GateKeeper 4.0 needs JSDK which supports Servsupports 1.x. Users can just download JSDK2.1 from JavaSoft web site and put the servlet.jar in the CLASSPATH of GateKeeper. I got the following exception, when I use JSDK2.1 and JDK1.1.8. java.lang.IncompatibleClassChangeError: Unimplemented interface method at com.inprise.vbroker.HIOP.Listener.(Listener.java:81) at com.inprise.vbroker.HIOP.Init$2.create(Init.java:24) at com.inprise.vbroker.ProtocolEngine.GenericSCM.(GenericSCM.java:60) at com.inprise.vbroker.orb.SocketSCM.(SocketSCM.java:132) at com.inprise.vbroker.orb.ORB$4.create(ORB.java:675) at com.inprise.vbroker.ProtocolEngine.ServerEngineImpl.(Compiled Code) at com.inprise.vbroker.ProtocolEngine.ManagerImpl.getServerEngine(ManagerImpl.java:110) at com.inprise.vbroker.poa.POAImpl.(Compiled Code) at com.inprise.vbroker.poa.AdapterManager.vbRootPOA(AdapterManager.java:87) at com.inprise.vbroker.poa.AdapterManager$2.resolve(AdapterManager.java:244) at com.i