Re: What is The logic of Vary Headers cachiness?

tor 2013-07-25 klockan 23:37 +0300 skrev Eliezer Croitoru:

> The main problem with ETAG from what I have seen and I need to read more
> about ETAG, is..
> couple mirrors ETAG should be the same for all servers objects in the
> level of HASH like.. which is not.. an example:

ETag uniqueness is only required per URL, not per application level
object.

Having syncronized ETag values across mirrors is desireable and would
simplify manaement of mirrored content in both caches and applications,
but is not required by RFC2616.

Extending HTTP with ETag values crossing mirrors is relatively easy in
terms of specification, but halts on technical grounds on having it
implemented.

Content-MD5 and specifically Digest headers can address this, but is
both lacking in conditional processing capabilities.

Note: Content-MD5 have been deprecated as there is some ambigouity on
what it really means, plus is limited to MD5 only.

> So even the content type is not the same...

Which means some mirror admin needs to be poked a bit..

> they both run apache both
> run 2.2.22 and they both have right LM headers but they both have
> different ETAG which is a bit weird but not unacceptable..

To HTTP it is fully acceptable. The two are completely different URLs.

The fact that they happen to be mirrors is application layer defined,
outside the protocol. As far as HTTP is concerned they are separate
rsources.

> I do hope and know that httpbits tries to make all of the above
> true.(reading)

httpbis do not address mirrors.

Regards
Henrik
Received on Fri Jul 26 2013 - 11:02:40 MDT