I am running a RMI application and no security manager: RMI class loader disabled exception comes

java eclipse-plugin classpath rmi rmiregistry
pcc picture pcc · Jun 27, 2013 · Viewed 18.3k times · Source

This is the whole exception:

Computeappengine exceptionRemoteException occurred in server thread; nested exception is: 
java.rmi.UnmarshalException: error unmarshalling arguments; nested exception is: 
java.lang.ClassNotFoundException: Client.prog (no security manager: RMI class loader disabled)
java.rmi.ServerException: RemoteException occurred in server thread; nested exception is: 
java.rmi.UnmarshalException: error unmarshalling arguments; nested exception is: 
java.lang.ClassNotFoundException: Client.prog (no security manager: RMI class loader disabled)
at sun.rmi.server.UnicastServerRef.dispatch(UnicastServerRef.java:334)
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:662)
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:142)
at Engine.ComputeappEngine_Stub.executeTask(Unknown Source)
at Client.computeappprog.main(computeappprog.java:23)
Caused by: java.rmi.UnmarshalException: error unmarshalling arguments; nested exception is: 
java.lang.ClassNotFoundException: Client.prog (no security manager: RMI class loader disabled)
at sun.rmi.server.UnicastServerRef.dispatch(UnicastServerRef.java:294)
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:662)
Caused by: java.lang.ClassNotFoundException: Client.prog (no security manager: RMI class loader disabled)
at sun.rmi.server.LoaderHandler.loadClass(LoaderHandler.java:373)
at sun.rmi.server.LoaderHandler.loadClass(LoaderHandler.java:163)
at java.rmi.server.RMIClassLoader$2.loadClass(RMIClassLoader.java:620)
at java.rmi.server.RMIClassLoader.loadClass(RMIClassLoader.java:247)
at sun.rmi.server.MarshalInputStream.resolveClass(MarshalInputStream.java:197)
at java.io.ObjectInputStream.readNonProxyDesc(ObjectInputStream.java:1574)
at java.io.ObjectInputStream.readClassDesc(ObjectInputStream.java:1495)
at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1731)
at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1328)
at java.io.ObjectInputStream.readObject(ObjectInputStream.java:350)
at sun.rmi.server.UnicastRef.unmarshalValue(UnicastRef.java:306)
at sun.rmi.server.UnicastServerRef.dispatch(UnicastServerRef.java:288)
... 9 more

My client package contains two classes Computeappproj which contains main also and prog

I already searched 1000 of forums. Nothing helped.

Hoping for something positive

and good

may be...

Answer

Jk1 picture Jk1 · Jun 27, 2013

The problem actualy lies in a classloading. When you're transferring some non-jdk objects (i.e. objects of your own classes) via RMI you need to ensure, that both JVMs, client and server, has your custom class in a classpath. In your case server lacks Client.prog class, so it's unable to reconstruct an object from binary representation - Client.prog class bytecode is necessary for that. There are generally two ways to resolve this issue:

  1. Easy one: copy all your data transfer object classes to both client's and servers's classpath. So none of them will be confused with unknown classes. For a somewhat serious you might even want to create a separate JAR with DTO classes for the ease of maintenance.

  2. Challenging one: enable remote classloading. In short, this technique enables your server to download class bytecode from a client and vice versa, if necessary. This option has a clear security issue (dowloading potentialy unsafe code), so it's disabled by default. To enable it you should use -Djava.rmi.server.codebase property with URL defined and set an appropriate classloader (RMIClassloader or it's descendant) to make Java security system happy. Here's the useful link with some background theory and troubleshooting guide: link

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