There are many competing and complementary approaches to distributed computing in Java.
The solutions pushed by Sun Microsystems, I.B.M, and many other vendors is Java Enterprise Edition http://java.sun.com/j2ee/index.jsp, including EnterpriseJavaBeans
Although Java Enterprise Edition has found considerable success in the market for serving up web pages, it has found little favour with those trying to accomplish more complex tasks.
An attempt to remedy the shortcomings of Java Enterprise Edition is Java Data Objects http://java.sun.com/products/jdo/index.jsp. This technology suffered at the hands of political shinanigans by the big vendors.
The punters choice is the Hibernate Framework (http://www.hibernate.org).
Other interesting approaches include the KanabosFramework (http://kanabos.dev.java.net), and the Cajo Framework (http://cajo.dev.java.net)
The truly easiest way to do distributing computing in Java is to not do it at all. You'd be surprised how many times this works. -- AndrewMccormick