Question

Scenario:
I’m implementing an RMI example between 2 PCs where the Controller PC queries the Agent PC for information. The agent PC may run Xen or KVM , hence the implementations of the queries differ(Reason for using RMI).
On the Agent’s side I’m running 2 RMI registries bound to two different ports. When the same example is carried out with just 1 Registry on the agent’s side, everything works fine.

Here is my code:
Controller. java(contains main() on controller’s side):

public class Controller {

NetworkDiscovery n;
public static int discoveryInterval=2000;
static public PM pmlist;

public static void main(String[] args) throws UnknownHostException,NotBoundException, `   MalformedURLException, RemoteException {

pmOperations pm=(pmOperations)Naming.lookup("rmi://Agent_IP/RMIService1");
boolean l= pm.CreateVM("apple3","/var/lib/libvirt/images",1,200);
System.out.println(l);

vmOperations vm=(vmOperations)Naming.lookup("rmi://Agent_IP/RMIService2");
boolean ShutdownVM = vm.ShutdownVM("apple1");
System.out.println(ShutdownVM);
//other code
}

pmOperations.java(on controller’s side)(on the agent’s side, it has the same defn with implementation code inside function)

public interface pmOperations extends java.rmi.Remote{
    public boolean CreateVM(String vmName,String imgSrc, int allotCPU, int allotMem )
    throws java.rmi.RemoteException;
}

vmOperations.java(on controller’s side)(on the agent’s side, it has the same defn with implementation code inside function)

public interface vmOperations extends java.rmi.Remote{
    boolean ChangeVMParam(String vmName,String paramName,String paramValue)
    throws java.rmi.RemoteException;
}

Agent.java

public class Agent {

Agent() throws RemoteException, MalformedURLException{
    Registry RMIService1 = LocateRegistry.createRegistry(1099);

    Registry RMIService2 = LocateRegistry.createRegistry(4478);

        vmOperations vmOp = new kvmVM();
        pmOperations pmOp = new kvmPM();

      Naming.rebind("rmi://localhost:1099/RMIService1", pmOp);
      Naming.rebind("rmi://localhost:4478/RMIService2", vmOp);
}

public static void main(String[] args) throws SocketException, UnknownHostException, IOException, LibvirtException {

        System.out.println("Inside main ");
        new Agent();
        //other code
}
}

Error I get while running above code on controller’s side-no error on agent side:

Exception in thread “main” java.rmi.NotBoundException: RMIService2
at sun.rmi.registry.RegistryImpl.lookup(RegistryImpl.java:106)
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: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:359)
at sun.rmi.registry.RegistryImpl_Stub.lookup(Unknown Source)
at java.rmi.Naming.lookup(Naming.java:84)
at package1.Controller.main(Controller.java:43)

Thanks!

Answer 1

You can’t create two Registries in the same JVM.
You don’t need two Registries in the same host.
You don’t need to create two instances of the remote object.

Just create one Registry, one remote object, and bind it to the Registry twice, once with each name. You don’t really need to bind it twice either really either. There’s a lot of pointless duplication in this design.