RMI Class Loader

Hi, i Have an application which uses RMI and I need to change at runtime the codebase property to point to a local directory which is not on the CLASSPATH environment variable, so the JVM default Class Loader cannot load the classes located at that local directory. I guess I have to define my own subclass of the class java.rmi.server.RMIClassLoaderSpi and in my code I should change the property "java.rmi.server.RMIClassLoaderSpi" with the method System.setProperty() to point to another RMIClassLoaderSpi subclass as needed, right?
I found the documentation of the class RMIClassLoaderSpi too vague. Can anyone tell me what code to place on which of her methods? An example would be great.

I would suggest another simple approach - launch a new VM for every user application.
I looked at the RMI implementation (you can also download the J2SDK source code and see how internal sun.* classes are implemented) and it looks like you will get the correct codebase annotation if you load your user classes with a URLClassLoader.
Now if you want to use a dynamic codebase property you can have your own RMIClassLoaderSpi. It has a method "getClassAnnotation" which you can implement to return any codebase you wish for your classes.
Genady

Similar Messages

No security manager: RMI class loader disabled

i tried to add a filter to my client jmx
my filter is:
class Filter implements NotificationFilter {
public boolean isNotificationEnabled(Notification n) {
          return (n.getType().equals("example.user.remove"))
          ? true
          : false;
in my client i use:
Filter filter=new Filter();
Listener listener=new Listener();
mbeanServer.addNotificationListener(mbeanName, listener, filter, null);
if i dont put the filter(if i use null) my client works but when i include the filter I have this error:
java.rmi.UnmarshalException: java.lang.ClassNotFoundException: Filter (no security manager: RMI class loader disabled); nested exception is:
     java.lang.ClassNotFoundException: Filter (no security manager: RMI class loader disabled)
what is wrong?

You need to make sure that Filter.class is on your classpath, either directly as the .class file or in a JAR file that is on the classpath.

No security manager: RMI class loader disabled Error at RMI client programm

Got following error on invoking remote method from RMI client,
java.rmi.UnmarshalException: error unmarshalling return; nested exception is:
java.lang.ClassNotFoundException: com.rmi.RmiImpl_Stub (no security manager: RMI class loader disabled)
Please let me know solution.

Hello JAAZ,
I got the same error yesterday. I was a little frustrated, because the day before everything was fine...
java.rmi.UnmarshalException: error unmarshalling return; nested exception is:
java.lang.ClassNotFoundException: uk.co.it.ete.server.ETE_Server (no security manager: RMI class loader disabled)
at sun.rmi.registry.RegistryImpl_Stub.lookup(Unknown Source)The solution was, that I did some refactoring and some of the classes were now in different packages. I updated the system on the client-side and now everything works again.
I think debugging RMI-applications is not as easy as "normal" applications ..
maybe this helps..
Regards
tk

ERROR: RMI Class loader disabled

Despite of setting classpath, policy tool I am getting following error. What does the error mean and What is the solution?
E:\Javaprog\RMI>java MultiplyServerImpl
Server could not start java.rmi.ServerException: RemoteException occurred in server thread; nested exception is:
java.rmi.UnmarshalException: error unmarshalling arguments; nested exception is:
java.lang.ClassNotFoundException: MultiplyServerImpl_Stub (no security manager: RMI class loader disabled)

Hello JAAZ,
I got the same error yesterday. I was a little frustrated, because the day before everything was fine...
java.rmi.UnmarshalException: error unmarshalling return; nested exception is:
java.lang.ClassNotFoundException: uk.co.it.ete.server.ETE_Server (no security manager: RMI class loader disabled)
at sun.rmi.registry.RegistryImpl_Stub.lookup(Unknown Source)The solution was, that I did some refactoring and some of the classes were now in different packages. I updated the system on the client-side and now everything works again.
I think debugging RMI-applications is not as easy as "normal" applications ..
maybe this helps..
Regards
tk

Simple RMI/IIOP app : "no security manager: RMI class loader disabled"

