O'Reilly Using JRuby 300pages software manual

Now you can bring the best of Ruby into the world of Java, with Using JRuby. Come to the source for the JRuby core team's insights and insider tips. You'll learn how to call Java objects seamlessly from Ruby, and deal with Java idioms such as interfaces and overloaded functions. Run Ruby code from Java, and make a Java program scriptable in Ruby. See how to compile Ruby into .class files that are callable from Java, Scala, Clojure, or any other JVM language.

In Using JRuby you'll venture into the wide world of open-source Ruby and Java libraries. Write Ruby on Rails web applications that run on Java servers like Tomcat. Use Java's JDBC or Hibernate to easily connect Ruby to industry-standard databases. Test your Java program using Ruby's elegant Cucumber and RSpec frameworks. Create dazzling desktop user interfaces with frameworks like Limelight and Monkeybars. Package a Rails or plain Ruby project for easy deployment to any Java environment.

JRuby lets you merge the best of several possible worlds, so you can create unique software using the best tools available. This book is your definitive guide.