[racket] Serving static content

What Jay said.  If you want to keep things simpler, and are only going 
to have a few simultaneous requests at a time, you can have Racket serve 
all the HTTP directly.  But I almost always decide an obvious first 
thing to do is to push off static file serving to Apache (or nginx, or 
lighttpd), before I even test performance.  You can feed to Racket 
process using HTTP proxying or my old SCGI library.  Separating static 
from dynamic also makes sense for CDN reasons.

Also, besides possible performance reasons, there's a good chance an 
application is going to want to use HTTPS at some point.  The SSL 
implementations tend to be buggy[*], and you probably don't want native 
library code in the same process space as your Racket VM unnecessarily.  
Imagine an intermittent Linux process crash failure in your deployed 
system, and how glorious it would be for your debugging if it were 
Apache crashing rather than Racket.  I'm happy to report that Racket 
doesn't crash on my servers (except for, years ago, OOM due to some 
memory-voracious application code written by a non-CS person).

Also, if you're doing applications deployed as intranet ones for 
different organizations, sometimes you'll need to do unusual SSO 
authentication, and it's nice when you can just use the same Apache 
module that they use.  (I've implemented at least half a dozen different 
authentication protocols in pure Racket, and Racket is definitely up to 
the software part of the problem, but you probably don't want to be in 
the business of understanding+implementing+supporting some other 
vendor's or IT group's unique SSO setup.  I'd have to do that even more, 
if I couldn't dump a lot of the more standard SSO setups on Apache modules.)

[*] Witness yesterday's yet-another-Debian-security-update of OpenSSL, 
with another 6 CVEs, because very few people write perfect code in C, 
and SSL-related protocols tend to be hairy.  If some ambitious student 
wants a fun summer project, try implementing an SSL stack in pure Racket.

Neil V.