JBoss

In short, JBoss is a Open Source J2EE platform implementation.

JBoss has a number of subprojects:

• JBoss AOP, homepage http://www.jboss.org/developers/projects/jboss/aop
• Javassist (Java bytecode manipulation), homepage http://www.jboss.org/developers/projects/javassist.html
• JBossCache (replicated transactional object cache), homepage http://jboss.org/wiki/Wiki.jsp?page=JBossCache
• JGroups (multicast communications), homepage http://www.jgroups.org/
• Hibernate (persistence)
• JBoss-IDE (Eclipse integration), homepage http://www.jboss.org/developers/projects/jboss/jbosside
• Mailservices (under development), homepage http://jboss.org/developers/projects/mailservices/index.html
• Nukes (CMS based on PostNuke), homepage http://www.jboss.org/developers/projects/nukes/index

Taking a look at the implementation, JBoss is one big collection of MBeans:

• JMImplementation
• jboss
• admin
• cache
• deployment
• ejb
• j2ee
• jca
• jdbc
• jmx
• management.local
• mq
• destination
• rmi
• scripts
• security
• system
• web
• jmx.loading

Another document provides details on JBoss internals.