🚀 go-pugleaf

On 8/14/2003 at 9:39:18 AM, Oliver Young wrote:

> java.lang.NoClassDefFoundError: dory2/StopDory
>  at java.lang.ClassLoader.defineClass0(Native Method)
>  at java.lang.ClassLoader.defineClass(ClassLoader.java:502)
>  at
> java.security.SecureClassLoader.defineClass(SecureClassLoader.java:123
> )  at java.net.URLClassLoader.defineClass(URLClassLoader.java:250)
> at java.net.URLClassLoader.access$100(URLClassLoader.java:54)  at
> java.net.URLClassLoader$1.run(URLClassLoader.java:193)  at
> java.security.AccessController.doPrivileged(Native Method)  at
> java.net.URLClassLoader.findClass(URLClassLoader.java:186)  at
> java.lang.ClassLoader.loadClass(ClassLoader.java:299)  at
> java.lang.ClassLoader.loadClass(ClassLoader.java:292)  at
> sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:265)  at
> java.lang.ClassLoader.loadClass(ClassLoader.java:255)  at
> java.lang.ClassLoader.loadClassInternal(ClassLoader.java:315)
> Exception in thread "main"
> 
>     when compiling with:
> 
> String name = "rmi://localhost:1099/dory2.StopDoryEngine";
> StopDoryEngine rmi = new StopDoryEngine();
> Naming.rebind(name, rmi);
> 
>     exception occurs after compilation and before app enters "main"
> method.  What is this?

What seems to be happening is that the application ClassLoader is
trying to load the dory2.StopDory class.  It does not find it on the
class path so it is trying to load it from the RMI codebase.

The reason this is happening before your main program runs is probably
because you have a class (static) variable initialization that requires
the class to be loaded.

-- 
Regards,

John McGrath  [TeamB]

> What seems to be happening is that the application ClassLoader is
> trying to load the dory2.StopDory class.
dory2.StopDory is an interface not a class.

"Oliver Young" <no@spam.please> writes:

> dory2.StopDory is an interface not a class.

The main difference between an interface and a class is a flag: They
both come from class files and need to be resolved by the ClassLoader.

> What seems to be happening is that the application ClassLoader is
> trying to load the dory2.StopDory class.  It does not find it on the
> class path so it is trying to load it from the RMI codebase.
Well, it should load it from RMI, that is why I'm using RMI.

> The reason this is happening before your main program runs is probably
> because you have a class (static) variable initialization that requires
> the class to be loaded.
Could you, please, tell me what to do? I'm not fluent with RMI.

On 8/18/2003 at 1:13:28 AM, Oliver Young wrote:

> > What seems to be happening is that the application ClassLoader is
> > trying to load the dory2.StopDory class.

> dory2.StopDory is an interface not a class.

In this context, it does not make any difference.  Just substitute
"interface" for "class" in my message and it is still accurate.

In Java, the term "class" is often used to include interfaces.  Take
the class "ClassLoader" for example.  A ClassLoader loads both classes
and interfaces.  Perhaps it would be more accurate to call it something
like "ClassAndInterfaceLoader" or "NonPrimitiveTypeLoader", but they
chose the shorter name instead.

-- 
Regards,

John McGrath  [TeamB]

On 8/18/2003 at 6:04:35 AM, Oliver Young wrote:

> > What seems to be happening is that the application ClassLoader is
> > trying to load the dory2.StopDory class.  It does not find it on the
> > class path so it is trying to load it from the RMI codebase.
> Well, it should load it from RMI, that is why I'm using RMI.
> 
> > The reason this is happening before your main program runs is
> > probably because you have a class (static) variable initialization
> > that requires the class to be loaded.
> Could you, please, tell me what to do? I'm not fluent with RMI.

If you want the classes to be loaded from the RMI codebase, you have to
install a SecurityManager, normally an RMISecurityManager.  I presumed
you were doing this, but I should mention this because you did not show
that in the code snippet you posted.

You also need to make sure that the RMISecurityManager is installed
*before* your program tries to load a class from the RMI codebase.
This is more of a Java Language issue than an RMI issue.

Your main class needs to be loaded before the main method can be run
and when that happens, all static initializers are evaluated and all
static blocks are executed.  This occurs *before* your main method is
run.

