RMI Server Basic Problem

Hi,
I have a special problem for which I have no idea at the moment how to solve, although I am pretty new to RMI.
I get this error message
java.rmi.ServerException: RemoteException occurred in server thread; nested exception is:
java.rmi.UnmarshalException: error unmarshalling arguments; nested exception is:
java.lang.ClassNotFoundException: rmikochbuch.RemoteDateImpl_Stub
when I try to start an executable jar-file.
What I have is:
On my development PC (Win2k WS) I run
java -jar RMI_Server_Test_01.jar
(of course after "start rmiregistry") and it works. Now I take this jar file and copy it to two other PCs (Win XP / Win2k Server). So when I try to start my jar file on these machines too, I get the error messages you see above. All three machines have the same SDK 1.4.2_07 installed.
I have neither an explanation why it does not work on the other machines nor do I have any idea how to solve this problem. :(
Additional info:
The error message occurs in this code block:
      RemoteDateImpl im = new RemoteDateImpl();
      System.out.println( "DateServer starting..." );
      Naming.rebind( RemoteDate.LOOKUPNAME, im );The "DateServer starting..." gets displayed but then the program crashes and exits.

Got this problem solved now.
What I had to do - and this is not mentioned in the Java cookbook (O'Reilly):
Copy the Interface, the Implementation plus Stub + Skel .class files to the CLASSPATH on the server.
Now comes the second part - connect from a client to this server...

Similar Messages

RMI Server Offline Problem

Hello all, I am e newbie in the world of RMI programming. I have developed an application that can control two devices over the internet. The code files are given below :
Parallel.java
import java.rmi.*;
public interface Parallel extends Remote
     void relayDriver(byte k) throws RemoteException;
     byte currentStatus() throws RemoteException;
ParallelImpl.java
import parport.ParallelPort;
import java.rmi.*;
import java.rmi.server.*;
public class ParallelImpl extends UnicastRemoteObject implements Parallel
     private Byte ctrlValue;
     ParallelPort lpt1 = new ParallelPort(0x378); // 0x378 is normally the base address for the LPT1 port
     public ParallelImpl(byte a) throws RemoteException
          ctrlValue = a;
          lpt1.write(ctrlValue);
          System.out.println("Device Actuation Code "+ctrlValue);
     public void relayDriver(byte k) throws RemoteException
          ctrlValue = k;
          System.out.println("Device Actuation Code "+ctrlValue);
          lpt1.write(ctrlValue);
     public byte currentStatus() throws RemoteException
return ctrlValue;
ParallelClient.Java
import java.io.*;
import java.rmi.*;
import java.rmi.server.*;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class ParallelClient extends JApplet implements ActionListener
     Byte g;
     String url = "rmi://169.254.196.149/";
     private Container container;
     private javax.swing.JTextArea resultArea;
     public void init()
          container = getContentPane();
          container.setLayout( new BorderLayout() );
          resultArea = new javax.swing.JTextArea();
          JRadioButton buttonZero = new JRadioButton("No Device
On");
     buttonZero.setMnemonic(KeyEvent.VK_A);
     buttonZero.setActionCommand("0");
     buttonZero.setSelected(true);
     JRadioButton buttonOne = new JRadioButton("Device 1 On
Only");
     buttonOne.setMnemonic(KeyEvent.VK_B);
     buttonOne.setActionCommand("1");
     JRadioButton buttonTwo = new JRadioButton("Device 2 On
Only");
     buttonTwo.setMnemonic(KeyEvent.VK_C);
     buttonTwo.setActionCommand("2");
     JRadioButton buttonThree = new JRadioButton("Device 1
and 2 Both On");
     buttonThree.setMnemonic(KeyEvent.VK_D);
     buttonThree.setActionCommand("3");
     //Group the radio buttons.
     ButtonGroup group = new ButtonGroup();
     group.add(buttonZero);
     group.add(buttonOne);
     group.add(buttonTwo);
     group.add(buttonThree);
     //Register a listener for the radio buttons.
     buttonZero.addActionListener(this);
     buttonOne.addActionListener(this);
     buttonTwo.addActionListener(this);
     buttonThree.addActionListener(this);
          JPanel radioPanel = new JPanel(new GridLayout(0, 1));
     radioPanel.add(buttonZero);
     radioPanel.add(buttonOne);
     radioPanel.add(buttonTwo);
     radioPanel.add(buttonThree);
     container.add(radioPanel, BorderLayout.LINE_START);
          container.add(resultArea, BorderLayout.SOUTH);
     public void actionPerformed(ActionEvent e)
          try
               Parallel r1 = (Parallel)Naming.lookup(url +
"inival");
               if(r1.currentStatus()==0)
                         resultArea.setText("Previous
Status: No Devices Online....");
                    else if(r1.currentStatus()==1)
                         resultArea.setText("Previous
Status: Device 1 Online. Device 2 Offline.");
                    else if(r1.currentStatus()==2)
                         resultArea.setText("Previous
Status: Device 2 Online. Device 1 Offline.");
                    else
                         resultArea.setText("Previous
Status: Device 1 & 2 both are Online.");
               g = Byte.parseByte(e.getActionCommand());
               r1.relayDriver(g);
               if(r1.currentStatus()==0)
                         resultArea.setText("Current
Status: No Devices Online....");
                    else if(r1.currentStatus()==1)
                         resultArea.setText("Current
Status: Device 1 Online. Device 2 Offline.");
                    else if(r1.currentStatus()==2)
                         resultArea.setText("Current
Status: Device 2 Online. Device 1 Offline.");
                    else
                         resultArea.setText("Current
Status: Device 1 & 2 both are Online.");
          catch(Exception et)
               resultArea.setText("Server OffLine");
ParallelServer.java
import java.io.*;
import java.rmi.*;
import java.rmi.server.*;
public class ParallelServer
     public static void main(String args[])
          try
               System.out.println("Constructing Server Implementations ....");
               ParallelImpl p1 = new ParallelImpl((byte)0);
               System.out.println("Binding Server Implementation to registry ....");
               Naming.rebind("inival",p1);
               System.out.println("Waiting for invocations from Client ....");
          catch(Exception e)
               System.out.println("Server is Offline or Line has broken. Error : "+ e);
The corresponding stub files, class files have been loaded on the internet. http://rcviproject.110mb.com/
On the server machine the rmi registry is on and the ParallelServer program is also running. But when the applet at the URL is actuated then it shows 'server offline'. Why is this happening? Please help.

That did not print anything. The server when started by the following commands :
start rmiregistry
start java ParallelServer
continues to run at Waiting for invocation from client ...... no error msg is shown.
do i need tomcat on the server machine in addition to this ?

RMI Server and RMI Client Problem

First, Hi!
I have create my RMI Server and a RMI Servlet client.
I can run the server and servlet first time and it works fine.
Then, I stop rmiregistry and server.
Then, I start rmiregistry and server for a second time but my RMI Servlet client gets a
java.rmi.ConnectException: Connection refused to host: xxx.xxx.xxx.xxx; nested exception is: java.net.ConnectException: Connection refused
If I copy the class again where the servlets resides, it works again. But I have to keep doing that. I have to keep copying the class file to the servlet directory every 2nd time I try to run it for it to work.
Anyone know what am I doing wrong?

