Re: [PATCH] error responses have wrong headers (part 2)

["Roy T. Fielding" <fi...@kiwi.ICS.UCI.EDU>]

>> removes a bit of code which is never executed due to r->no_cache never
>> being set when (r->proto_num >= 1001).
>
>I don't think this should be removed. r->no_cache is part of the
>Apache API, mod_negotiation isn't the only module that's allowed to
>set it. Just because mod_neg never sets it for HTTP/1.1+ requests
>doesn't mean that some other module won't, and if it does, then we
>need the Cache-Control: private to be sent, because that would then be
>the correct behavior.

No, we don't, because Cache-Control: private is not the right thing
to send even if r->no_cache is set.  r->no_cache was a temporary hack
that is obsoleted by Vary.  In order to be HTTP/1.1 compliant, such a
module MUST output a correct Vary header field; if it doesn't want to
be HTTP/1.1 compliant, then the Expires field is sufficient.

....Roy

Re: [PATCH] error responses have wrong headers (part 2)

[Alexei Kosut <ak...@nueva.pvt.k12.ca.us>]

On Thu, 8 May 1997, Roy T. Fielding wrote:

> No, we don't, because Cache-Control: private is not the right thing
> to send even if r->no_cache is set.  r->no_cache was a temporary hack
> that is obsoleted by Vary.  In order to be HTTP/1.1 compliant, such a
> module MUST output a correct Vary header field; if it doesn't want to
> be HTTP/1.1 compliant, then the Expires field is sufficient.

No, wait... r->no_cache has always had the implied meaning of "don't
let proxies cache this, because it's only for the browser that made
the request." It is true with HTTP/1.1, mod_neg can use Vary: instead,
to do what it needs to; and it does. And I agree that in most cases,
an appropriate Vary header would be the thing to do.

However, there are other instances where r->no_cache might be set, and
where Cache-Control: private would be the appropriate response. And
the current code would seem to me to be the correct thing for the
server to do.

-- 
________________________________________________________________________
Alexei Kosut <ak...@nueva.pvt.k12.ca.us>      The Apache HTTP Server
URL: http://www.nueva.pvt.k12.ca.us/~akosut/   http://www.apache.org/