On Unix, I normally deploy nginx in front of Varnish in front of my application server. Both nginx and Varnish are acting as reverse proxies here. Varnish maintains a cache and supports things like If-Modified-Since, Cache-Control response headers and PURGE requests from the application. nginx is good at receiving a lot of connections. I also use it to serve some static content, enable gzip compression etc.
On Windows, I can manage with Squid in front of IIS. I'm planning to deploy my (Python) application as an ISAPI wildcard filter (using the isapi-wsgi package), so the application will live in a thread pool managed by IIS.
However, Squid development on Windows appears to have stalled, and I'd prefer to keep IIS on port 80, so that I can serve certain things directly from disk. I also suspect IIS is more resilient in handling lots of connections than Squid on Windows.
What do people normally use here? One option would be to use another free-standing caching proxy in front of IIS. Another option may be something installed as an ISAPI filter, which would intercept requests and respond to things like If-Modified-Since, requets for images and other cached resources, and PURGE requests from the application.
Does such a thing exist? Or are the only real choices Squid and MS ISA (too expensive).
Cheers, Martin