First, Hi!
I have create my RMI Server and a RMI Servlet client.
I can run the server and servlet first time and it
works fine.
Then, I stop rmiregistry and server.
Then, I start rmiregistry and server for a second time
but my RMI Servlet client gets a
java.rmi.ConnectException: Connection refused to host:
xxx.xxx.xxx.xxx; nested exception is:
java.net.ConnectException: Connection refused
If I copy the class again where the servlets resides,which class file ? u mean RMIServer's class files ??
I have faced the same problem too. In my case if i just restart my Tomcat webserver the error goes and the servlet is very well able to connect back to the RMI Server
it works again. But I have to keep doing that. I have
to keep copying the class file to the servlet
directory every 2nd time I try to run it for it to
work.
Anyone know what am I doing wrong?

My first RMI server: problem

Hi,
I'm just trying to create my first RMI program, but I got already blocked immediately:
It's just a stupid program with a function that returns "ok".
So what I did is the following:
1)I created a class OkServer.java
import java.rmi.Remote;
import java.rmi.RemoteException;
public interface OkServer extends Remote {
public String getOk() throws RemoteException;
2)I created a class OkServerImpl.java
import java.rmi.server.UnicastRemoteObject;
import java.rmi.RMISecurityManager;
import java.rmi.RemoteException;
import java.rmi.Naming;
public class OkServerImpl extends UnicastRemoteObject implements OkServer {
public OkServerImpl() throws RemoteException {
public String getOk() {
     return "ok";
public static void main (String args[]) throws Exception {
          System.setSecurityManager(new RMISecurityManager());
          OkServerImpl OkSvr = new OkServerImpl();
          Naming.bind("OkServer", OkSvr);
3) I compiled everything with javac *.java
i use java version below:
java version "1.5.0_12"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.5.0_12-b04)
Java HotSpot(TM) Client VM (build 1.5.0_12-b04, mixed mode)
4)I opened a cmd window and started the registry with the command c:\rmiregistr
(a cursor starts blinking, so I think it runs correctly)
5)then I start the program with the command: C:\java OkServerImpl
but I get the error below !!
C:\Temp\rmitester>java OkServerImpl
Exception in thread "main" java.security.AccessControlException: access denied (java.net.SocketPermission 127.0.0.1:1099 connect,resolve)
at java.security.AccessControlContext.checkPermission(AccessControlContext.java:264)
at java.security.AccessController.checkPermission(AccessController.java:427)
at java.lang.SecurityManager.checkPermission(SecurityManager.java:532)
at java.lang.SecurityManager.checkConnect(SecurityManager.java:1034)
at java.net.Socket.connect(Socket.java:513)
at java.net.Socket.connect(Socket.java:469)
at java.net.Socket.<init>(Socket.java:366)
at java.net.Socket.<init>(Socket.java:179)
at sun.rmi.transport.proxy.RMIDirectSocketFactory.createSocket(RMIDirectSocketFactory.java:22)
at sun.rmi.transport.proxy.RMIMasterSocketFactory.createSocket(RMIMasterSocketFactory.java:128)
at sun.rmi.transport.tcp.TCPEndpoint.newSocket(TCPEndpoint.java:569)
at sun.rmi.transport.tcp.TCPChannel.createConnection(TCPChannel.java:185)
at sun.rmi.transport.tcp.TCPChannel.newConnection(TCPChannel.java:171)
at sun.rmi.server.UnicastRef.newCall(UnicastRef.java:306)
at sun.rmi.registry.RegistryImpl_Stub.bind(Unknown Source)
at java.rmi.Naming.bind(Naming.java:111)
at OkServerImpl.main(OkServerImpl.java:18)
What's wrong???

solved, but i don't understand why i encountered this particular issue (that isn't mentioned to happen or to configure in my book):
i had to create a custom policy file:
make a file "c:\temp\rmitester\policy.all" and past the text below in it:
grant {
permission java.security.AllPermission "", "";
thereafter launch the server with this command:
c:\temp\rmitester\java -Djava.security.policy=policy.all OkServerImpl
and the client with this command:
c:\temp\rmitester\java -Djava.security.policy=policy.all OkClient localhost
Can anyone explain if it was normal that i encountered this problem or was it seldom behaviour that happens only to me?

Registry on RMI Server problem

I have a rmi server app. running 24/7 on a Win2K box with clients connecting locally and over the Internet. Every so often the clients cannot connect and/or currently connected clients cannot communicate with the server. Sometimes we go a month without this happening and sometimes it happens twice in a day. When it does happen, the server app. is still fully functionally. It appears that the registry is locked or corrupt. Clients attempting to connect suceed with the Naming.lookup, but fail after that. When this happens I stop and restart the server app. and the clients can then automatically reconnect. I see other people have had this problem but I haven't seen any solution.
Thanks.

Seems as if a bug.
For more details refer to
http://developer.java.sun.com/developer/technicalArticles/RMI/rmi/

Problem with lost of the access to the RMI server

Hi to all.
We have two applications. First one (master) provides to second (slave) through RMI service their data or other resources.
In the ordinary way all works fine. But if we need for some reason restart master application, slave can't access to the RMI service and calling of the method Naming.lookup(...) throws java.rmi.UnmarshalException: error unmarshalling return; nested exception is: java.io.EOFException
Interestingly, calling of method Namig.list(...) at this moment correctly returns an array of the names bound in the registry.
For completeness, in the time of restarting master application, classes of the RMI services are not changed and thus Stub/Skeleton classes are same on both sides.
What is reason for this behaviour? It is way to restart/restore RMI access of the slave application to the master without restarting server (Tomcat) of both applications?
Thank, Roman

