:
> Hi,
> 
> Regarding caching: I'll read-up on the vary part again. Does it work for a 
> combination of request and response? The important point being that the 
> response is only valid for a request with the matching block-headers.

yes.. it does exactly that.

"Vary: If-Block" means that the response varies based on the value of
the request header If-Block (which in turn limits cachability of that
response to other requests with the same if-block header).

I've seen caching proxies that basically say "whoa, too complicated" and
treat that as meaning "Cache-Control: no-cache", but they don't all do
that and it leaves room for good implementations. And in the case of
deltas it is not hard to imagine cache hits in such a scenario.