Manik requested that I look into making AOP 2.0 independent of concurrent.jar. I've replaces all references to EDU.oswego classes with their java.util.concurrent counteparts. All works fine, apart from org.jboss.aop.proxy.ProxyFactory.createInterfaceProxy, which instantiates a org.jboss.aop.proxy.Proxy which has a field of type GUID(), which uses a SynchronizedLong behind the scenes: | ava.lang.NoClassDefFoundError: EDU/oswego/cs/dl/util/concurrent/SynchronizedLong | at org.jboss.util.id.UID.<clinit>(UID.java:56) | at org.jboss.util.id.VMID.create(VMID.java:258) | at org.jboss.util.id.VMID.getInstance(VMID.java:222) | at org.jboss.util.id.GUID.<init>(GUID.java:64) | at org.jboss.aop.proxy.ProxyFactory.createInterfaceProxy(ProxyFactory.java:62) | at org.jboss.test.aop.proxy.ProxyTestCase.testProxy(ProxyTestCase.java:101) | Is making the jboss.util stuff use a java.util.concurrent.atomic.AtomicLong instead an option? The only other alternative I can see would be to use something other than a GUID in this place. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4040319#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...