Re: Re caching of frequently used pages (Guenther Fischer)
From: (Guenther Fischer)
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Subject: Re: Re caching of frequently used pages
Date: Wed, 15 Dec 1993 18:43:48 +0100 (MET)
In-reply-to: <> from "" at Dec 15, 93 03:01:00 pm
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> E-mail from: Prof J Larmouth              J.Larmouth @ ITI.SALFORD.AC.UK
> Subject:      Re caching of frequently used pages
> ...

> Of course,  any greater use of caching must raise the issue of an
> "expected frequency of update" value to be held with each document,  in
> order to assist the LAN-cache server in knowing how long to keep things.

I have an experimental cache server running based on Tony Sanders Plexus.
Users are connected per default to this server through the
WWW_http_GATEWAY environment variable for Mosaic (Unix). Mosaic for Windows
and Lynx will follow. (I hope soon ... - we need it).

setenv WWW_http_GAETWAY

Then Mosaic gives all http://host:port/... URL to 
in the form

GET /host:port/...

The main base of "my" caching is:
- Server is HTTP/1.0 and
- has the Last-Modified (L-M) value in its header.
- do not handle queries
- run as a simple gateway for servers not to cache

I can configure the cache server:
- list of servers to cache
- TIME_SHORT for html/text
- TIME_LONG for other (gifs etc.)

Algorithm implemented at now:

- If request not in cache: get it -> give it to client and cache
  (I store it with full header)
- If request in cache:
  - if NOW - cache files TIME < TIME_SHORT
      put it to client 
      put it to client      and
      get the head from the server
      if L-M of cache == L-M from server
         utime the cache file to now
         unlink the file and get it

For TIME_LONG files in the same manner.

I've also started a students work to clean and refresh the cache
without client (at night or weekend).

You can try my cache server: and are on the list.

Name:      Guenther Fischer
Institute: TU Chemnitz, Universitaetsrechenzentrum
Phone:     0371 668 361