I have to work in a traditional (i.e., fork/exec) CGI environment.  I
would like to use WEBRick because it supports servlets (which is
something I understand).

Is there a way to use the WEBRick servlet stuff inside a CGI
environment?  This seems like a reasonable thing to do, but everything
I read on WEBRick starts with the WEBRick HTTP server.  I would like to
use it from the servlet environment down.  I'd also like to be able to
move back and forth between CGI and FastCGI, if possible.

Also, I would like to know where to look for any sort of web framework
that works inside traditional CGI (it would be cool, of course, if it
also worked in FastCGI with no changes).  Is WEBRick the best choice?
What does Rails use (I understand it runs under FastCGI)?

Thanks for any help or guidance.

--Kevin