When you drop JAR files into the JBOSS_DIST/server/default/deploy/ directory, it will be automatically picked up and processed by the server. All the EJB3 beans defined in the JAR file will then be available to other applications deployed inside or outside of the server via JNDI names like MyBean/local, where MyBean is the implementation class name for the session bean. The deployment is done via the JBoss EJB3 deployer in JBOSS_DIST/server/default/ejb3.deployer/. The META-INF/persistence.properties file we discussed earlier to configure the default behavior of EJB3 entity manager is located in the EJB3 deployer.

The EJB3 deployer automatically scans JARs on the classpath to look for EJB3 annotations. When it finds classes with EJB3 annotations, it would deploy them as EJB3 services. However, scanning all JARs on the classpath could be very time-consuming if you have large applications with many JARs deployed. In the JBOSS_DIST/server/default/ejb3.deployer/META-INF/jboss-service.xml file, you can tell the EJB3 deployer to ignore JARs you know do not contain EJB3 beans. The non-EJB3 JAR files shipped with the JBoss AS are already listed in the jboss.ejb3:service=JarsIgnoredForScanning MBean service:

  ... ...
  <mbean code="org.jboss.ejb3.JarsIgnoredForScanning" 
         name="jboss.ejb3:service=JarsIgnoredForScanning">
      <attribute name="IgnoredJars">
         snmp-adaptor.jar,
         otherimages.jar,
         applet.jar,
         jcommon.jar,
         console-mgr-classes.jar,
         jfreechart.jar,
         juddi-service.jar,
         wsdl4j.jar,
         ... ...
         servlets-webdav.jar
      </attribute>
   </mbean>
  ... ...

		  

You can add any non-EJB3 JARs from your application to this list so that the server do not have to waste time scanning them. This could significantly improve the application startup time in some cases.