Re: Last-Modified vs. Expires

hno@hem.passagen.se writes:

>Well... this should of course be combined with a walid Expires: header
>set something reasonable wrt to the content... we do not want objects
>that never ever can be updated do we?

I think we do. I think there are a significant number of objects
out there which never change: cartoons (Dilbert), mailing list archive
messages, software distribution files, my home page.

Have you seen the Mars Pathfinder home page? http://mpfwww.jpl.nasa.gov/
There are quite a few mirror sites. Why do we need so many mirror
sites when we have all this wonderful caching technology?

Lets assume that there were a single Mars Pathfinder web site and
all the world accessed it throught web caches. Would it have worked?
I think it would NOT work because with 'no-cache' and IMS, you still
have a very large percent of requests going all the way to the
origin for validation.

I think it would work if the protocol could allow the caches
to realize that the images (and maybe some of the HTML) only needed
to be transferred ONCE. New content would be added under uniuqe URLs.

I also think this is one reason why USENET works pretty well.
Articles are only transferred once. You can't do an IMS GET
or a reload for a usenet article.

Duane W.
Received on Tue Jul 29 2003 - 13:15:42 MDT