The JBoss EJB container architecture employs a modular plug-in approach. All key aspects of the EJB container may be replaced by custom versions of a plug-in and/or an interceptor by a developer. This approach allows for fine tuned customization of the EJB container behavior to optimally suite your needs. Most of the EJB container behavior is configurable through the EJB JAR META-INF/jboss.xml descriptor and the default server-wide equivalent standardjboss.xml descriptor. We will look at various configuration capabilities throughout this chapter as we explore the container architecture.