[Jax.PM] Re: perl HTTP header insertion proxy

[Nate Campi]

On Thu, May 15, 2003 at 12:16:34AM -0400, WC -Sx- Jones wrote:
> [a jax.PM member posting]
> OK, now I am prolly totally brain dead  =)
> 
> 'Expires' is a function of the proxy'ing server itself (mod_proxy.)  
> How about fixing SSI server to use:

Only the origin can and should dictate when content expires.

> Are you using the Apache Server Admin Handbook written by Kabir?  It 
> pretty much describes what you stated in the first posting; but it 
> never mentions that SSI output is unusable by a proxy.  I would think 
> that would be a major issue - one I feel he would have noted - unless 
> the caching server doesn't recognize the proxy server to start with.  
> In other words - is the SSI server a proxy server too?

If this handbook leaves this out, I question it's quality. As for your
question, no the SSI server generates and serves content and is not any
kind of proxy.

The mod_perl site talks in many places about headers needed for caching:
http://perl.apache.org/docs/general/correct_headers/correct_headers.html#Why_Headers

SSI can not and will not set the Last-Modified since many pages go into
making one URL, it also cannot set Content-Length since it can't stat a
single file.

There are various ways to get SSI-based site to cache, a good one being
the XBitHack, but we generate pages with third partry software that
cannot set the executable bit. See:
http://www.bowiesnyder.com/writings/caching_shtml.htm

I cannot crawl the filesystem to add the executable bit since I have at
least a million files in my docroot.

Apache 2.0 should be able to work with directives to ignore missing
content-length headers, but long story short it doesn't. Apache 1.3
mod_proxy needs headers that aren't there and that the origin server(s)
cannot feasibly add. A proxy is the simplest link to add to this chain.
Anything else either adds too much complexity or simply isn't worth the
effort. A proxy is simple and easy to simply turn off if you have
trouble with it.

I know you know Apache well Bill, but I've done my homework.
-- 
Nate Campi    http://www.campin.net