Thank for your reply, but your suggestion not helped me now.
For registering and binding I used usual practices. Following snippets of code are inside method that perform initialization on application startup. I was trying three versions.
First version creates registry and binds service classes only. Without any checks.
try {
LocateRegistry.createRegistry(rmiPort);
String ip = Functions.getCurrentEnvironmentNetworkIp();
if (ip.startsWith("?"))
    throw new Exception("Can't retrieve application IP address.");
logger.info("Application IP address: " + ip);+
RMIServiceCommonImpl rmiServiceCommon = new RMIServiceCommonImpl();
String name = "rmi://" + ip + ":" + rmiPort + "/";
Naming.rebind(name + IRMIServiceCommon.RMI_SERVICE_COMMON_NAME, rmiServiceCommon);
catch (Exception e) {
logger.error("Failed to register RMI services: ", e);
}On first application start all is OK and client has no problem to access RMI service.
But if master application is restarted, calling of the method LocateRegistry.createRegistry(rmiPort); throws
java.rmi.server.ExportException: internal error: ObjID already in use
Since that, client can't access to the RMI service and following code (method Naming.lookup) throws
java.rmi.UnmarshalException: error unmarshalling return; nested exception is: java.io.EOFException
String name = "rmi://" + ConfigServlet.getProperty("rmiHostUrl") + "/";
IRMIServiceCommon service = (IRMIServiceCommon) Naming.lookup(name + IRMIServiceCommon.RMI_SERVICE_COMMON_NAME);Second version checks if registry exist and trying to get list of registered services. If services not exist Register is created.
try {
Registry reg = LocateRegistry.getRegistry(rmiPort);
String[] list = null;
try {
    list = reg.list();
catch (Exception ex) {
    // ignore
if (list == null || list.length == 0)
    LocateRegistry.createRegistry(rmiPort);
String ip = Functions.getCurrentEnvironmentNetworkIp();
if (ip.startsWith("?"))
    throw new Exception("Can't retrieve application IP address.");
logger.info("Application IP address: " + ip);
String name = "rmi://" + ip + ":" + rmiPort + "/";
RMIServiceCommonImpl rmiServiceCommon = new RMIServiceCommonImpl();
Naming.rebind(name + IRMIServiceCommon.RMI_SERVICE_COMMON_NAME, rmiServiceCommon);
catch (Exception e) {
logger.error("Failed to registering RMI services: ", e);
}Again, first start is OK.
In this case, after application restart, calling of method Naming.rebind() throws
java.lang.IllegalStateException at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1272)
INFO: Illegal access: this web application instance has been stopped already. Could not load eu.arachne.rmi.RMIServiceCommonImpl_Stub.
This exception is followed by similar exceptions, but differs in class names (stubs) - java.rmi.server.RemoteStub, java.rmi.server.RemoteObject, java.rmi.dgc.Lease, java.rmi.dgc.VMID, java.rmi.server.UID
Of course, client application can't access to the service.
The third version first unbinds all services and then performs binding again.
if (list == null || list.length == 0)
LocateRegistry.createRegistry(rmiPort);
else {
for (int ii = 0; ii < list.length; ii++)
    Naming.unbind(name + list[ii]);
}But again, rebinding fail as I mentioning above.
I don't know... :-( How I can solve this problem?
Thank, Roman

Rmi server problem

hi
Can anybody tell me how to stop the Jvm to free the Rmi server port and the remote object?

Hi,
The first step: unbind the bound object from the registry!
As far as I know the UnicastRemoteObject calls the exportObject() method in its constructor. If you want to force the unregistering call the UnicastRemoteObject's unexportObject() method on the server object.
After these two calls (Naming.unbind(), UnicastRemoteObject.unexportObject()) the server object surely is no longer listening the remote calls, the JVM exits smothly...
Sany

Problem in starting RMI server, please help!

Hi , all:
I am learning RMI from SUN's tutorial. I set all of program packages as same as the tutorial, compiled all of programs . and built all of the jar files, the server classes and the client classes.When I run the server, ComputeEngine, it did not work ,and the following messages were showed at command lines:
C:\RMI\doc>java -Djava.rmi.server.codebase=file:/c:\rmi\ann\public_html\classes/
-Djava.rmi.server.hostname=localhost -Djava.security.policy=java.policy eng
ine.ComputeEngine
ComputeEngine exception: access denied (java.net.SocketPermission 127.0.0.1:1099
connect,resolve)
java.security.AccessControlException: access denied (java.net.SocketPermission 1
27.0.0.1:1099 connect,resolve)
at java.security.AccessControlContext.checkPermission(AccessControlConte
xt.java:272)
at java.security.AccessController.checkPermission(AccessController.java:
399)
at java.lang.SecurityManager.checkPermission(SecurityManager.java:545)
at java.lang.SecurityManager.checkConnect(SecurityManager.java:1044)
at java.net.Socket.<init>(Socket.java:262)
at java.net.Socket.<init>(Socket.java:100)
at sun.rmi.transport.proxy.RMIDirectSocketFactory.createSocket(RMIDirect
SocketFactory.java:25)
at sun.rmi.transport.proxy.RMIMasterSocketFactory.createSocket(RMIMaster
SocketFactory.java:120)
at sun.rmi.transport.tcp.TCPEndpoint.newSocket(TCPEndpoint.java:499)
at sun.rmi.transport.tcp.TCPChannel.createConnection(TCPChannel.java:190
at sun.rmi.transport.tcp.TCPChannel.newConnection(TCPChannel.java:174)
at sun.rmi.server.UnicastRef.newCall(UnicastRef.java:318)
at sun.rmi.registry.RegistryImpl_Stub.rebind(Unknown Source)
at java.rmi.Naming.rebind(Naming.java:160)
at engine.ComputeEngine.main(ComputeEngine.java:25)
Please give helps .
Thanks!

Thank.
Thank.
I have put them at the same directory, but is deos not work.
Something I am not sure.
On the SUN's tutorial , the follows is given:
Win32:
java -Djava.rmi.server.codebase=file:/c:\home\ann\public_html\classes/
-Djava.rmi.server.hostname=zaphod.east.sun.com
-Djava.security.policy=java.policy
engine.ComputeEngine
I changed hostname = localhost
I also changed the code of the server class given by tutorial :
String name = "//host/Compute" ;
to:
String name = "//localhost/Compute";
Should I make such changes?
Here is the server class given by the tutorial:
package engine;
import java.rmi.*;
import java.rmi.server.*;
import compute.*;
public class ComputeEngine extends UnicastRemoteObject
implements Compute
public ComputeEngine() throws RemoteException {
super();
public Object executeTask(Task t) {
return t.execute();
public static void main(String[] args) {
if (System.getSecurityManager() == null) {
System.setSecurityManager(new RMISecurityManager());
String name = "//host/Compute";
try {
Compute engine = new ComputeEngine();
Naming.rebind(name, engine);
System.out.println("ComputeEngine bound");
} catch (Exception e) {
System.err.println("ComputeEngine exception: " +
e.getMessage());
e.printStackTrace();

Problem in starting RMI server, help please

Hi , all:
I am learning RMI from SUN's tutorial. I set all of program packages as same as the tutorial, compiled all of programs . and built all of the jar files, the server classes and the client classes.When I run the server, ComputeEngine, it did not work ,and the following messages are showed at command lines:
C:\RMI\doc>java -Djava.rmi.server.codebase=file:/c:\rmi\ann\public_html\classes/
-Djava.rmi.server.hostname=localhost -Djava.security.policy=java.policy eng
ine.ComputeEngine
ComputeEngine exception: access denied (java.net.SocketPermission 127.0.0.1:1099
connect,resolve)
java.security.AccessControlException: access denied (java.net.SocketPermission 1
27.0.0.1:1099 connect,resolve)
at java.security.AccessControlContext.checkPermission(AccessControlConte
xt.java:272)
at java.security.AccessController.checkPermission(AccessController.java:
399)
at java.lang.SecurityManager.checkPermission(SecurityManager.java:545)
at java.lang.SecurityManager.checkConnect(SecurityManager.java:1044)
at java.net.Socket.<init>(Socket.java:262)
at java.net.Socket.<init>(Socket.java:100)
at sun.rmi.transport.proxy.RMIDirectSocketFactory.createSocket(RMIDirect
SocketFactory.java:25)
at sun.rmi.transport.proxy.RMIMasterSocketFactory.createSocket(RMIMaster
SocketFactory.java:120)
at sun.rmi.transport.tcp.TCPEndpoint.newSocket(TCPEndpoint.java:499)
at sun.rmi.transport.tcp.TCPChannel.createConnection(TCPChannel.java:190
at sun.rmi.transport.tcp.TCPChannel.newConnection(TCPChannel.java:174)
at sun.rmi.server.UnicastRef.newCall(UnicastRef.java:318)
at sun.rmi.registry.RegistryImpl_Stub.rebind(Unknown Source)
at java.rmi.Naming.rebind(Naming.java:160)
at engine.ComputeEngine.main(ComputeEngine.java:25)
Please give helps .
Thanks!

