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Re: caching CGI responses

From: Ho John Lee <hjl@hplb.hpl.hp.com>
Date: Thu, 05 Dec 1996 23:45:28 PST
Message-Id: <199612060745.AA091228328@hplight.hpl.hp.com>
To: mogul@pa.dec.com
Cc: http-wg%cuckoo.hpl.hp.com@hplb.hpl.hp.com
> However, I think everyone agrees with you that it's both possible and
> desirable for origin servers to explictly mark all responses
> as either non-cachable or cachable, since then the proxies don't
> have to play guessing games based on the URL.  E.g., if you are
> writing a server that uses CGI or "?" URLs, and you know that
> some of these are cachable, if you simply add a Last-Modified
> or Expires (in the future) header to the response, then a well
> designed proxy will cache the response.  Conversely, if you
> mark the response as Expires "in the past", then no well designed
> cache should cache it (without at least sending you a conditional
> GET to see if the value has changed).

Do you know offhand which proxies currently interpret the
Last-Modified header in a way that would cache CGI/"?" URLs?

The interactive imaging protocol we're currently developing
*should* be cacheable, as the image tiles being sent don't
change, and the initial image view will generally be the same
each time it's requested. It would be nice if we could get
*some* systems to cache something while we work out a better
scheme for making the rest of the tile information cacheable
by proxies.

--hjl
Received on Thursday, 5 December 1996 23:53:09 EST

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