I presume your code declares and initializes a static variable of one
of your own class types.  This causes that class to be loaded before
the main() method runs.  All you need to do is to move the
initialization.  You can initialize the variable in the main() method,
after the RMI Security Manager is installed.

-- 
Regards,

John McGrath  [TeamB]

    Thank you for your help.

> If you want the classes to be loaded from the RMI codebase, you have to
> install a SecurityManager, normally an RMISecurityManager.  I presumed
> you were doing this, but I should mention this because you did not show
> that in the code snippet you posted.
>
> You also need to make sure that the RMISecurityManager is installed
> *before* your program tries to load a class from the RMI codebase.
> This is more of a Java Language issue than an RMI issue.
Well, I did not have RMISecurityManager, so I added it but it did not
changed anything. Also, I've found one small RMI example and it didn't had
RMISecurityManager too, but it is working fine on my PC. So, my question is:
in which cases I need RMISecurityManager? This is how I installes securitiy
manager according to the Sun's RMI tutorial:

if (System.getSecurityManager() == null) {
  System.setSecurityManager(new RMISecurityManager());
}

> Your main class needs to be loaded before the main method can be run
> and when that happens, all static initializers are evaluated and all
> static blocks are executed.  This occurs *before* your main method is
> run.
>
> I presume your code declares and initializes a static variable of one
> of your own class types.  This causes that class to be loaded before
> the main() method runs.  All you need to do is to move the
> initialization.  You can initialize the variable in the main() method,
> after the RMI Security Manager is installed.
The only static method or variable in my project is main() method in my app.

I've added entry to the java.policy file as stated in Sun's RMI tutorial but
it didn't changed anything:
grant {
    permission java.net.SocketPermission "*:1024-65535",
        "connect,accept";
    permission java.net.SocketPermission "*:80", "connect";
};Here is source code of my class, I've removed everything irrelevant for
RMI and same exception still occurs:package dory2;import
java.security.*;import java.security.cert.*;import java.rmi.*;import
java.rmi.server.*;public class DoryMain {  private boolean doExecute = true;
//This method below should be called as remote procedure  public void
stopDory() {    System.out.println("Dory stopped.");    doExecute = false;
return;  }  public DoryMain() {    if (System.getSecurityManager() == null)
{      System.setSecurityManager(new RMISecurityManager());    }    String
name = "rmi://localhost:1099/StopDory";    try {        StopDoryIntf rmi =
new StopDoryEngine(this);        Naming.rebind(name, rmi);
System.out.println("StopDoryEngine bound");    } catch (Exception e)
{        System.err.println("StopDoryEngine exception: " +
e.getMessage());        e.printStackTrace();    }    while (doExecute) {
//do something before someone calls stopDory from the outside (of my
)    }  }  public static void main(String[] args) {    DoryMain dm = new
DoryMain();  }}This is interface:package dory2;import java.rmi.*;public
interface StopDoryIntf extends Remote {  public void stopDory() throws
RemoteException;}And this class:package dory2;import java.rmi.*;import
java.rmi.server.*;public class StopDoryEngine extends UnicastRemoteObject
implements StopDoryIntf{    private DoryMain dory = null;    public
StopDoryEngine() throws RemoteException {        super();        if
(System.getSecurityManager() == null) {
System.setSecurityManager(new RMISecurityManager());        }    }    public
StopDoryEngine(DoryMain dory) throws RemoteException {      if
(System.getSecurityManager() == null) {        System.setSecurityManager(new
RMISecurityManager());      }      this.dory = dory;    }    public void
stopDory() {      dory.stopDory();    }}The exception
is:java.lang.NoClassDefFoundError: dory2/StopDoryIntf at
java.lang.ClassLoader.defineClass0(Native Method) at
java.lang.ClassLoader.defineClass(ClassLoader.java:502) at
java.security.SecureClassLoader.defineClass(SecureClassLoader.java:123) at
java.net.URLClassLoader.defineClass(URLClassLoader.java:250) at
java.net.URLClassLoader.access$100(URLClassLoader.java:54) at
java.net.URLClassLoader$1.run(URLClassLoader.java:193) at
java.security.AccessController.doPrivileged(Native Method) at
java.net.URLClassLoader.findClass(URLClassLoader.java:186) at
java.lang.ClassLoader.loadClass(ClassLoader.java:299) at
java.lang.ClassLoader.loadClass(ClassLoader.java:292) at
sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:265) at
java.lang.ClassLoader.loadClass(ClassLoader.java:255) at
java.lang.ClassLoader.loadClassInternal(ClassLoader.java:315)Exception in
thread "main"

