- From: Jim Seidman <jim@spyglass.com>
- Date: Mon, 14 Aug 95 09:40:35 -0500
- To: dmk@allegra.att.com (Dave Kristol)
- Cc: www-talk@www10.w3.org, http-wg@cuckoo.hpl.hp.com
At 05:48 PM 8/10/95 EDT, Dave Kristol writes: >I have assumed (erroneously?) that a caching proxy must send >conditional GETs to the origin server. If so, there's already the cost >of a connection. The State-Info (previously "Session-ID") can ride the >request almost for free. This isn't necessarily true. If the server sends "Expires" headers, then the proxy can pretty safely avoid sending if-modified-since requests, for example. Even without "Expires" headers, some caching proxies just use simple algorithms to avoid doing a GET on each request, e.g. only re-requesting text/* files if they're at least an hour old. This applies not only to proxies, but also to clients with persistent caches such, if I have a document still cached on my hard-drive from an access yesterday. Given these considerations, and the slowly increasing use of "Expires" headers, State-Info could be expensive indeed. -- Jim Seidman, Senior Software Engineer Spyglass Inc., 1230 E. Diehl Road, Naperville IL 60563
Received on Monday, 14 August 1995 10:40:49 UTC