Client thread fails when contacting RMI server: java.rmi.UnmarshalException: error unmarshalling return

Question

I have a client side that takes input from a JSP page and then gives it to a thread, the thread is added to a thread pool and when it executes the thread contacts the RMI server to get the remote object and then should return the results which will be displayed on a new JSP page, the problem is once the runnable code is executed I get the following error:

java.rmi.UnmarshalException: error unmarshalling return; nested exception is: 
    java.lang.ClassNotFoundException: servertest.DictionaryInterface (no security manager: RMI class loader disabled)
    at sun.rmi.registry.RegistryImpl_Stub.lookup(Unknown Source)
    at java.rmi.Naming.lookup(Unknown Source)
    at Client.LookupWorker.run(LookupWorker.java:27)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
    at java.lang.Thread.run(Unknown Source)
Caused by: java.lang.ClassNotFoundException: servertest.DictionaryInterface (no security manager: RMI class loader disabled)
    at sun.rmi.server.LoaderHandler.loadProxyClass(Unknown Source)Thread didnt finish its job properly, error: java.lang.NullPointerException

Heres the Java code behind the JSP page

if (request.getParameter("word") != null) {
            String word = request.getParameter("word");
            String res;
            System.out.println("The word to find: "+word);

            // Get handle on our pool
            WorkerPool pool = WorkerPool.getInstance( );
            // Create Job
            LookupWorker wordWork = new LookupWorker(word);
            // Add job to pool
            res = pool.addJob(wordWork);
            request.getSession().setAttribute("result", res);
            response.sendRedirect("/SearchResults"); 
        }

Here is the thread class:

package Client;

import java.net.MalformedURLException;
import java.rmi.Naming;
import java.rmi.NotBoundException;
import java.rmi.RemoteException;

import DictionaryInterface.DictionaryInterface;

public class LookupWorker implements WorkerPlan {

    private String word;
    private String jobName;
    private String serverResult;
    private long threadId;

    public LookupWorker(String w) {
        super();
        this.word = w;
        jobName = "Lookup Job";
    }

    @Override
    public void run(){
        DictionaryInterface Dictonary = null;
        try {
            Dictonary = (DictionaryInterface) Naming.lookup("rmi://127.0.0.1:1099/DictionaryService");
        } catch (MalformedURLException | RemoteException | NotBoundException e1) {
            // TODO Auto-generated catch block
            e1.printStackTrace();
        }
        try {
            serverResult = Dictonary.lookup(word);
        } catch (RemoteException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
            System.out.println(serverResult); 
            threadId = Thread.currentThread().getId();
    }

    public String getServerResult() {
        return serverResult;
    }

    public String getWord() {
        return word;
    }

    public String getJobName() {
        return jobName;
    }

    @Override
    public String toString() {
        return jobName + " [Id= " + threadId + "word= " + word + ", serverResult= " + serverResult + "]";
    }   

}

The pool code involded in executing the thread:

public String addJob(WorkerPlan job) {
        String result;
        threadCounter++;
        // Adding new lookup job to our queue
        System.out.println("Adding a " + job.getJobName() + " to the queue. Searching for: " + job.getWord() + " Job number: " + threadCounter);
        executor.execute(job);
        try {
            Thread.sleep(5000);
        } catch (InterruptedException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } // sleep so we can wait for rmi object to come in
        System.out.println(job.toString());
        result = job.getServerResult();
        return result;
    }

Ive tried different paths for the VM arguments but cant get it to work, any help is greatly appreciated.

user207421 · Accepted Answer · 2017-12-19T23:31:11.633

Client thread fails when contacting RMI server:

No. It fails when looking up the RMI Registry. See the stack trace.

java.rmi.UnmarshalException: error unmarshalling return

See the stack trace. The underlying error is

java.lang.ClassNotFoundException: servertest.DictionaryInterface (no security manager: RMI class loader disabled)

You haven't deployed this class to the client. You seem to have both servertest.DictionaryInterface and DictionaryInterface.DictionaryInterface. You can't do that. The package names have to be the same at both ends.

Client thread fails when contacting RMI server: java.rmi.UnmarshalException: error unmarshalling return

1 Answers1