You are setting the security policy to the file named
java.policy, make sure that it is in the same
directory where you are invoking the java compiler.Thank.
I have put them at the same directory, but is deos not work.
Something I am not sure.
On the SUN's tutorial , the follows is given:
Win32:
java -Djava.rmi.server.codebase=file:/c:\home\ann\public_html\classes/
-Djava.rmi.server.hostname=zaphod.east.sun.com
-Djava.security.policy=java.policy
engine.ComputeEngine
I changed hostname = localhost
I also changed the code of the server class given by tutorial :
String name = "//host/Compute" ;
to:
String name = "//localhost/Compute";
Should I make such changes?
Here is the server class given by the tutorial:
package engine;
import java.rmi.*;
import java.rmi.server.*;
import compute.*;
public class ComputeEngine extends UnicastRemoteObject
implements Compute
public ComputeEngine() throws RemoteException {
super();
public Object executeTask(Task t) {
return t.execute();
public static void main(String[] args) {
if (System.getSecurityManager() == null) {
System.setSecurityManager(new RMISecurityManager());
String name = "//host/Compute";
try {
Compute engine = new ComputeEngine();
Naming.rebind(name, engine);
System.out.println("ComputeEngine bound");
} catch (Exception e) {
System.err.println("ComputeEngine exception: " +
e.getMessage());
e.printStackTrace();

Problem connecting RMI-Server using a servlet

Hi All..
I have a RMI-client server model woring fine in AIX box.I am currently in a need to create one web client(may be with servlet or JSP).
I wrote a sample servlet which try to connect to the RMI server. But when I run the servlet Its simply try to connect and then wait for unlimited time,not even print any exception/error.
Both my RMI sevrer and Tomcat are in the same box.
I am sending the servlet code for your reference.
import java.rmi.*;
import java.rmi.registry.Registry;
import java.rmi.registry.LocateRegistry;
import javax.servlet.*;
import javax.servlet.http.*;
import java.io.*;
import ir77.mon.engine.*;
public class WebClient extends HttpServlet
public void doGet(HttpServletRequest req, HttpServletResponse res) throws ServletException, IOException
XmlServerIntf xmlServerIntf = null;
PrintWriter out = res.getWriter();
res.setContentType("text/plain");
try{
out.println("Connecting to server......");
//Seems this one is sufficient.(either this code or the below one)
//String strServerUrl = "rmi://" + "192.168.100.22" + "/ir77.mon.engine";
//xmlServerIntf = (XmlServerIntf) Naming.lookup(strServerUrl);
//Try with this one also
Registry reg = LocateRegistry.getRegistry("192.168.100.22", 2004);
xmlServerIntf = (XmlServerIntf) reg.lookup("rmi://192.168.100.22/ir77.mon.engine");
out.println("Connected to server");
catch (Exception e){
System.out.println("Exception in WebClient"+e);
when I run the servlet in the browser with "http://192.168.100.22:8080/WebClient" its simply prints " Connecting to server......" and waits.
Note : 192.168.100.22 - where my rmi server starts and 2004 -where I created by rmiregistry.I created it using LocateRegistry.createRegistry(2004);
I have tried starting tomcat with "-security" option too but no responds as well.
Do I have to provide some grant permission in catlina.policy file?If yes what?
currently I have tried with giving all permission..
Do I need to change the RMI server code?
Any help will be highly appreciated....

Hi genady,
Oh....Ya I like to...I thought no body was interested...as I didn't get any reply from anybody....
Well The first thing is that with the look up method in the servlet
it should be like :
Registry reg = LocateRegistry.getRegistry("ip address of the rmi server", port number);
RMIServerInterface = (type cast with RMIServerInterface) reg.lookup("rmi binding string");
Now you are able to get the server interface object & you can call any method.
Next you have to provide the grant permission in the catalina.policy file to the folder where you have your application like....
grant codeBase "file:${catalina.home}/webapps/ROOT/WEB-INF/classes/-" {
permission java.security.AllPermission;
Or you can give specific permissions also.
Finally you have to run the tomcat as : $catalina.sh start -security
Note: One more thing you have to keep in mind that's the structure of your application. ie com.mon.yourapp.......u have to create the same structure in tomcat's classes folder .
Its done...........

