Mizuno is a set of Jetty-powered running shoes for JRuby/Rack.
To use Mizuno with your Rack app:
gem install mizuno
cd /path/to/my/rack/app
mizuno
...and you're off and running. You don't need to set up a Java web container for your Rack application to run under JRuby, because Mizuno works just like Mongrel, WEBRick, Thin, or any other standard Rack handler.
Mizuno also supports asynchronous request handling, via the Java Servlet 3.0 asynchronous processing mechanism
All the speed comes from Jetty 8; Mizuno just ties it to Rack through JRuby's Ruby/Java integration layer.
Note that Mizuno is NOT a direct replacement for jruby-rack or Warbler, because it doesn't produce WAR files or make any attempt to package a Rack application for installation in a Java web container.
You can also run Mizuno via rackup:
rackup -s mizuno
Or with live reloading support:
mizuno --reloadable
Mizuno is licensed under the Apache Public License, version 2.0; see the LICENSE file for details, and was developed on behalf of Mad Wombat Software
Jetty is dual-licensed under the Eclipse and Apache open-source licenses, and its development is hosted by the Eclipse Foundation