Hello, I have the following problem: I have created a XMBean for JBoss. These MBean and other classes (come I later to speak still on it) I have packed into a sar file. I have built the sar file according to conventions and then have packed it into an ear file. The ear and sar were deployed on the JBoss server. The MBean service is offered properly in the JMX-console. Now I would like to launch the application (my Bean method startJCoServer ()) from the JMX-Console in order to start an application which should listen on a certain port. The start process works as long as as I refer classes which are packed in the sar file. But as soon as classes from jars are needed which are packed in the ear and outside the sar- file, I get a "java.lang. NoClassDefFoundError". My purposes: 1) The above service should launch a so-called "JCo server" (SAP Provider). This appplication accepts inquiries from SAP modules that arrivess at a special port. 2) I would like to launch this server already by the start of the JBoss server by the MBean and I want to stop and start the JCo Server from the JMX-console at any time. My questions: A) What do I make wrong? B) Does not go thus at all? C) Additional question, provided that the above problem is solvable: Can one access a Session Bean that is packed in the ear and want be used by the JCo Server application created from classes inside the sar file? My attempt: I have extended in the SAR the MANIFEST file around suitable Classspath entries (entry jars from ear), but this has also not helped. I am using JBoss 4.3 Greetings from Cologne Peter Boxberg View the original post : http://www.jboss.org/index.html?module=bb&op=viewtopic&p=4239721#... Reply to the post : http://www.jboss.org/index.html?module=bb&op=posting&mode=reply&a...