persistent Database Change Notifications

I need to monitor an oracle table for changes and I'm trying to choose between Database Change Notifications and Advanced Queuing.

I don't understand certain points in Database JDBC Developer's Guide and getDatabaseChangeRegistration javadoc

If I register a DB change registration (DCR) with the NTF_QOS_RELIABLE flag, I expect the notifications to persist while my jdbc application is down. However, I don't see a way to restore existing DCR after my app restarts: according to javadoc, getDatabaseChangeRegistration() is only for PLSQL listeners. And it seems that jdbc DCRs are destroyed when my app dies and I don't even have to unregister them.

After my program restarts I sometimes get notifications with a previous registration id. It is not necessary to call stmt.setDatabaseChangeRegistration() every time I start my app.

I never receive changes that happened while my app was down and this is the biggest problem. What does NTF_QOS_RELIABLE do then?

package org.foo;

import static oracle.jdbc.OracleConnection.*;

import java.sql.DriverManager;
import java.sql.ResultSet;
import java.util.Locale;
import java.util.Properties;

import oracle.jdbc.OracleConnection;
import oracle.jdbc.OracleStatement;
import oracle.jdbc.dcn.DatabaseChangeEvent;
import oracle.jdbc.dcn.DatabaseChangeListener;
import oracle.jdbc.dcn.DatabaseChangeRegistration;

// CHECKSTYLE.OFF: Name|Reg
public final class TestDbListener {

    private TestDbListener() {}

    public static void main(final String[] args) throws Exception {
        Locale.setDefault(Locale.US);

        Class.forName("oracle.jdbc.OracleDriver");
        final OracleConnection conn =
                (OracleConnection) DriverManager.getConnection(
                        "jdbc:oracle:thin:@192.168.56.150:1521:xe", "scott", "tiger");

        final Properties props = new Properties();
        props.setProperty(NTF_QOS_RELIABLE, "true");

        final DatabaseChangeRegistration dcr = conn.registerDatabaseChangeNotification(props);
        final DCNListener list = new DCNListener();
        dcr.addListener(list);

        if (true) {

            // now you need to add whatever tables you want to monitor
            final OracleStatement stmt = (OracleStatement) conn.createStatement();
            // associate the statement with the registration:
            stmt.setDatabaseChangeRegistration(dcr);

            final String sql = "select * from a where 1=2";
            final ResultSet rs = stmt.executeQuery(sql);

        }

        final String[] tableNames = dcr.getTables();
        for (int i = 0; i < tableNames.length; i++) {
            System.out.println(tableNames[i] + " has been registered.");
        }

        Thread.sleep(1000000);

        // rs.close();

    }

}

class DCNListener implements DatabaseChangeListener {

    @Override
    public void onDatabaseChangeNotification(final DatabaseChangeEvent event) {
        System.out.println("onDatabaseChangeNotification: " + event);
    }
}

SQL:

-- sysdba: 
-- grant change notification to scott;

-- scott:
create table a ( a int );

insert into a values ( 1 );
commit;