- From: Jim Gettys <jg@pa.dec.com>
- Date: 1998年11月11日 11:18:50 -0800
- To: Jeffrey Mogul <mogul@pa.dec.com>
- Cc: Chris DiPierro <cdipierr@us.ibm.com>, http-wg@hplb.hpl.hp.com
- Message-Id: <9811111918.AA03187@pachyderm.pa.dec.com>
> From: Jeffrey Mogul <mogul@pa.dec.com> > Resent-From: http-wg@hplb.hpl.hp.com > Date: Tue, 29 Sep 98 15:29:53 MDT > To: Chris DiPierro <cdipierr@us.ibm.com> > Cc: http-wg@hplb.hpl.hp.com > Subject: Re: 200 Level warnings in revalidation > ----- > Chris DiPierro <cdipierr@us.ibm.com> writes: > > The spec says that all 200 level warnings must be retained after a > successful revalidation. > > However, it also says that all end-to-end headers (Warnings are > end-to-end) must be replaced after by the corresponding end-to-end > header in a revalidation. > > So if we had a cached copy of an entity that has a 200 level > warning associated with it and when we revalidate, we get a Warning > header w/o the 200 level warning, are we supposed to keep it or > not? > > I believe you are referring to section 13.5.3 (Combining Headers), > and this particular passage: > > The end-to-end headers stored in the cache entry are used for the > constructed response, except that > > . any stored Warning headers with warn-code 1xx (see section > 14.46) MUST be deleted from the cache entry and the forwarded > response. > . any stored Warning headers with warn-code 2xx MUST be retained > in the cache entry and the forwarded response. > . any end-to-end headers provided in the 304 or 206 response MUST > replace the corresponding headers from the cache entry. > > Unless the cache decides to remove the cache entry, it MUST also > replace the end-to-end headers stored with the cache entry with > corresponding headers received in the incoming response. > > In other words, the set of end-to-end headers received in the > incoming response overrides all corresponding end-to-end headers > stored with the cache entry (except for stored Warning headers with > warn-code 1xx, which are deleted even if not overridden). > > I guess this might be somewhat confusing. The second exception > in the bulleted list: > > . any stored Warning headers with warn-code 2xx MUST be retained > in the cache entry and the forwarded response. > > appears to conflict with > > Unless the cache decides to remove the cache entry, it MUST also > replace the end-to-end headers stored with the cache entry with > corresponding headers received in the incoming response. > > but the obvious resolution is that special treatment for Warning > headers applies to this paragraph, as well as the one above the > list of exceptions. I.e., the paragraph should read: > > Unless the cache decides to remove the cache entry, it MUST also > replace the end-to-end headers stored with the cache entry with > corresponding headers received in the incoming response, except > for Warning headers as described immediately above. > > -Jeff I plan to adopt Jeff's version of the paragraph. - Jim
Received on Wednesday, 11 November 1998 11:22:35 UTC