WalkerSourceApplet.java

/*
 * Created on Feb 5, 2004
 *
 * A RBNB source that generates numbers in a bounded random walk.
 */

package org.nees.rbnb;

import java.applet.Applet;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
 
import com.rbnb.sapi.*;
import COM.Creare.Utility.ArgHandler; //for argument parsing
import COM.Creare.Utility.RBNBProcess; //alternative to System.exit, so
                                       //don't bring down servlet engine

public class WalkerSourceApplet extends Applet {

    SimpleRandomWalk base = new SimpleRandomWalk();
    
    private static final String SERVER_NAME = "localhost";
    private static final String SERVER_PORT = "3333";
    private static final String SOURCE_NAME = "RandomWalk";
    private static final String CHANNEL_NAME = "RandomWalkData";
    private static final long TIMER_INTERVAL=1000;
    
    private String serverName = SERVER_NAME;
    private String serverPort = SERVER_PORT;
    private String server = serverName + ":" + serverPort;
    private String sourceName = SOURCE_NAME;
    private String channelName = CHANNEL_NAME;
    private long timerInterval = TIMER_INTERVAL;
         
    Source source = null;
    ChannelMap sMap;
    int index;
    boolean connected = false;
    
    Thread timerThread;
    boolean runit = false;
    
    private void setArgs() {
        String serverName = SERVER_NAME;
        String serverPort = SERVER_PORT;
        String sourceName = SOURCE_NAME;
        String channelName = CHANNEL_NAME;
        String timerString = "" + TIMER_INTERVAL;
        String param;

        param = getParameter("serverName");
        if (param != null)
            serverName = param;
        
        param = getParameter("serverPort");
        if (param != null)
            serverPort = param;
        
        param = getParameter("source");
        if (param != null)
            sourceName = param;

        param = getParameter("channel");
        if (param != null)
            channelName = param;

        param = getParameter("timer");
        if (param != null)
            timerString = param;

        setArgs(serverName,serverPort,sourceName,channelName,timerString);      
    }

    private void setArgs(String serverName, String serverPort,
             String sourceName, String channelName, String timerString)
    {
        this.serverName = serverName;
        this.serverPort = serverPort;
        
        server = serverName + ":" + serverPort;
    
        setArgs(server,sourceName,channelName,timerString);
    }

    private void setArgs(String server, String sourceName, 
            String ChannelName, String timerString)
    {
        long timerInterval = TIMER_INTERVAL;

        try {
            timerInterval = Long.parseLong(timerString);
        }  catch (Throwable ignore){}

        setArgs(server,sourceName,channelName,timerInterval);       
    }

    private void setArgs(String server, String sourceName,
        String channelName, long timerInterval)
    {
        this.server = server;
        serverText.setText(server);
        
        this.sourceName = sourceName;
        sourceText.setText(sourceName);
        
        this.channelName = channelName;
        channelText.setText(channelName);
        
        this.timerInterval = timerInterval;
        timerText.setText(""+timerInterval);
    }

    private void setArgsFromTextFields()
    {
        setArgs (   
            serverText.getText(),
            sourceText.getText(),
            channelText.getText(),
            timerText.getText()
        );
    }
    
    private void openConnection()
    {
        if (connected) return;
        
        try {
            disableStart();
            setArgsFromTextFields();
            messagePanel.message("Attempting connection to sever...");
            source=new Source();
            source.OpenRBNBConnection(server,sourceName);
            sMap = new ChannelMap();
            int index = sMap.Add(channelName);
            connected = true;
            messagePanel.message("Connection made to sever...");
            enableStart();
            start();
            connectButton.setLabel(DISCONNECT);
            connectButton.setActionCommand(connectButton.getLabel());
        } catch (SAPIException se)
        {
            messagePanel.message("SAPIException = " + se);
        }
    }
    
    private void enableStart() {
        startStopButton.setEnabled(true);
    }

    private void disableStart() {
        startStopButton.setEnabled(false);
    }

    private void closeConnection()
    {
        if (!connected) return;
        stop();
        disableStart();
        connected = false;
        source.CloseRBNBConnection();
        connectButton.setLabel(CONNECT);
        connectButton.setActionCommand(connectButton.getLabel());
    }

    private void startThread()
    {
        
        if (!connected) return;

        if (runit) return;
        
