rmi class can not found exception

Question

I wrote an simple project using java rmi and exported to an executable jar file. When I tries to run it, sometimes i got exceptions and sometimes it works. When I specify -Djava.rmi.server.codebase=file:serverClasses/, it seems it didn't create the jar file correctly. Here is the stacktrace:

java.rmi.ServerException: RemoteException occurred in server thread; nested exception is: 
    java.rmi.UnmarshalException: error unmarshalling arguments; nested exception is: 
    java.lang.ClassNotFoundException: com.ServerBootstrap.IServer
    at sun.rmi.server.UnicastServerRef.oldDispatch(UnicastServerRef.java:413)
    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.rebind(Unknown Source)
    at java.rmi.Naming.rebind(Naming.java:177)
    at com.v3q6.eece411.A2.ServerBootstrap.ChatRoomServer.main(ChatRoomServer.java:37)
Caused by: java.rmi.UnmarshalException: error unmarshalling arguments; nested exception is: 
    java.lang.ClassNotFoundException: com.ServerBootstrap.IServer
    at sun.rmi.registry.RegistryImpl_Skel.dispatch(Unknown Source)
    at sun.rmi.server.UnicastServerRef.oldDispatch(UnicastServerRef.java:403)
    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: com.ServerBootstrap.IServer
    at java.net.URLClassLoader$1.run(URLClassLoader.java:217)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(URLClassLoader.java:205)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:323)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:268)
    at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:336)
    at java.lang.Class.forName0(Native Method)
    at java.lang.Class.forName(Class.java:264)
    at sun.rmi.server.LoaderHandler.loadProxyInterfaces(LoaderHandler.java:728)
    at sun.rmi.server.LoaderHandler.loadProxyClass(LoaderHandler.java:672)
    at sun.rmi.server.LoaderHandler.loadProxyClass(LoaderHandler.java:609)
    at java.rmi.server.RMIClassLoader$2.loadProxyClass(RMIClassLoader.java:646)
    at java.rmi.server.RMIClassLoader.loadProxyClass(RMIClassLoader.java:311)
    at sun.rmi.server.MarshalInputStream.resolveProxyClass(MarshalInputStream.java:255)
    at java.io.ObjectInputStream.readProxyDesc(ObjectInputStream.java:1548)
    at java.io.ObjectInputStream.readClassDesc(ObjectInputStream.java:1510)
    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

It seems the program doesn't recognize the codebase. In my case, all the files are local. Does anyone know what is the problem? thanks

Answer 1

Try explicitly specifying the name of the JAR file containing the com.ServerBootstrap.IServer class in your codebase, e.g.

-Djava.rmi.server.codebase=file:serverClasses/myjarfile.jar

The "Dynamic code downloading using JavaTM RMI (Using the java.rmi.server.codebase Property)" doc provides more information on the use of codebase and the options for its specification.