[Koha-bugs] [Bug 1373] Please send no-cache headers

[bugzilla-daemon at pippin.metavore.com]

http://bugs.koha.org/cgi-bin/bugzilla/show_bug.cgi?id=1373





------- Comment #3 from devin at freeshell.org  2007-10-05 06:33 -------
This is repeatable, yes.  No, there is no special case; it's all pages.  If you
don't send cache-control directives then all returned pages MAY be cached. 
Just because your browser is liberal with refreshes and mine is less, doesn't
mean that my browser is wrong.  Read the HTTP spec and you'll see that you MUST
send cache-control headers.

Do not make it a syspref! To send back user-specific pages without specifying
that they shouldn't be publically cached is wrong!  And I don't mean to use
Expires. Of course, most images should be sent with cache-control set to cache
them publically.

See HTTP 13.1.1: Cache Correctness

A correct cache must respond to a request with the most up-to-date response
held by the cache that is appropriate to the request (see Sections 13.2.5,
13.2.6, and 13.12) which meets one of the following conditions:

* It is "fresh enough" (see Section 13.2). In the default case, this means it
meets the least restrictive freshness requirement of the client, origin server,
and cache (see Section 14.9); if the origin server so specifies, it is the
freshness requirement of the origin server alone. If a stored response is not
"fresh enough" by the most restrictive freshness requirement of both the client
and the origin server, in carefully considered circumstances the cache may
still return the response with the appropriate Warning header (see Section
13.1.5 and 14.46), unless such a response is prohibited (e.g., by a "no-store"
cache-directive, or by a "no-cache" cache-request-directive; see Section 14.9


See also section 13.4:

Unless specifically constrained by a cache-control (Section 14.9) directive, a
caching system may always store a successful response (see Section 13.8) as a
cache entry, may return it without validation if it is fresh, and may return it
after successful validation. If there is neither a cache validator nor an
explicit expiration time associated with a response, we do not expect it to be
cached, but certain caches may violate this expectation (for example, when
little or no network connectivity is available). A client can usually detect
that such a response was taken from a cache by comparing the Date header to the
current time.




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