Hello colleagues!
I do not understand the problem at all, and asking for your kind help.
This is my first code for RMI/IIOP. We are using JBoss as application server.
What I've done :
1) created test.Command interface , extending Remote
2) created test.CommandImpl , implementing above mentioned interface and java.io.Serializable, and extending javax.rmi.PortableRemoteObject.
BTW, Serializable is not implemented in some tutorials, but absence of Serializable causes NotSerializableException when trying to rebind (next step).
3) in server code, created initial context and called
context.rebind("test/Command",new CommandImpl());
4) Ran rmic -iiop test.CommandImpl . A result was two new cass files, CommandImplTie.class and CommandStub.class , both are also in package "test".
5) Created remote client and put CommandStub.class to client
classpath (under package "test", too).
6) In client code, initialized the context and called
context.lookup("test/Command").
On this line (lookup), the following exception is being raised :
javax.naming.CommunicationException. Root exception is java.lang.ClassNotFoundException: test.CommandImpl (no security manager: RMI class loader disabled)
     at sun.rmi.server.LoaderHandler.loadClass(LoaderHandler.java:368)
     at sun.rmi.server.LoaderHandler.loadClass(LoaderHandler.java:161)
     at java.rmi.server.RMIClassLoader$2.loadClass(RMIClassLoader.java:631)
     at java.rmi.server.RMIClassLoader.loadClass(RMIClassLoader.java:257)
     at sun.rmi.server.MarshalInputStream.resolveClass(MarshalInputStream.java:200)
     at java.io.ObjectInputStream.readNonProxyDesc(ObjectInputStream.java:1513)
     at java.io.ObjectInputStream.readClassDesc(ObjectInputStream.java:1435)
     at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1626)
     at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1274)
     at java.io.ObjectInputStream.readObject(ObjectInputStream.java:324)
     at java.rmi.MarshalledObject.get(MarshalledObject.java:135)
     at org.jnp.interfaces.MarshalledValuePair.get(MarshalledValuePair.java:30)
     at org.jnp.interfaces.NamingContext.lookup(NamingContext.java:514)
     at org.jnp.interfaces.NamingContext.lookup(NamingContext.java:471)
     at javax.naming.InitialContext.lookup(InitialContext.java:347)
Is _Stub class all that client needs from server classes, to obtain
the reference ? I tried to put _Tie also to client, but with the same result.
All Jndi paths to JBoss server are correct, as I've used them successfully in other applications.
Many thanks in advance,
Daniel

Next few words to the topic.
I made tests with canonical RMI/IIOP tutorial from Sun.
When I use Sun's ORB (orbd.exe) , everything work fine. I started
orbd on the same PC as JBoss, and client and server are running
remotely.
But with JBoss ORB, I have the same exception as described above.
Server starts and registers in JNDI successfully, but client can not
obtain a remote reference. Exception is being thrown on
context.lookup().
So the difference is definitely in security managers for two ORBs.
I also tried to create new RMISecurityMananger and set it, but with
no effect.
Any ideas ?
TIA,
Daniel.

RMI Dynamic Class Loading

Hello,
I have a standalone Java Client which is connecting to an RMI based svr component on WLS 6.0sp1. However, before connecting to the RMI Svr, I am trying to boot strap couple of other CLASS files from the App Svr. using the RMIClassLoader. Now here's the problem...
I have placed my classes( one which I want to download and instantiate before I start making conventional calls to RMI Svr remote methods) in the folder WL_HOME/config/examples/rmi/*.class
which is the code_base url I use. However, the error I get when trying to download the classs using RMIClass loader is:
No Security Manager: RMI Class Loader disabled"...
due to which I can not even get connected to my remote object after that. Can somebody please tell me how can I set whatever option it is so that I can get this thing working.
I tried using the "Grant all" security policy too on the client side & server side in vain.
Any help is truly appreciated. Thanks a lot!
cl I am trying to

