JRuby is not one, but two great technologies: the Ruby language, and the Java Virtual Machine and libraries. In this talk you will learn the basics of programming JRuby, and how to integrate JRuby code into existing Java projects.

JRuby provides a very powerful development platform: the expressiveness and beauty of the Ruby language, with full access to the huge and powerful world of Java libraries. In this talk you will learn to use JRuby as your glue to assemble applications from Java components.

We'll start with how to call Java from Ruby. You will see how to use the high-level API, which provides proxies for Java objects. You will also see how to use the low-level API, where you can get total control via Java reflection.

Next, we'll look at some things you might want to do with JRuby: testing Java code with Test::Unit, automating development processes with Rake, and wrapping useful Java APIs. Oh, and of course, we'll build a Ruby on Rails on Java application.

Finally, we will look at the architecture of JRuby. This is useful so that you can understand what capabilities (and limitations) JRuby has today, and how these are likely to change in the future.