W3C home > Mailing lists > Public > ietf-http-wg@w3.org > April to June 2009

Re: httpbis-p6-cache-06 and no-store response directive

From: Jamie Lokier <jamie@shareable.org>
Date: Wed, 24 Jun 2009 21:41:40 +0100
To: Henrik Nordstrom <henrik@henriknordstrom.net>
Cc: yngve@opera.com, Mark Nottingham <mnot@mnot.net>, "ietf-http-wg@w3.org" <ietf-http-wg@w3.org>
Message-ID: <20090624204140.GX14121@shareable.org>
Henrik Nordstrom wrote:
> mån 2009-06-15 klockan 16:42 +0200 skrev Yngve Nysaeter Pettersen:
> 
> > As I said above: If they made the choice. In many cases I don't think they  
> > did more than select a development environment that made the choice for  
> > them, based on what is supposed to provide a "revalidate each time the  
> > user clicks on a link to this document"-functionality, that is, the same  
> > as "Cache-Control: max-age=0" and "no-cache".
> 
> All environments I have seen support setting these kind of things if you
> care about them, and emit a default "do not cahe this response" header
> if the author / site developer using such environment don't care. Most
> people who don't care simply do not know, and quite happily try to
> accomodate for caching when they learn what it is.
> 
> Blaiming the dev environment for emitting a safe low-performance default
> cache profile won't get us very far, neither is trying to work around
> this in the cache layer. This situation will persist, and any changes we
> make to the protocol will only get reflected in those dev environments
> using the new names, until the content/site developers gets their acts
> together.

Absolutely.

I think the main reason I've seen for dev environments disabling HTTP
caching is that occasionally, a developer changes the underlying files
which make up a site, and if caching is enabled, stale pages show in
the browser sometimes which is a _very_ annoying time sink when it's
not expected.

The performance advantage from caching is just not worth the confusion
from accidental stale pages.

This may sound stupid, but you can tell it's important from the
significant number of web pages explaining how to disable HTTP caching
really really thoroughly on all clients and proxies.  (Cache-Control:
no-cache,no-store,max-age=0; Pragma: no-cache; something like that.)

Even I found, in some tests recently with Apache and Firefox that I
was surprised to see the "Reload" button not showing up to date
changes after I'd edited files on the server...  I'd forgotten about
"Shift+Reload" being needed in Firefox.  It was a default Apache
configuration, and that isn't good enough...

-- Jamie
Received on Wednesday, 24 June 2009 20:42:18 GMT

This archive was generated by hypermail 2.2.0+W3C-0.50 : Friday, 27 April 2012 06:51:04 GMT