[Zope] Caching/http-acceleration and proxying Zope-served content

sean.upton@uniontrib.com sean.upton@uniontrib.com
Mon, 08 Jan 2001 12:50:29 -0800


I have a question, for anyone experienced in working with Zope and caching
proxies:

I'm setting up a load-balanced server farm that has nodes that will run
Apache and proxy (via mod_proxy) to ZEO clients running ZServer.  This farm
is routed (both ways) through a layer 4 load-balancing appliance, and all
these boxes (both nodes and the balancer) are sitting inside a DMZ with
private IP addresses.  The public world will access these servers via a
firewall box running transparent proxy (actually, I guess, similar to
squid's http_accel mode; the semantics here are a bit tricky, as it's more
of a inverse trans-proxy).  Between Apache and Zope, there would be several
virtual hosts, and I'd be using the SiteAccess product.  It gets a bit
tricky in that I need to access several different virtual hosts inside the
DMZ (one for the ZEO farm, and another for a dedicated CGI-based ad server
on another box) via the proxy.  A more detailed (ascii art) diagram of what
I am trying to do, is at http://209.132.8.98/server_ascii_art.txt

My question is this: does anybody have any thoughts on the merits of Squid
(http accelerator mode) versus Apache/mod_proxy in terms of caching, virtual
hosts, and the like when working with Zope sites?  Any big pitfalls to this
kind of setup with Zope sites?

Also, somewhat related, is: if anybody knows if Squid can even handle
multiple virtual hosts running on different boxes?  Or is squid not suitable
for an inverse-proxy running on the border of a DMZ containing more that a
single host?

I'd really appreciate anyone's thoughts.  Once I get this thing working,
I'll likely end up writing a howto regarding how I did it, as this seems
like a useful setup for a high-volume, heterogeneous (not ideal, but
reality), production media site running Zope (and other legacy CGI apps /
static content as well)...

Much thanks in advance,
Sean

=========================
Sean Upton
Senior Programmer/Analyst
SignOnSanDiego.com
The San Diego Union-Tribune
619.718.5241
sean.upton@uniontrib.com
=========================