J2EE problem while accessing RMI server

Hi,
I have a J2EE application in Oracle 9iAS server, I have created an application which access a RMI Server runs in a different PC, it works fine in my /dev site, I moved the same files to /test site (Same machine but different context), which also access the same RMI Server, now my application throws the following error in /test site where as it is working perfectly in /dev site.
If you have any idea on this please let me know. Thanks in advance.
Regards,
Venkat
----------- Exception throws in server --------------------
500 Internal Server Error
java.lang.ClassFormatError: com/sgsap/feed/server/IFeed (Extra bytes at the end of the class file) at java.lang.ClassLoader.defineClass0(Native Method) at java.lang.ClassLoader.defineClass(ClassLoader.java:493) at com.evermind[Oracle9iAS (1.0.2.2) Containers for J2EE].naming.ContextClassLoader.findClass(ContextClassLoader.java:250) at java.lang.ClassLoader.loadClass(ClassLoader.java:299) at java.lang.ClassLoader.loadClass(ClassLoader.java:255) at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:315) at java.lang.ClassLoader.defineClass0(Native Method) at java.lang.ClassLoader.defineClass(ClassLoader.java:493) at com.evermind[Oracle9iAS (1.0.2.2) Containers for J2EE].naming.ContextClassLoader.findClass(ContextClassLoader.java:250) at java.lang.ClassLoader.loadClass(ClassLoader.java:299) at java.lang.ClassLoader.loadClass(ClassLoader.java:255) at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:315) at java.lang.Class.forName0(Native Method) at java.lang.Class.forName(Class.java:195) at java.io.ObjectInputStream.resolveClass(ObjectInputStream.java:654) at sun.rmi.server.MarshalInputStream.resolveClass(MarshalInputStream.java:121) at java.io.ObjectInputStream.inputClassDescriptor(ObjectInputStream.java:918) at java.io.ObjectInputStream.readObject(ObjectInputStream.java:366) at java.io.ObjectInputStream.readObject(ObjectInputStream.java:236) at java.io.ObjectInputStream.inputObject(ObjectInputStream.java:1186) at java.io.ObjectInputStream.readObject(ObjectInputStream.java:386) at java.io.ObjectInputStream.readObject(ObjectInputStream.java:236) at sun.rmi.registry.RegistryImpl_Stub.lookup(Unknown Source) at java.rmi.Naming.lookup(Naming.java:84) at com.sgsap.feed.client.FeedClient.getData(FeedClient.java:99) at ReportManager.updatePostTradeFeedServerValues(ReportManager.java:998) at ReportManager.updatePostTradeFeedValues(ReportManager.java:961) at ReportManager.getPostTradeData(ReportManager.java:1449) at /html/Trade/PostTradeReportExcel.jsp._jspService(/html/Trade/PostTradeReportExcel.jsp.java:84) (JSP page line 44) at com.orionserver[Oracle9iAS (1.0.2.2) Containers for J2EE].http.OrionHttpJspPage.service(OrionHttpJspPage.java:54) at com.evermind[Oracle9iAS (1.0.2.2) Containers for J2EE].server.http.HttpApplication.serviceJSP(HttpApplication.java:5458) at com.evermind[Oracle9iAS (1.0.2.2) Containers for J2EE].server.http.JSPServlet.service(JSPServlet.java:31) at com.evermind[Oracle9iAS (1.0.2.2) Containers for J2EE].server.http.ServletRequestDispatcher.invoke(ServletRequestDispatcher.java:501) at com.evermind[Oracle9iAS (1.0.2.2) Containers for J2EE].server.http.ServletRequestDispatcher.forwardInternal(ServletRequestDispatcher.java:170) at com.evermind[Oracle9iAS (1.0.2.2) Containers for J2EE].server.http.HttpRequestHandler.processRequest(HttpRequestHandler.java:576) at com.evermind[Oracle9iAS (1.0.2.2) Containers for J2EE].server.http.HttpRequestHandler.run(HttpRequestHandler.java:189) at com.evermind[Oracle9iAS (1.0.2.2) Containers for J2EE].util.ThreadPoolThread.run(ThreadPoolThread.java:62)

Looks like ClassLoader tries to load different class. Check your classpath, check where are classes com/sgsap/feed/server/IFeed and if there are more than one such class, check why if your app is in /dev it is loading different class than when it is in /test.
Other solution could be that something gone wrong while compilation. Are you sure you was not recompiling any code between testing it on /dev and on /test?
I do not know, I am just trying to give some clues.
Regards
Pawel

RMI server appears to deadlock but is fine after...

I have a RMI server that is providing services to clients on my network.
When I run tests from the clients (an app that constatnly makes demanding method calls to the RMI server) everything runs fine.
I have one Windows 2000 client and one Slackware Linux 10.1 client, everyone has the same version JVM. They both run the "stress test" at the same time. The Server is a Windows XP MCE on a dual core Processor, the OS has been configured to run both processors.
Both clients run for hours (all day) and so does the server without problem. Except sometimes I come back and it looks as though my clients are expererinceing some type of deadlock and when I check the server it is sitting there not doing anything as if everything is deadlocked.
Now the magic, at the server console I smack a few keys on the keyborad and everything jumps back into business humming along just fine.
What the heck? I have had this happen more than once. My apps have no input facilities whatsoever except CTRL+C which I use to kill them when I'm done with my "stress test".
I have noticed Windows clients can kinda drag everyone else down because of the way it schedules threads.
Any ideas?
Sean

Sometimes thread prioroties can be used effectivly on
Windows if you are having problems with your WINDOWS
machines handling the threads "properly". But not
much use really.
For testing? OK.
I have been developing and testing parallel threaded
applcations and it would not be possible without a
dual-processor machine (properly configured).
Number of processors is irrelevant. Why do you think this makes any difference at all?
You cannot test threaded applications on a single
processor. Single processor runs ONE thread at a
time. Dual-Core or dual processors can run THREADS
in parallel. I've seen it work, beautifully. your
threaded app may run fine on one processor BUT if you
run it on a dual machine it may break. In computer
science parallel computing has been around for a long
time but the majority of people (programmers) have no
idea about it whatsoever and there is a lot of
misconceptions.
I happen to have a Masters in distributed computing. I quite enjoy it. And I still insist that a dual core system is not going to do anything to your threads that a single core system won't do to your threads.
I challenge you to write a program that can tell the number of processors present, without checking the system property. If the OS is properly written and the chipset is working as it should, your program can not tell.
One thing I see repeated is that dual-core machines
have liitle impact on performance because most
applications have only a single thread. Horse
feathers!!! Windows and any other OS is going to run
applications in parallel!! I have noticed a nice
improvemnet in basic operations on a dual-core
(properly configured).
applications don't run in parallel, threads do. adding a 2nd core may make your computer more responsive if the OS preemptive scheduler is poorly written. Otherwise its no different than adding a faster CPU.
This is a wonderful subject (Parallel Computing, the
new PC)and I'm hooked (bad) mainly because this area
is almost unexplored by the masses and there is a lot
of work (read innovation) that needs done in the next
decade on the software end. If you like serious PC
check out Solaris (awsome).I love it. I was working on parallel code in Linux several years back while in school. Its not unexplored really. Search for distributed computing and you will find lots of info. The thing that is new is the attempt to take advantage automagically of multi cpu by programs that were not written to take advantage.
>
P.S. My dual-core 1gig SATA (XPS) Dell machine just
caught up with my PIII single CPU 512mb SCSI U-160
(500sc)machine in total throughput. seat-of-pants
All this swapping has to go.
Sean
Message was edited by:
DataVirtueMy last dual cpu machine was a abit BP6 dual celeron. Its a nice novelty, but buying dual/cpu dual core makes no sense unless the fastest single CPU is not fast enough or the price is right. Dual-cores has come about because the CPU folks are having difficulty making the single CPUs faster. Its a cop-out really. Instead of advancing technology, they add a 2nd CPU and try to act like they did something.
Anyone that chooses a dual-core CPU over a twice as fast single core CPU either does not understand distributed computing, or enjoys the novelty.

RMI SERVER behind the router....!!!!!!!!!!!!

Hi I am new here...And Have a problem regarding to java RMI...
I have a uni assignment which asks us to write an online tic tac toe game using RMI..well assigment only request if it can be run on the same machine and I finished..
But now I am trying to config it to real life with internet instead of LAN.
Basically I have one static IP assigned by my ISP... and I have local IP addresses on my machines. The addresses will be translated by my router to the public one...
My server is running on port 8081 of my server computer with an local IP addresses... and I did port forwarding in my router to forward all the 8081 request to this server...
And the the client use the public IP to locate my server they can acctually connect to my server and get the stub or ref to it...But when they acctually trying to call a method on
the server side, I realised they actually using the local IP addresses of my server machine instead of the public one..so i think the stub acctually bind the machine IP and ask client to use this IP to communicate.
This obviously not going to work...And In the API it seems like I can not acctually do anything about IP address when create the Registry..
Any clue on this Thank you.......

