Re: HTTP HEAD requests for Last-Modified info

• To: marc@ckm.ucsf.edu
• Subject: Re: HTTP HEAD requests for Last-Modified info
• From: Larry Masinter <masinter@parc.xerox.com>
• Date: Thu, 20 Jun 1996 11:38:04 PDT
• Cc: www-talk@w3.org
• Fake-Sender: masinter@parc.xerox.com
• From masinter@parc.xerox.com Thu Jun 20 15: 27:59 1996
• In-Reply-To: "Marc Salomon"'s message of Thu, 20 Jun 1996 10:30:10 PDT <9606201030.ZM7466@home.ckm.ucsf.edu>
• Message-Id: <96Jun20.113804pdt."2763"@golden.parc.xerox.com>
• Sender: Larry Masinter <masinter@parc.xerox.com>
• X-List-URL: http://www.w3.org/pub/WWW/Archives/Public/www-talk/

> Caching can't function to its potential if servers don't advertise L-M whenever
> possible.  Caching is essential to HTTP scalability in the near-term.  Server
> authors: N.B. above.

Actually, caching can work without Last-Modified, as long as the
origin server sends Expires and an ETag.

Expires is actually what lets a cache do its work: give the cache
permission to hold on to something. And the ETag lets the cache use
If-None-Match instead of If-Modified-Since with date stamps, since
dates are unreliable in some systems which might otherwise be able to
use cache validators.

Larry

• Re: HTTP HEAD requests for Last-Modified info
• From: "Marc Salomon" <marc@ckm.ucsf.edu>

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