I'll try having a crack at this, see inline comments
Chirag Shah wrote:
Hello,
I have a standalone Java Client which is connecting to an RMI based svr component on WLS 6.0sp1. However, before connecting to the RMI Svr, I am trying to boot strap couple of other CLASS files from the App Svr. using the RMIClassLoader. Now here's the problem...
I have placed my classes( one which I want to download and instantiate before I start making conventional calls to RMI Svr remote methods) in the folder WL_HOME/config/examples/rmi/*.class
which is the code_base url I use. However, the error I get when trying to download the classs using RMIClass loader is:I'll assume that you're using a proper URL (file://) to instanciate your ClassLoader.
>
No Security Manager: RMI Class Loader disabled"...
Does your client explicitly set a SecurityManager using the following command?
if (System.getSecurityManager() == null) {
System.setSecurityManager(new java.rmi.RMISecurityManager());
Also,I believe that it should only be your client changing its policy file (for the network classload).
>
due to which I can not even get connected to my remote object after that. Can somebody please tell me how can I set whatever option it is so that I can get this thing working.
I tried using the "Grant all" security policy too on the client side & server side in vain.
Any help is truly appreciated. Thanks a lot!
cl I am trying toHope it helps,
Stephane Vaucher
CIRANO
Research Professional

RMI and the class loader delegation model

Hello,
I need to know what the class loader delagation chain looks like when RMI does dynamic class loading. What is the RMIClassLoader's parent? Does it delegate to Thread.currentThread().getContextClassLoader()?
In a test application I can debug the chain which looks like this:
sun.misc.Launcher$AppClassLoader@bac748
sun.misc.Launcher$ExtClassLoader@7172ea
The AppClassLoader is the class loader for the test and is coincident with getSystemClassLoader(). Its parent is the ExtClassLoader which I believe is in charge of loading anything from jre/lib/ext. But I don't know how to get a reference to the RMIClassLoader in order to find out what it's parent is.
I would appreciate any info on this.
Thanks in advance,
Joe

Well that was easy.
I just used the RMIClassLoader.getClassLoader(String codebase) and was able to determine the chain.
FYI: the chian is as follows:
ExtClassLoader <-- AppClassLoader <-- sun.rmi.server.LoaderHandler
Of interest, if you have a custom class loader its parent will most likely be the AppClassLoader but the rmi class loader will not chain off of your custom class loader. It does some interesting things in order for this to work. It will look for custom class loader to load interfaces but will use the RMIClassLoader to load stubs. Pretty cool.
Thanks anyway.
Joe

Is Dynamic Class Loading(RMI) Possible in EJB?

In Java RMI,it allows dynamic class loading,that is when the stub and interface class files are modified by the server,the client side can download the updated stub and inteface classes.
As the remote interface of EJB extends Javax.ejb.EJBObject which in turn extends java.rmi.remote.Also the Home interface of EJB extends
javax.ejb.EJBHome which also extends java.rmi.remote.
Therefore I wonder if EJB also supports dynamic class
loading as RMI does.If yes,how to do so?Is it the responsibility of the Application Servers and transparent
to client? If No,then is this a defect in EJB??
Thank you very much in advance!!
John

This would be done by the container and is transparent to the client. Most app servers support "hot deploy" where you can deploy beans while the server is running. This requires dynamic class loading.

Dynamic Class Loading (RMI)

Hi,
i have my rmi server, implementing objects,stubs and skeleton classes deployed in my Tomcat server and they are stored under the tomcat root folder.
In anoather jvm iam trying to load the classes thru the below code.
java -Djava.rmi.server.codebase=http://ssd8/tomcat-3.2.4/install_dir/webapps/ROOT/WEB-INF/rmicode stockMarketClient
ssd8 is the hostname(machine) which contains all my rmi server files.
and stockmarketclient is my rmi client.
Iam getting the java.lang.noclassdeffound error.
what may be the problem???
Should i have the security policy file in the client machine.

