Object passed to RMI Server

Question

Hello
I have a function in the RMI client that passes an object to the RMI server. The server updates one of the members of this object.
When I try to get this memebr from the client, I get 0.
This is the Object code:
public class Progress implements Serializable {
          private static final long     serialVersionUID     = 8168473416653301292L;
                    private int mProgress = 0;
    /** Creates a new instance of Progress */
    public Progress() {
    public int getProgress()
        return mProgress;
    public void setProgress(int progress)
              System.out.println("progress = "+progress);
        mProgress = progress;
}This is the function that passes the Object to the server:
          public RequestResult executeAdminAPI(int aDbTypeOrdinal, String aHost, int aPort, String aUser, String aPassword,
                              String aInput, Progress progress) throws RMIClientException, SCException {
                    try {
                              if (mServerInitialised)
                                        return mJNICommRMIServer.executeAdminAPIWrapper(aDbTypeOrdinal, aHost, aPort, aUser, aPassword, aInput, progress);
                              else {
                                        synchronized (mServerInitializedMutex) {
                                                  return mJNICommRMIServer.executeAdminAPIWrapper(aDbTypeOrdinal, aHost, aPort, aUser, aPassword, aInput, progress);
                    catch (RemoteException e) {
                              // We'll restart the server on JNIFatalException
                              // means that we should kill the process and restart it
                              // JNIFatalException means that the cpp code send an error code which
                              // We don't restart the server on SocketTimeOut like the other functions,
                              // because this function may take a long time to execute
                              if (e.detail instanceof JNIFatalException) {
                                        restartServer("executeAdminAPI got an exception: " + e.detail.getMessage());
                              if ((e.detail instanceof ConnectException)) // RMI-TODO check perhaps it
                                        // should be restartServer()
                                        startServer("executeAdminAPI got an exception: " + e.detail.getMessage());
                              if (e.detail instanceof JNIException)
                                        throw new SCException(((JNIException) (e.detail)).getErrorCode(), ((JNIException) (e.detail)).getErrorMessage());
                              else
                                        throw new RMIClientException(e);
          }The "setProgress" (called by the server) prints the correct numbers, but the "getProgress" (called by the client) returns 0.
Can anyone explain please?
Thanks,
Libby

Answer 1

Arguments are passed by value in RMI unless they are exported remote objects. So the update took place at the server only. If you want it reflected at the client, either (i) return the updated object as the result of the method, or (ii) make the updatable object an exported remote object, i.e. a callback. But note that (ii) doesn't play with firewals in place.