Re: Re caching of frequently used pages

Guenther Fischer (
Wed, 15 Dec 1993 18:43:48 +0100 (MET)

> 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