running rmi server, classnotfound

Question

Hi I'm trying to run a java application that binds a class to the naming server, but i constantly get a ClassNotFoundException

First I start the registry:

rmiregistry

then from eclipse I try to execute the server but get this error

java.rmi.ServerException: RemoteException occurred in server thread; nested exception is: java.rmi.UnmarshalException: error unmarshalling arguments; nested exception is: java.lang.ClassNotFoundException: progInternet2008.commons.NominabileFactory at sun.rmi.server.UnicastServerRef.oldDispatch(UnicastServerRef.java:396) at sun.rmi.server.UnicastServerRef.dispatch(UnicastServerRef.java:250) at sun.rmi.transport.Transport$1.run(Transport.java:159) at java.security.AccessController.doPrivileged(Native Method) at sun.rmi.transport.Transport.serviceCall(Transport.java:155) at sun.rmi.transport.tcp.TCPTransport.handleMessages(TCPTransport.java:535) at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run0(TCPTransport.java:790) at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run(TCPTransport.java:649) at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908) at java.lang.Thread.run(Thread.java:619) at sun.rmi.transport.StreamRemoteCall.exceptionReceivedFromServer(StreamRemoteCall.java:255) at sun.rmi.transport.StreamRemoteCall.executeCall(StreamRemoteCall.java:233) at sun.rmi.server.UnicastRef.invoke(UnicastRef.java:359) at sun.rmi.registry.RegistryImpl_Stub.rebind(Unknown Source) at progInternet2008.Pozzobon.tesi.Slave.main(Slave.java:54) Caused by: java.rmi.UnmarshalException: error unmarshalling arguments; nested exception is: java.lang.ClassNotFoundException: progInternet2008.commons.NominabileFactory at sun.rmi.registry.RegistryImpl_Skel.dispatch(Unknown Source) at sun.rmi.server.UnicastServerRef.oldDispatch(UnicastServerRef.java:386) at sun.rmi.server.UnicastServerRef.dispatch(UnicastServerRef.java:250) at sun.rmi.transport.Transport$1.run(Transport.java:159) at java.security.AccessController.doPrivileged(Native Method) at sun.rmi.transport.Transport.serviceCall(Transport.java:155) at sun.rmi.transport.tcp.TCPTransport.handleMessages(TCPTransport.java:535) at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run0(TCPTransport.java:790) at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run(TCPTransport.java:649) at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908) at java.lang.Thread.run(Thread.java:619) Caused by: java.lang.ClassNotFoundException: progInternet2008.commons.NominabileFactory at java.net.URLClassLoader$1.run(URLClassLoader.java:200) at java.security.AccessController.doPrivileged(Native Method) at java.net.URLClassLoader.findClass(URLClassLoader.java:188) at java.lang.ClassLoader.loadClass(ClassLoader.java:307) at java.lang.ClassLoader.loadClass(ClassLoader.java:252) at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:320) at java.lang.Class.forName0(Native Method) at java.lang.Class.forName(Class.java:247) at sun.rmi.server.LoaderHandler.loadProxyInterfaces(LoaderHandler.java:711) at sun.rmi.server.LoaderHandler.loadProxyClass(LoaderHandler.java:655) at sun.rmi.server.LoaderHandler.loadProxyClass(LoaderHandler.java:592) at java.rmi.server.RMIClassLoader$2.loadProxyClass(RMIClassLoader.java:628) at java.rmi.server.RMIClassLoader.loadProxyClass(RMIClassLoader.java:294) at sun.rmi.server.MarshalInputStream.resolveProxyClass(MarshalInputStream.java:238) at java.io.ObjectInputStream.readProxyDesc(ObjectInputStream.java:1531) at java.io.ObjectInputStream.readClassDesc(ObjectInputStream.java:1493) at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1732) at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1329) at java.io.ObjectInputStream.readObject(ObjectInputStream.java:351) ... 12 more

I've read the RMI Java tutorial but still could not get it working...

As VM Arguments I've set this:

-Djava.rmi.server.codebase=file:${workspace_loc}/progInternet2008

please help me

(I'm using Java 6)

Answer 1

I'm fairly certain that you'll have to start your RMI server using the same classpath as your application. I believe it takes the same parameters as java, i.e. -cp [your class path].

Answer 2

Okay I just overcame this problem. Make sure when you run rmiregistry, that your classpath environment variable is set.

for example you might have a script:

set CLASSPATH=[path to jdbc driver].jar
rmiregistry.exe

This was all i needed to get my lost classpath working. I'm not sure how to send -cp commandline to the rmiregistry.exe. Its documentation is quite lacking.

Answer 3

The exception is occurring because the rmiregistry application doesn't know where to load classes from. When you attempt to bind an object in the RMI registry, the registry downloads the class definition for that object. Some of the other answers are telling you to get around this by setting the classpath for the rmiregistry app so that it has the class definitions when it is started and doesn't need to download anything, but Sun's Java RMI tutorial explicitly says not to do this. I suspect this has the potential to cause conflicts between the version of the class in the registry and the class on the server.

The correct way to handle the problem is to set the java.rmi.server.codebase property as you were trying to do. The property requires that a directory path be terminated with a forward slash, like so:

-Djava.rmi.server.codebase=file:${workspace_loc}/progInternet2008/

You may also be having trouble if the ${workspace_loc} variable is a relative path and the rmiregistry application was not started in the same directory so the relative path is not correct for it. If you either make the path absolute, or start the rmiregistry in the appropriate directory, the ClassNotFoundException should go away. See the tutorial on the java.rmi.server.codebase property for a little more detailed information.