No, the stub consists of a single Java object which contains the IP address and port number of the host from which the remote object was exported. The client knows the initial lookup address for the Registry but it performs all subsequent communications via the information embedded in the stub.
@OP: you need to export your remote object on a fixed port, have the router forward that port, and set the system property java.rmi.server.hostname in the server JVM to the external IP address of the router.

RMI Server Codebase Permission Denied

I'm having a problem trying to get my application running in a test environment. I currently have this same application up and running in an almost identical location without any issues, and I'm at a loss to understand what the problem is.
My application is an RMI server-client setup. At the moment, I'm having trouble with solely the server portion, as I'm unable to get it to access the codebase. I start the application with the following runServer.sh file (located in /usr/local/app/app, so the $ROOT_DIR=pwd is correct):
Line: -----
#!/bin/bash
ROOT_DIR=`pwd`
JAVA_HOME=/usr/java/latest
CLASSPATH=''
#:: Please edit the environmental variables below so that it refers
#:: to the location where you have distribution URL.
DISTRIBUTION_URL=file://$ROOT_DIR
find /usr/local/app/app/server -name '*.jar' -type f -print | while read FILE
do
if [ $CLASSPATH ]
then
     CLASSPATH=$CLASSPATH:$FILE
else
     CLASSPATH=$FILE
fi
echo $CLASSPATH > classpath.env
done
read CLASSPATH < classpath.env
find /usr/local/app/app/import -name '*.jar' -type f -print | while read FILE
do
if [ $CLASSPATH ]
then
     CLASSPATH=$CLASSPATH:$FILE
else
     CLASSPATH=$FILE
fi
echo $CLASSPATH > classpath.env
done
read CLASSPATH < classpath.env
find /usr/local/app/app/common -name '*.jar' -type f -print | while read FILE
do
if [ $CLASSPATH ]
then
     CLASSPATH=$CLASSPATH:$FILE
else
     CLASSPATH=$FILE
fi
echo $CLASSPATH > classpath.env
done
read CLASSPATH < classpath.env
echo ${CLASSPATH}
cd server
# start /min "RMI Registry"
$JAVA_HOME/bin/rmiregistry &
JAVA_SECURITY="-Djava.security.policy==config/admin.policy -Djava.security.auth.login.config==config/app_jaas.config"
IMPORT_PROPERTIES="-Dapp.import.properties=file://$ROOT_DIR/import/config/import.properties -Dapp.import.logging.properties=file://$ROOT_DIR/import/config/importlog.properties -Dapp.client.properties=file://$ROOT_DIR/client/config/client.properties"
app_PROPERTIES="-Dapp.root=$ROOT_DIR -Dconnection.pool.properties=file://$ROOT_DIR/server/config/database.properties -Dapp.common.properties=$DISTRIBUTION_URL/common/config/common.properties -Dapp.server.properties=file://$ROOT_DIR/server/config/server.properties -Dapp.server.logging.properties=file://$ROOT_DIR/server/config/log.properties"
echo
echo "-------------- app Server -------------------"
echo
$JAVA_HOME/bin/java -ms96m -mx256m -classpath $CLASSPATH -Djava.rmi.server.codebase=file:///usr/local/app/app/common/lib/common.jar $IMPORT_PROPERTIES $JAVA_SECURITY $app_PROPERTIES -Xdebug -Xnoagent -Xrunjdwp:transport=dt_socket,server=y,address=8000,suspend=n app.serverimpl.ServerStarter
cd $ROOT_DIR
Line: -----
After running this, it fails at that last line, $JAVA_HOME/bin/java etc. Near as I can see from the error is that it cannot access the -Djava.rmi.server.codebase.
Line: -----
app.serverimpl.service.ServiceException:java.rmi.ServerException: RemoteException occurred in server thread; nested exception is:
java.rmi.UnmarshalException: error unmarshalling arguments; nested exception is:
java.lang.ClassNotFoundException: access to class loader denied
at sun.rmi.server.UnicastServerRef.oldDispatch(UnicastServerRef.java:419)
at sun.rmi.server.UnicastServerRef.dispatch(UnicastServerRef.java:267)
at sun.rmi.transport.Transport$1.run(Transport.java:177)
at java.security.AccessController.doPrivileged(Native Method)
at sun.rmi.transport.Transport.serviceCall(Transport.java:173)
at sun.rmi.transport.tcp.TCPTransport.handleMessages(TCPTransport.java:553)
at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run0(TCPTransport.java:808)
at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run(TCPTransport.java:667)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1110)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:603)
at java.lang.Thread.run(Thread.java:636)
at sun.rmi.transport.StreamRemoteCall.exceptionReceivedFromServer(StreamRemoteCall.java:273)
at sun.rmi.transport.StreamRemoteCall.executeCall(StreamRemoteCall.java:251)
at sun.rmi.server.UnicastRef.invoke(UnicastRef.java:377)
at sun.rmi.registry.RegistryImpl_Stub.bind(Unknown Source)
at app.serverimpl.service.LoginManagerServiceImpl.start(LoginManagerServiceImpl.java:52)
at app.serverimpl.service.ServiceAdapter.start(ServiceAdapter.java:96)
at app.serverimpl.service.ServiceManager.startup(ServiceManager.java:78)
at app.serverimpl.ServerStarter.main(ServerStarter.java:62)
Caused by: java.rmi.UnmarshalException: error unmarshalling arguments; nested exception is:
java.lang.ClassNotFoundException: access to class loader denied
at sun.rmi.registry.RegistryImpl_Skel.dispatch(Unknown Source)
at sun.rmi.server.UnicastServerRef.oldDispatch(UnicastServerRef.java:409)
at sun.rmi.server.UnicastServerRef.dispatch(UnicastServerRef.java:267)
at sun.rmi.transport.Transport$1.run(Transport.java:177)
at java.security.AccessController.doPrivileged(Native Method)
at sun.rmi.transport.Transport.serviceCall(Transport.java:173)
at sun.rmi.transport.tcp.TCPTransport.handleMessages(TCPTransport.java:553)
at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run0(TCPTransport.java:808)
at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run(TCPTransport.java:667)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1110)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:603)
at java.lang.Thread.run(Thread.java:636)
Caused by: java.lang.ClassNotFoundException: access to class loader denied
at sun.rmi.server.LoaderHandler.loadClass(LoaderHandler.java:445)
at sun.rmi.server.LoaderHandler.loadClass(LoaderHandler.java:182)
at java.rmi.server.RMIClassLoader$2.loadClass(RMIClassLoader.java:637)
at java.rmi.server.RMIClassLoader.loadClass(RMIClassLoader.java:264)
at sun.rmi.server.MarshalInputStream.resolveClass(MarshalInputStream.java:214)
at java.io.ObjectInputStream.readNonProxyDesc(ObjectInputStream.java:1592)
at java.io.ObjectInputStream.readClassDesc(ObjectInputStream.java:1513)
at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1749)
at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1346)
at java.io.ObjectInputStream.readObject(ObjectInputStream.java:368)
... 12 more
Caused by: java.security.AccessControlException: access denied (java.io.FilePermission /usr/local/app/app/common/lib/- read)
at java.security.AccessControlContext.checkPermission(AccessControlContext.java:393)
at java.security.AccessController.checkPermission(AccessController.java:553)
at java.lang.SecurityManager.checkPermission(SecurityManager.java:549)
at sun.rmi.server.LoaderHandler$Loader.checkPermissions(LoaderHandler.java:1173)
at sun.rmi.server.LoaderHandler$Loader.access$000(LoaderHandler.java:1127)
at sun.rmi.server.LoaderHandler.loadClass(LoaderHandler.java:409)
... 21 more
Line: -----
Out of growing desperation (and since it's a test VM in virtual box so I'm not really protecting anything) I've already granted full permissions to everyone for these these files in the filesystem itself - chmod -R 775 - and I've made sure that common.jar is accessible. I also double-checked the Security Policy, Djava.security.policy, and that's just a straight all permission to everything (again, I'm not protecting anything on this test).
Line: -----
grant {
permission java.security.AllPermission;
Line: -----
What's really driving me nuts is that this exact same code is already running and working on another machine. There are no environment variables that I'm missing, and I don't see how those would relate to this problem even if I did. The directories are identical, and I've verified the location that's listed as the cause (/usr/local/app/app/common/lib/) exists and is accessible. I keep coming back to the file permissions and the security policy and I'm sure I could be missing something obvious, but I am not seeing it at all. Can anyone give me some advice on this?
I'm running a VM in VirtualBox 4.1.4, running CentOS 5.7 32-bit. Java is JDK 1.6.0, just the basic yum install package.