Please Do tell me if any of the following worked I'll be greatly obliged
1) Try this
java -Djava.rmi.server.codebase=http://servername/dir1/dir2/ RMIServer
This / thing at the end of the URL is very important
2) This is how I did it just Today
Dynamic Class Loading Using RMI
     Server Side
1) Main Interface
2) Implementing Class
3) Stub & Skel                    (RMI Server & Web Server)
4) All Other Classes used by the Server
     Web Server Side
1) Main Interface
2) Stub & Skel                    (RMI Server & Web Server)
3) All Other Classes (not Main Client Class)
     Client Side
1) Main Interface
2) Main Client Class
3) Stubs
4) Security Manager
     RUNNING
SERVER
     java DataServerImpl
CLIENT
     java DataClient xyz
Note
Make Calls as follows
System.setSecurityManager(new LaxSecurityManager());
DataServer server = (DataServer) Naming.lookup("rmi://localhost:1099/DataServer");
Runnable r = (Runnable)server.getNewClass();
r.run();
DON'T make Calls as follows
System.setSecurityManager(new LaxSecurityManager());
DataServer server = (DataServer) Naming.lookup("rmi://localhost:1099/DataServer");
NewClass obj = server.getNewClass();
obj.run();
if done as above provide the Class NewClass to the Client as well ( whole purpose defeated)
Code
     // SecurityManager
import java.rmi.*;
import java.security.*;
public class LaxSecurityManager extends RMISecurityManager
     // All Checks are routed through this method
     public void checkPermission(Permission p)
          // do nothing
     // Main Interface
import java.rmi.*;
public interface DataServer extends Remote
     public boolean login(String usr_name,char[] pass_wrd) throws RemoteException;
     public Object getNewClass() throws RemoteException;
     // Main Server
import java.rmi.*;
import java.rmi.server.*;
import java.rmi.registry.*;
public class DataServerImpl /*extends UnicastRemoteObject*/ implements DataServer
     static
          try
               LocateRegistry.createRegistry(1099);
          catch(Exception e)
               System.err.println("Static " + e);
     public boolean login(String usr_name,char[] pass_wd) throws RemoteException
          System.out.println("Welcome " + usr_name);
          if( pass_wd == null || pass_wd.length == 0 || pass_wd.length > 10 )
               return false;
          return true;
     public Object getNewClass() throws RemoteException
          System.out.println("Returning New Class");
          return new NewClass();
     public DataServerImpl() throws RemoteException
          try
               System.setProperty("java.rmi.server.codebase","http://localhost:8080/");
               UnicastRemoteObject.exportObject(this);
               Naming.rebind("DataServer",this);
          catch(java.net.MalformedURLException e)
               System.err.println("DataServerImpl " + e);
               return;
          System.out.println("Server Registered");
     public static void main(String[] args) throws Exception
          new DataServerImpl();
     // Class Moving Around the Network
public class NewClass implements java.io.Serializable,Runnable
     int num;
     public void run()
          System.out.println("Start the Server with Number = " + num);
     public NewClass()
          num = (int)(Math.random()*1000);
     public String toString()
          return num + "";
     // Client
import java.rmi.*;
public class DataClient
     public static void main(String[] args) throws Exception
          System.setSecurityManager(new LaxSecurityManager());
          String pass = new String();
          if(args.length == 0)
               System.err.println("usage: java DataClient PassWord");
               System.exit(1);
          else
               pass = args[0];
          DataServer server = (DataServer) Naming.lookup("rmi://localhost:1099/DataServer");
          Runnable r = (Runnable)server.getNewClass();
          r.run();
All the Best

Access to class loader RMI

Hello,
I am writing an RMI-chat program, but I have some problems using dynamic class loading.
I do set my security manager, I've got a java.policy, use the right commandline-options, but I get the following error when I try to dynamicly load a class. The class is on the right server, and the server is running, and properly set in the codebase:
ClassNotFoundException: access to class loader denied.
Can anyone please help me?
Johanna

Sorry,
I was using two codebases, and one was not accesible in the policy file.
My bad

Dynamic class loading over a network

hi,
Im tryin to run a simple little "Hello World" type app using RMI. What i want to know is what permissions i need to grant inorder to dynamically load (client side) the stubs and skeletons from my server. Currently i get an UnmarshalException with a nested ClassNotFoundException and the helpful message "access denied to class loader". Any help is appreciated.
Thanks in advance,
Alex

It is hard to tell what the problem is with out a stack trace from the exception. Perhaps in the future you would be kind enough to supply one.

