JBoss is an open-source and free Java 2 Enterprise Edition (J2EE) application server from the JBoss Group, implemented purely in Java. The JBoss Group, headed by Marc Fleury, is composed of more than 100 developers all over the world. The current major version of JBoss, 3.2, supports most of the J2EE 1.3 features.

1.1 JBoss Components

The JBoss server uses an extremely modular architecture built around Java Management Extensions (JMX). Out of the box, JBoss provides a JMX implementation, an Enterprise JavaBean (EJB) container, and the basic JBoss server. JBoss also comes with a variety of pluggable components that implement the various J2EE standards such as Java Message Service (JMS), Java Naming and Directory Interface (JNDI), Java Authentication and Authorization Service (JAAS), Java Transaction API (JTA)/Java Transaction Service (JTS), and so on.

JBoss allows you to write your own components and plug them into the core JMX implementation, as long as the components you write comply with the JMX specification. This means, for example, if you're not happy with the transaction manager that comes with JBoss, you can write your own transaction manager component and plug it into the JMX bus. You can also add compliant third-party components to JBoss. You'll look at the JBoss JMX implementation in more detail in section 4.2, "JMX in JBoss."