This is a .policy file problem, not a filesystem permissions problem. Run it with -Djava.security.debug=access,failure to see exactly what is going on. Basically your .policy file either doesn't grant the required FilePermission or isn't being loaded.
NB a codebase of a local JAR file isn't going to work unless all the clients are in the same host.

RMI server error under Linux

Hi all,
I'm not excatly sure, whether this is the right forum. Anyway, my problem is this:
I've written a JApplet that calls several methods over RMI. The RMI server is up and running properly. Most of the functions work well. One that initializes a JTree, however, causes problems. I get the following error message and I am stumped:
java.rmi.ServerError: Error occurred in server thread; nested exception is:
     java.lang.InternalError: Can't connect to X11 window server using ':0.0' as the value of the DISPLAY variable.
     at sun.rmi.server.UnicastServerRef.dispatch(UnicastServerRef.java:289)
     at sun.rmi.transport.Transport$1.run(Transport.java:148)
     at java.security.AccessController.doPrivileged(Native Method)
     at sun.rmi.transport.Transport.serviceCall(Transport.java:144)
     at sun.rmi.transport.tcp.TCPTransport.handleMessages(TCPTransport.java:460)
     at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run(TCPTransport.java:701)
     at java.lang.Thread.run(Thread.java:536)
     at sun.rmi.transport.StreamRemoteCall.exceptionReceivedFromServer(StreamRemoteCall.java:247)
     at sun.rmi.transport.StreamRemoteCall.executeCall(StreamRemoteCall.java:223)
     at sun.rmi.server.UnicastRef.invoke(UnicastRef.java:133)
     at de.uni_mannheim.wifo2.mlearning.portal.ServerFunctions_Stub.buildStructure(Unknown Source)
     at de.uni_mannheim.wifo2.mlearning.portal.CourseHandlerC.initialize(CourseHandlerC.java:68)
     at de.uni_mannheim.wifo2.mlearning.portal.MobilUM.actionPerformed(MobilUM.java:641)
     at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:1764)
     at javax.swing.AbstractButton$ForwardActionEvents.actionPerformed(AbstractButton.java:1817)
     at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:419)
     at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:257)
     at javax.swing.AbstractButton.doClick(AbstractButton.java:289)
     at javax.swing.plaf.basic.BasicMenuItemUI.doClick(BasicMenuItemUI.java:1109)
     at javax.swing.plaf.basic.BasicMenuItemUI$MouseInputHandler.mouseReleased(BasicMenuItemUI.java:943)
     at java.awt.Component.processMouseEvent(Component.java:5093)
     at java.awt.Component.processEvent(Component.java:4890)
     at java.awt.Container.processEvent(Container.java:1566)
     at java.awt.Component.dispatchEventImpl(Component.java:3598)
     at java.awt.Container.dispatchEventImpl(Container.java:1623)
     at java.awt.Component.dispatchEvent(Component.java:3439)
     at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:3450)
     at java.awt.LightweightDispatcher.processMouseEvent(Container.java:3165)
     at java.awt.LightweightDispatcher.dispatchEvent(Container.java:3095)
     at java.awt.Container.dispatchEventImpl(Container.java:1609)
     at java.awt.Component.dispatchEvent(Component.java:3439)
     at java.awt.EventQueue.dispatchEvent(EventQueue.java:450)
     at java.awt.EventDispatchThread.pumpOneEventForHierarchy(EventDispatchThread.java:197)
     at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:150)
     at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:144)
     at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:136)
     at java.awt.EventDispatchThread.run(EventDispatchThread.java:99)
Caused by: java.lang.InternalError: Can't connect to X11 window server using ':0.0' as the value of the DISPLAY variable.
     at sun.awt.X11GraphicsEnvironment.initDisplay(Native Method)
     at sun.awt.X11GraphicsEnvironment.<clinit>(X11GraphicsEnvironment.java:125)
     at java.lang.Class.forName0(Native Method)
     at java.lang.Class.forName(Class.java:140)
     at java.awt.GraphicsEnvironment.getLocalGraphicsEnvironment(GraphicsEnvironment.java:62)
     at java.awt.Font.initializeFont(Font.java:309)
     at java.awt.Font.<init>(Font.java:345)
     at javax.swing.plaf.metal.DefaultMetalTheme$FontDelegate.getFont(DefaultMetalTheme.java:195)
     at javax.swing.plaf.metal.DefaultMetalTheme.getFont(DefaultMetalTheme.java:153)
     at javax.swing.plaf.metal.DefaultMetalTheme.getUserTextFont(DefaultMetalTheme.java:137)
     at javax.swing.plaf.metal.MetalLookAndFeel$FontActiveValue.createValue(MetalLookAndFeel.java:1405)
     at javax.swing.UIDefaults.getFromHashtable(UIDefaults.java:196)
     at javax.swing.UIDefaults.get(UIDefaults.java:126)
     at javax.swing.MultiUIDefaults.get(MultiUIDefaults.java:44)
     at javax.swing.UIDefaults.getFont(UIDefaults.java:346)
     at javax.swing.UIManager.getFont(UIManager.java:491)
     at javax.swing.plaf.basic.BasicTreeUI.installDefaults(BasicTreeUI.java:596)
     at javax.swing.plaf.basic.BasicTreeUI.installUI(BasicTreeUI.java:530)
     at javax.swing.plaf.metal.MetalTreeUI.installUI(MetalTreeUI.java:86)
     at javax.swing.JComponent.setUI(JComponent.java:449)
     at javax.swing.JTree.setUI(JTree.java:551)
     at javax.swing.JTree.updateUI(JTree.java:567)
     at javax.swing.JTree.<init>(JTree.java:522)
     at javax.swing.JTree.<init>(JTree.java:498)
     at javax.swing.JTree.<init>(JTree.java:481)
     at de.uni_mannheim.wifo2.mlearning.portal.ServerFunctions.buildStructure(ServerFunctions.java:237)
     at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
     at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
     at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
     at java.lang.reflect.Method.invoke(Method.java:324)
     at sun.rmi.server.UnicastServerRef.dispatch(UnicastServerRef.java:261)
     at sun.rmi.transport.Transport$1.run(Transport.java:148)
     at java.security.AccessController.doPrivileged(Native Method)
     at sun.rmi.transport.Transport.serviceCall(Transport.java:144)
     at sun.rmi.transport.tcp.TCPTransport.handleMessages(TCPTransport.java:460)
     at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run(TCPTransport.java:701)
     at java.lang.Thread.run(Thread.java:536)
The entire system had been tested under a Windows XP environment and works without a glitch. Now I've installed the exact same system under unix and this happens!
If anyone has an idea I would be very grateful!
Kind regards,
Falk

