Implementig a XCAP web server: Ebb and Rack?

Hi, I plan to deploy a web server to implement a XCAP service (it’s
basically
a web server which handles body with specific XML content). Some
examples:

  • The client requests a XML document (GET) so the server replies it in
    the
    body of the 200 OK.

  • The client stores a XML document (PUT) in the server, so the server
    validates it and stores in a DB table.

There are a lot of web servers built in Ruby and I’m getting a bit crazy
by
tryting to choose one. I’ve read about Ebb web server (which seems to be
very
fast) and RACK (which seems to be a framework to build the application
by
receiving requests from the web service, Ebb in this case).

Unfortunatelly, by reading the doc of RACK (Ebb has no doc at all) I
can’t
figure how to build the application:
http://rack.rubyforge.org/doc/

RACK doc also talks about “middleware” (buff…) which annoy me even
more.
Anyhow I think that what I want to achieve doesn’t require more
middleware.
But I would like to have some “get started” guidelines to work with
RACK. For
example, a ismple example:

A web server that receive a request and replies “200 OK” if the request
URL is
“/yes” and “404 Not Found” is the request URL is “/no”.

Could I get some tips on how to build this simple example with Ebb and
RACK?

Thanks a lot.