The "java:" portion is used by clients that run in the JVM as the things they are looking up (such a local EJBs, even when using the remote interface to access them).
The "comp/env" portion means that the name is registered in a namespace that is local to the web application. In JBoss AS, you need to declare such name mapping in WEB-INF/web.xml and WEB-INF/jboss-web.xml.
The "ejb/ObjectName" is the JNDI name assigned to this item.
Use JNDIView to examine the JNDI tree, that should help you out. http://www.jboss.org/community/wiki/DisplayTheJNDITreeWithTheJMXConsole