Dynamic class loading failed, why?

Hi there!
We are using WebLogic 5.1 togehter with Apache1.3.22/Tomcat4.01. It all worked
fine for about 2 month. All of a sudden, dynamic class loading refuses to work.
From one day to the other I got the excpetion: javax.naming.CommunicationException.
Root exception is weblogic.rmi.UnmarshalException: Unmarshalling return
- with nested exception:
[java.lang.ClassNotFoundException: class com.dsh.egb.aks.betrieb.ejbs.AnmeldenEJBHomeImpl_ServiceStub
previously not found]
Why does this happen? I can not remember having touched any properties.
Please help,
Heiner

If you were relying on client network classloading stubs from WebLogic, you
can test if it still works by pointing your browser to
htpp://yourweblogic:7001/classes/com/dsh/egb/aks/betrieb/ejbs/AnmeldenEJBHomeImpl_ServiceStub.class
Heiner Amthauer <[email protected]> wrote:
Hi there!
We are using WebLogic 5.1 togehter with Apache1.3.22/Tomcat4.01. It all worked
fine for about 2 month. All of a sudden, dynamic class loading refuses to work.
From one day to the other I got the excpetion: javax.naming.CommunicationException.
Root exception is weblogic.rmi.UnmarshalException: Unmarshalling return
- with nested exception:
[java.lang.ClassNotFoundException: class com.dsh.egb.aks.betrieb.ejbs.AnmeldenEJBHomeImpl_ServiceStub
previously not found]
Why does this happen? I can not remember having touched any properties.
Please help,
Heiner--
Dimitri

Dynamic class loading when CODEBASE is unreachable. A bug?

