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Re: cache-busting document

From: Ben Laurie <ben@gonzo.ben.algroup.co.uk>
Date: Sat, 7 Jun 1997 17:46:58 +0100 (BST)
To: Larry Masinter <masinter@parc.xerox.com>
Cc: martin@mrrl.lut.ac.uk, http-wg@cuckoo.hpl.hp.com, ircache@nlanr.net
Message-Id: <9706071746.aa29006@gonzo.ben.algroup.co.uk>
Larry Masinter wrote:
> I've not seen any studies or reports that document the effect
> on effectiveness of caching for the HTTP/1.1 features that
> were added to support caching. Documenting the results would
> be very useful. It would be my guess that, after such documentation,
> you'd have more specific advice than 'use HTTP/1.1'.

Has anyone actually implemented an HTTP/1.1 cache yet? Certainly, Apache's
isn't. Sigh.

> 
> >  Use the Expires header on documents and images where feasible
> >     - this will help caches to decide when your objects are stale.
> 
> When is it feasible and when is it not? While we've conjectured
> the applications of Expires for sites that do dynamic content
> generation from static sources, for example, is that actually
> feasible?

Apache provides the facility (mod_expires).

> Do sites with planned expiration set expires dates?

Good question - this implies a level of planning I expect is largely absent
from the Web.

> Is it feasible to, for example, declare that '/images' at a site
> never changes (if you need to modify an image, give it
> a new name and change all the references), and then set it
> so that the embedded images never expire from caches even if
> the documents are dynamic?

Now this is a stunningly sensible suggestion. Changing all the references
would be onerous, though - unless it was done by server-side parsing (yech).

Cheers,

Ben.

-- 
Ben Laurie                Phone: +44 (181) 994 6435  Email: ben@algroup.co.uk
Freelance Consultant and  Fax:   +44 (181) 994 6472
Technical Director        URL: http://www.algroup.co.uk/Apache-SSL
A.L. Digital Ltd,         Apache Group member (http://www.apache.org)
London, England.          Apache-SSL author
Received on Saturday, 7 June 1997 10:02:16 EDT

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