Hi again,
alternately I get another error doing the excat same thing:
java.rmi.ServerError: Error occurred in server thread; nested exception is:
     java.lang.NoClassDefFoundError
     at sun.rmi.server.UnicastServerRef.dispatch(UnicastServerRef.java:289)
     at sun.rmi.transport.Transport$1.run(Transport.java:148)
     at java.security.AccessController.doPrivileged(Native Method)
     at sun.rmi.transport.Transport.serviceCall(Transport.java:144)
     at sun.rmi.transport.tcp.TCPTransport.handleMessages(TCPTransport.java:460)
     at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run(TCPTransport.java:701)
     at java.lang.Thread.run(Thread.java:536)
     at sun.rmi.transport.StreamRemoteCall.exceptionReceivedFromServer(StreamRemoteCall.java:247)
     at sun.rmi.transport.StreamRemoteCall.executeCall(StreamRemoteCall.java:223)
     at sun.rmi.server.UnicastRef.invoke(UnicastRef.java:133)
     at de.uni_mannheim.wifo2.mlearning.portal.ServerFunctions_Stub.buildStructure(Unknown Source)
     at de.uni_mannheim.wifo2.mlearning.portal.CourseHandlerC.initialize(CourseHandlerC.java:68)
     at de.uni_mannheim.wifo2.mlearning.portal.MobilUM.actionPerformed(MobilUM.java:641)
     at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:1764)
     at javax.swing.AbstractButton$ForwardActionEvents.actionPerformed(AbstractButton.java:1817)
     at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:419)
     at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:257)
     at javax.swing.AbstractButton.doClick(AbstractButton.java:289)
     at javax.swing.plaf.basic.BasicMenuItemUI.doClick(BasicMenuItemUI.java:1109)
     at javax.swing.plaf.basic.BasicMenuItemUI$MouseInputHandler.mouseReleased(BasicMenuItemUI.java:943)
     at java.awt.Component.processMouseEvent(Component.java:5093)
     at java.awt.Component.processEvent(Component.java:4890)
     at java.awt.Container.processEvent(Container.java:1566)
     at java.awt.Component.dispatchEventImpl(Component.java:3598)
     at java.awt.Container.dispatchEventImpl(Container.java:1623)
     at java.awt.Component.dispatchEvent(Component.java:3439)
     at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:3450)
     at java.awt.LightweightDispatcher.processMouseEvent(Container.java:3165)
     at java.awt.LightweightDispatcher.dispatchEvent(Container.java:3095)
     at java.awt.Container.dispatchEventImpl(Container.java:1609)
     at java.awt.Component.dispatchEvent(Component.java:3439)
     at java.awt.EventQueue.dispatchEvent(EventQueue.java:450)
     at java.awt.EventDispatchThread.pumpOneEventForHierarchy(EventDispatchThread.java:197)
     at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:150)
     at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:144)
     at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:136)
     at java.awt.EventDispatchThread.run(EventDispatchThread.java:99)
Caused by: java.lang.NoClassDefFoundError
     at java.lang.Class.forName0(Native Method)
     at java.lang.Class.forName(Class.java:140)
     at java.awt.GraphicsEnvironment.getLocalGraphicsEnvironment(GraphicsEnvironment.java:62)
     at java.awt.Font.initializeFont(Font.java:309)
     at java.awt.Font.<init>(Font.java:345)
     at javax.swing.plaf.metal.DefaultMetalTheme$FontDelegate.getFont(DefaultMetalTheme.java:195)
     at javax.swing.plaf.metal.DefaultMetalTheme.getFont(DefaultMetalTheme.java:153)
     at javax.swing.plaf.metal.DefaultMetalTheme.getUserTextFont(DefaultMetalTheme.java:137)
     at javax.swing.plaf.metal.MetalLookAndFeel$FontActiveValue.createValue(MetalLookAndFeel.java:1405)
     at javax.swing.UIDefaults.getFromHashtable(UIDefaults.java:196)
     at javax.swing.UIDefaults.get(UIDefaults.java:126)
     at javax.swing.MultiUIDefaults.get(MultiUIDefaults.java:44)
     at javax.swing.UIDefaults.getFont(UIDefaults.java:346)
     at javax.swing.UIManager.getFont(UIManager.java:491)
     at javax.swing.plaf.basic.BasicTreeUI.installDefaults(BasicTreeUI.java:596)
at javax.swing.plaf.basic.BasicTreeUI.installUI(BasicTreeUI.java:530)
     at javax.swing.plaf.metal.MetalTreeUI.installUI(MetalTreeUI.java:86)
     at javax.swing.JComponent.setUI(JComponent.java:449)
     at javax.swing.JTree.setUI(JTree.java:551)
     at javax.swing.JTree.updateUI(JTree.java:567)
     at javax.swing.JTree.<init>(JTree.java:522)
     at javax.swing.JTree.<init>(JTree.java:498)
     at javax.swing.JTree.<init>(JTree.java:481)
     at de.uni_mannheim.wifo2.mlearning.portal.ServerFunctions.buildStructure(ServerFunctions.java:237)
     at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
     at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
     at java.lang.reflect.Method.invoke(Method.java:324)
     at sun.rmi.server.UnicastServerRef.dispatch(UnicastServerRef.java:261)
     at sun.rmi.transport.Transport$1.run(Transport.java:148)
     at java.security.AccessController.doPrivileged(Native Method)
     at sun.rmi.transport.Transport.serviceCall(Transport.java:144)
     at sun.rmi.transport.tcp.TCPTransport.handleMessages(TCPTransport.java:460)
     at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run(TCPTransport.java:701)
     at java.lang.Thread.run(Thread.java:536)
Thanks again!

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