Let us suppose that we have a large-scale distributed application with ca. 1000 participants communicating via RMI and utilizing dynamic class loading. As we all know, a HTTP code server must be available for this purpose in order to provide dynamically downloaded code, usually the communication proxy code of remote objects. In a real-world scenario, the HTTP server will never be 100% available, so that we will have cases that a Java process will not be able to download the necessary Java classes, causing the RMI communication to fail with a ClassNotFoundException or similar exception. In such a case, a robust application would perform some recovery activities and retry the remote call. Eventually, the HTTP server becomes available again and the distributed system recovers automatically. This seems to work fine with J2SE 1.4.2_10, but not with 1.4.2_11 and newer versions. Considering Java 5, the Update 9 exhibits the same problem.
For tracking down the problem, I've written a simple distributed test application, consisting of a client and a server. A server listens on a port, and sends a MarshalledObject to the client. The code of the MarshalledObject is annotated with the value of the "java.rmi.server.codebase" system property. The annotation contains an URL of the JAR file containing the code of the original object. The client connects to the server, reads data form the socket and unmarshalls the original object. This is basically the same procedure as when objects are accross the wire as arguments/return values/exceptions by the RMI/JRMP engine. This procedure is repeated forever in the loop. Due to the fact that the client's CLASSPATH doesn't contain the code of the original object, this code should dynamically be loaded from the HTTP server using the appropriate annotation provided by the server.
If we start the client while the HTTP server is down, the client will keep generating the ClassNotFoundException over and over again, as expected. So far, so good. If we now start the HTTP server while the client is still running, we will observe different behaviors, depending on the version of the client's JVM:
1. In J2SE 1.4.2_10, the client will download the code from the HTTP server and successfully unmarshal the original object sent by the server. ClassNotFoundExceptions will not be generated again.
2. In J2SE 1.4.2_11, 1.4.2_12 and 1.4.2_13 as well as in J2SE 5.0 Update 9, the client will continue generating ClassNotFoundExceptions. Analysis of the HTTP server's access log shows that there were no attempts to download the JAR file required for unmarshaling the object sent by the server.
It seems that in the newer JVM versions the RMI engine remembers URLs which have failed and does not attempt to access them anymore. Althogh this may have some advantages considering the overall network load, the dynamical class loading becomes practically useless in productive large distributed systems. The very first attempt to load the codebase of the communication peer must succeed, otherwise the whole process must be restarted for the communication to work, which is a very expensive (and for most customers unacceptable) operation in terms of preformance and resources usage.
Should this be seen as a bug or a feature of the JVM? What do you think?
Regards,
Miran
Here is the code to reproduce:
Server code
package server;
import java.net.*;
import java.rmi.*;
import java.io.*;
public class Server implements Serializable {
private int value = 42;
public Server() {
public String toString() {
    return "The Answer is " + value;
public static void main( String[] args ) {
    if( args.length!=1 ) {
      System.out.println( "Usage: server.Server <port>" );
      System.exit( 1 );
    try {
      MarshalledObject data = new MarshalledObject( new Server() );
      int port = Integer.parseInt( args[0] );
      ServerSocket serverSocket = new ServerSocket( port );
      System.out.println( "Accepting connections..." );
      while( true ) {
        Socket s = serverSocket.accept();
        new Thread( new SocketHandler( s, data ) ).start();
    } catch( Exception ex ) {
      ex.printStackTrace();
    System.exit( 0 );
public static class SocketHandler implements Runnable {
    private Socket s;
    private Serializable data;
    public SocketHandler( Socket s, Serializable data ) {
      this.s = s;
      this.data = data;
    public void run() {
      try {
        OutputStream os = s.getOutputStream();
        ObjectOutputStream oos = new ObjectOutputStream( os );
        oos.writeObject( data );
        oos.close();
        os.close();
        s.close();
        System.out.println( "Serving socket succeeded" );
      } catch( Exception ex ) {
        System.out.println( "Serving socket failed" );
        ex.printStackTrace();
Client code
package client;
import java.rmi.*;
import java.net.*;
import java.io.*;
public class Client {
public static void main( String[] args ) {
    if( args.length!=1 ) {
      System.out.println( "Usage: client.Client <port>" );
      System.exit( 1 );
    try {
      if( System.getSecurityManager()==null ) {
        System.setSecurityManager( new RMISecurityManager() );
      int port = Integer.parseInt( args[0] );
      for( int i = 1; true; ++i ) {
        try {
          Socket s = new Socket( "localhost", port );
          InputStream is = s.getInputStream();
          ObjectInputStream ois = new ObjectInputStream( is );
          Object o = ois.readObject();
          ois.close();
          is.close();
          s.close();
          Object umo = ((MarshalledObject) o).get();
          System.out.println( i + ". Retreiving MarshalledObject succeeded: "
                              + umo );
        } catch( Exception ex ) {
          System.out.println( i + ". Retreiving MarshalledObject failed" );
          ex.printStackTrace();
        System.out.println( i + ". Waiting for 10 sec" );
        Thread.sleep( 10000 );
    } catch( Exception ex ) {
      ex.printStackTrace();
    System.exit( 0 );
Start command for the server
java -cp server.jar -Djava.rmi.server.codebase="http://localhost/playground/server.jar" server.Server 33933
Start command for the client
java -cp client.jar -Djava.security.policy=all.policy client.Client 33933
The policy.all file should look as follows
// All permissions
grant {
   permission java.security.AllPermission;
};The server.jar file should only contain the classes from the server package. This file should also be made accessible via HTTP (e.g. by using the Apache HTTP server).
The client.jar file should only contain the classes from the client package.

no body know about this??

Dynamic Class Loading and Stubs

How Dynamic Class Loading is used on Java RMI, since stubs are generated on clients using Reflection API?
I was reading Dynamic code downloading using JavaTM RMI (http://java.sun.com/javase/6/docs/technotes/guides/rmi/codebase.html), it seems to be out of date.
For example, "The client requests the class definition from the codebase. The codebase the client uses is the URL that was annotated to the stub instance when the stub class was loaded by the registry. Back in step 1, the annotated stub for the exported object was then registered with the Java RMI registry bound to a name."

