JRuby users don't need yet another tutorial on building Rails applications or another treatise on why Entity Beans are Bad Things. They need quick instructions on how to put JRuby to use: how to take advantage of Java's many libraries, how to run Rails web applications inside a Java container, how to integrate with other Java applications, and more. These problems require a cookbook approach, not a tutorial. That's what the "JRuby Cookbook" gives you: a short, concise book that shows, step-by-step, how to solve the problems you face from day to day.