JRuby-Rack is a lightweight adapter for the Java servlet environment that allows any Rack-based application to run unmodified in a Java servlet container. JRuby-Rack supports Rails, Merb, and any Rack-compatible Ruby web framework.
For more information on Rack, visit http://rack.rubyforge.org/.
For the latest information on JRuby-Rack, please visit JRuby-Rack on Github.