"Enhancements in J2SETM 5.0
Dynamic Generation of Stub Classes
This release adds support for the dynamic generation of stub classes at runtime, obviating the need to use the Java(tm) Remote Method Invocation (Java RMI) stub compiler, rmic, to pregenerate stub classes for remote objects. *Note that rmic must still be used to pregenerate stub classes for remote objects that need to support clients running on _earlier versions_.*
When an application exports a remote object (using the constructors or static exportObject methods(1) of the classes java.rmi.server.UnicastRemoteObject or java.rmi.activation.Activatable) and a pregenerated stub class for the remote object's class cannot be loaded, the remote object's stub will be a java.lang.reflect.Proxy instance (whose class is dynamically generated) with a java.rmi.server.RemoteObjectInvocationHandler as its invocation handler.
An existing application can be deployed to use dynamically generated stub classes unconditionally (that is, whether or not pregenerated stub classes exist) by setting the system property java.rmi.server.ignoreStubClasses to "true". If this property is set to "true", pregenerated stub classes are never used.
Notes:
* If a remote object has pre-5.0 clients, that remote object should use a stub class pregenerated with rmic or the client will get an ClassNotFoundException deserializing the remote object's stub. Pre-5.0 clients will not be able to load an instance of a dynamically generated stub class, because such a class contains an instance of RemoteObjectInvocationHandler, which was not available prior to this release.
* Prior to the J2SE 5.0 release, exporting a remote object would throw a java.rmi.StubNotFoundException if the pregenerated stub class for the remote object's class could not be loaded. With the added support for dynamically generated stub classes, exporting a remote object that has no pregenerated stub class will silently succeed instead. A user deploying a server application to support pre-5.0 clients must still make sure to pregenerate stub classes for the server's remote object classes, even though missing stub classes are no longer reported at export time. Such errors will instead be reported to a pre-5.0 client when it deserializes a dynamically generated stub class.
(1) The static method UnicastRemoteObject.exportObject(Remote) is declared to return java.rmi.server.RemoteStub and therefore cannot be used to export a remote object to use a dynamically generated stub class for its stub. An instance of a dynamically generated stub class is a java.lang.reflect.Proxy instance which is not assignable to RemoteStub."
http://java.sun.com/j2se/1.5.0/docs/guide/rmi/relnotes.html

Codebase classes loading on their own?

I have been tracking down a performance issue. So I am tracing the classes loaded by my clients VM. I have a class defined like so
public final class GraphicFactory implements IGraphicFactory, Serializable{
     private static final long serialVersionUID = 1L;
     public IDSComponentInstance createComponentInstance(Point location, Dimension size){
        if (location == null || size == null) {
            throw new NullPointerException();
        return new DBComponentInstance(location,size);
    public IDSFunctionConnection createFunctionConnection(Point sourceLocation, Point targetLocation) {
        if(sourceLocation == null || targetLocation == null){
            throw new NullPointerException();
        return new DBFunctionConnection(sourceLocation,targetLocation);
}I want to pass this class to the client. So the client calls a method, and this class is returned. When that happens, the client immediately loads this class via the codebase. The thing I can not see is when the client loads the "DBFunctionConnection" and "DBComponentInstance" classes. These classes are also in jar files which can be found by the codebase. Obviously the client is getting them because its working. And they are definitely coming from the server. But I do not see any log of them being loaded.
Its like they get loaded in secret. I bet they do too. I think classes loaded as a result of another class loading are not logged.
But at the same time, I thought a class would not be loaded until it is needed!? If its loading it right away, then this is a good thing because otherwise the RMI system could throw an exception at a most unusual place when the class gets loaded because a method is called.
I can't quite figure out what is happening here :(

I guess RMI classloader is just different.
From testing I can see that when the main class is
marshalled it seems as if the classes it contains are
also marshalled.RMIClassLoader is little more than a URLClassLoader. Classes are neither marshalled nor unmarshalled in RMI, they are loaded via the codebase mechanism, using whatever WEB or other protocol you define in the codebase URL.
The log is not telling me when classes are loaded,So you're logging the wrong thing?
So I am still stuck having a hard time knowing when
the RMI is transferring classes.RMI isn't transferring classes. The RMIClassLoader is transferring classes in response to class-loading requirements. This is completely separate from RMI marshalling. It is more strongly associated with RMI unmarshalling but these are still distinct operations.

RMI Class Loader

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