Integration of RapidMiner in Java application

I have a text classification process in RapidMiner. It reads the test data from specified excel ssheet and does the classification. I have also a small Java application which is just running this process. Now I want to make the file input part in my aplication, so that everytime I would be able to specify the excel file from my application (not from RapidMiner). Any hints?

This is the code:

import com.rapidminer.RapidMiner;
import com.rapidminer.Process;
import com.rapidminer.example.Attribute;
import com.rapidminer.example.Example;
import com.rapidminer.example.ExampleSet;
import com.rapidminer.operator.IOContainer;
import com.rapidminer.operator.Operator;
import com.rapidminer.operator.OperatorException;



import java.io.File;
import java.io.IOException;
import java.util.Iterator;
import com.rapidminer.operator.io.ExcelExampleSource; 
import com.rapidminer.tools.XMLException;


public class Classification {

    public static void main(String [] args) throws Exception{
         ExampleSet resultSet1 = null;
         IOContainer ioInput = null;
        IOContainer ioResult;
        try {
            RapidMiner.setExecutionMode(RapidMiner.ExecutionMode.COMMAND_LINE);
            RapidMiner.init();
            Process pr = new Process(new File("C:\Users\MP-TEST\Desktop\Rapid_Test\Wieder_Model.rmp"));
            Operator op = pr.getOperator("Read Excel");
            op.setParameter(ExcelExampleSource.PARAMETER_EXCEL_FILE, "C:\Users\MP-TEST\Desktop\Rapid_Test\HaendlerRatings_neu.xls");
            ioResult = pr.run(ioInput);
            if (ioResult.getElementAt(0) instanceof ExampleSet) {
                resultSet1 = (ExampleSet)ioResult.getElementAt(0);

                for (Example example : resultSet1) {
                    Iterator<Attribute> allAtts = example.getAttributes().allAttributes();
                    while(allAtts.hasNext()) {
                        Attribute a = allAtts.next();
                                if (a.isNumerical()) {
                                        double value = example.getValue(a);
                                        System.out.println(value);

                                } else {
                                        String value = example.getValueAsString(a);
                                        System.out.println(value);
                                }
                         }
                }
                    }
        } catch (IOException | XMLException | OperatorException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }




          }
}

This is the error:

Apr 09, 2013 9:06:05 AM com.rapidminer.Process run
INFO: Process C:UsersMP-TESTDesktopRapid_TestWieder_Model.rmp starts
com.rapidminer.operator.UserError: A value for the parameter 'excel_file' must be specified! 
    at com.rapidminer.operator.nio.model.ExcelResultSetConfiguration.makeDataResultSet(ExcelResultSetConfiguration.java:316)
    at com.rapidminer.operator.nio.model.AbstractDataResultSetReader.createExampleSet(AbstractDataResultSetReader.java:127)
    at com.rapidminer.operator.io.AbstractExampleSource.read(AbstractExampleSource.java:52)
    at com.rapidminer.operator.io.AbstractExampleSource.read(AbstractExampleSource.java:1)
    at com.rapidminer.operator.io.AbstractReader.doWork(AbstractReader.java:126)
    at com.rapidminer.operator.Operator.execute(Operator.java:855)
    at com.rapidminer.operator.execution.SimpleUnitExecutor.execute(SimpleUnitExecutor.java:51)
    at com.rapidminer.operator.ExecutionUnit.execute(ExecutionUnit.java:711)
    at com.rapidminer.operator.OperatorChain.doWork(OperatorChain.java:379)
    at com.rapidminer.operator.Operator.execute(Operator.java:855)
    at com.rapidminer.Process.run(Process.java:949)
    at com.rapidminer.Process.run(Process.java:873)
    at com.rapidminer.Process.run(Process.java:832)
    at com.rapidminer.Process.run(Process.java:827)
    at Classification.main(Classification.java:29)

Best regards

Armen