Something strange happend with source code formatting so I'm reposting it:

Here is source code of my class, I've removed everything irrelevant for
RMI and same exception still occurs:

package dory2;
import java.security.*;
import java.security.cert.*;
import java.rmi.*;
import java.rmi.server.*;

public class DoryMain {
  private boolean doExecute = true;
  //This method below should be called as remote procedure
  public void stopDory() {
    System.out.println("Dory stopped.");
    doExecute = false;
    return;
  }

  public DoryMain() {
    if (System.getSecurityManager() == null) {
      System.setSecurityManager(new RMISecurityManager());
    }

    String name = "rmi://localhost:1099/StopDory";
    try {
      StopDoryIntf rmi = new StopDoryEngine(this);
      Naming.rebind(name, rmi);
      System.out.println("StopDoryEngine bound");
    } catch (Exception e) {
      System.err.println("StopDoryEngine exception: " + e.getMessage());
      e.printStackTrace();
    }

    while (doExecute) {
  //do something before someone calls stopDory from the outside (of my app)
    }
  }

  public static void main(String[] args) {
    DoryMain dm = new DoryMain();
  }

}

This is interface:

package dory2;

import java.rmi.*;

public interface StopDoryIntf extends Remote {
  public void stopDory() throws RemoteException;
}

And this class:

package dory2;

import java.rmi.*;
import java.rmi.server.*;

public class StopDoryEngine extends UnicastRemoteObject implements
StopDoryIntf{
  private DoryMain dory = null;

  public StopDoryEngine() throws RemoteException {
    super();

    if (System.getSecurityManager() == null) {
      System.setSecurityManager(new RMISecurityManager());
    }
  }

  public StopDoryEngine(DoryMain dory) throws RemoteException {
    if (System.getSecurityManager() == null) {
      System.setSecurityManager(new RMISecurityManager());
    }
    this.dory = dory;
  }

  public void stopDory() {
    dory.stopDory();
  }

}

The exception is:

java.lang.NoClassDefFoundError: dory2/StopDoryIntf at
java.lang.ClassLoader.defineClass0(Native Method) at
java.lang.ClassLoader.defineClass(ClassLoader.java:502) at
java.security.SecureClassLoader.defineClass(SecureClassLoader.java:123) at
java.net.URLClassLoader.defineClass(URLClassLoader.java:250) at
java.net.URLClassLoader.access$100(URLClassLoader.java:54) at
java.net.URLClassLoader$1.run(URLClassLoader.java:193) at
java.security.AccessController.doPrivileged(Native Method) at
java.net.URLClassLoader.findClass(URLClassLoader.java:186) at
java.lang.ClassLoader.loadClass(ClassLoader.java:299) at
java.lang.ClassLoader.loadClass(ClassLoader.java:292) at
sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:265) at
java.lang.ClassLoader.loadClass(ClassLoader.java:255) at
java.lang.ClassLoader.loadClassInternal(ClassLoader.java:315)Exception in
thread "main"

I can't understand this:

This peace of code executes *before* any other code in my app (before main()
or code in a front of code block below):

StopDoryIntf rmi = new StopDoryEngine(this);
Naming.rebind(name, rmi);

Although this peace of the code is in the middle of constructor. (?) If I
put "System.out.println("test");" before this block of the code "test" will
not be printed and previously mentioned exception will occur (it can't be
cougth with try/catch block). If I comment block above then executing starts
from the main() and there is no exception. This behavior (start executing
code from the middle of the procedure) is not very common for modern
languges such as VB, Object Pascal (Delphi), C/C++...

Any comments?

    Maybe I've found it. Interface and "stub" class are in the same package
as my app. I tried to move it into it's own package but that didn't worked
too. Where I should put them?

    Well, I've fixed it and now it is working very well. I'm happy. :) I did
not add interface into .jar that I was deploying to the RMI server...

On 8/19/2003 at 7:01:55 AM, Oliver Young wrote:

> Well, I've fixed it and now it is working very well. I'm happy.

That is good to hear.

-- 
Regards,

John McGrath  [TeamB]