JBoss has a long history of being one of the most modular application servers in the market. This remains true for WildFly 8. The different Java EE components in WildFly, for example Enterprise JavaBeans (EJB), Java Message Service (JMS), Java Persistence Architecture (JPA), and the WebContainer, are all packaged into something called subsystems or extensions.

All the active extensions in a configuration can easily be located in the activated server configuration file (that is, in standalone*.xml or domain.xml) under the extensions tag.

If the application being deployed does not need all the functionality provided by WildFly, subsystems can easily be removed from the configuration file, thus disabling modules with functionality.

This saves memory, threads, and sometimes startup time; it also improves overall performance. In addition to this, there are also quite a few extensions that utilize lazy loading. This means that they will not be loaded until requested and...