        // Use this inner class to hide the public run method
        Runnable r = new Runnable() {
            public void run() {
              runWork();
            }
        };
        runit = true;
        timerThread = new Thread(r, "Timer");
        timerThread.start();
        messagePanel.message("Start: sever = " + server);
        messagePanel.message("   source = " + sourceName + " with " + channelName);
        messagePanel.message("   timer interval = " + timerInterval);
    }

    private void stopThread()
    {
        if (!connected) return;
        
        if (runit)
        {
            runit = false;
            timerThread.interrupt();
            messagePanel.message("Stopped thread.");
        }
    }
    
    private void runWork ()
    {
        try {
            while(connected && runit)
            {
                // Push data onto the server:
                // System.out.print("Put new data to server: ");
                sMap.PutTimeAuto("timeofday");
                double data[] = new double[1];
                data[0] = base.next();
                sMap.PutDataAsFloat64(index,data);
                messagePanel.message("" + data[0]);
                source.Flush(sMap);
                Thread.sleep(timerInterval);
            }
        } catch (SAPIException se) {
            // se.printStackTrace();
            messagePanel.message("SAPIException " + se + "; "); 
        } catch (InterruptedException e) {
            //e.printStackTrace();
            messagePanel.message("InterrupedExcetion; ");
        }
        timerThread = null;
    }
    
    private boolean isRunning()
    {
        return (connected && runit);
    }
    
    public void init() {
        setArgs();
        setLayout();
        repaint();
        messagePanel.message("initializing... ");
    }

    public void start() {
        messagePanel.message("starting... ");
        startThread();
        startStopButton.setLabel(STOP);
        startStopButton.setActionCommand(startStopButton.getLabel());
    }

    public void stop() {
        messagePanel.message("stopping... ");
        stopThread();
        startStopButton.setLabel(START);
        startStopButton.setActionCommand(startStopButton.getLabel());
    }

    public void destroy() {
        messagePanel.message("preparing for unloading...");
        closeConnection();
    }

    private static final String CONNECT = "Connect";
    private static final String DISCONNECT = "Disconnect";
    private Button connectButton = new Button(CONNECT);
    
    private static final String START = "Start";
    private static final String STOP = "Stop";
    private Button startStopButton = new Button(START);
    
    private TextField serverText =
        new TextField(SERVER_NAME + ":" + SERVER_PORT,40);
    private TextField sourceText = new TextField(SOURCE_NAME,40);
    private TextField channelText = new TextField(CHANNEL_NAME,40);
    private TextField timerText = new TextField("" + TIMER_INTERVAL,40);

    MessagePanel messagePanel = new MessagePanel();

    private void setLayout()
    {
        setLayout(new BorderLayout());      

        Panel p = new Panel();
        p.setLayout(new GridLayout(2,4));
        p.add(serverText);
        p.add(new Label("Server Host : port"));
        p.add(sourceText);
        p.add(new Label("Source Name"));
        p.add(channelText);
        p.add(new Label("Channel Name"));
        p.add(timerText);
        p.add(new Label("Timer (millisec.)"));
        add("North",p);
            
        p = new Panel();
        p.add(connectButton);
        p.add(startStopButton);     
        add("South", p);
        
        p = new Panel();
        p.add(messagePanel);
        add("Center", p);
    
        startStopButton.setEnabled(false);
        startStopButton.setActionCommand(startStopButton.getLabel());
        startStopButton.addActionListener(
            new ActionListener() {
                public void actionPerformed(ActionEvent ev) {
                    startStopAction(ev.getActionCommand());
                }
            }
        );
        
        connectButton.setActionCommand(connectButton.getLabel());
        connectButton.addActionListener(
            new ActionListener() {
                public void actionPerformed(ActionEvent ev) {
                    connectAction(ev.getActionCommand());
                }
            }
        );
    
    }
    
    private void startStopAction(String command)
    {
        if (command.equals(STOP))
            stop();
        else
            start();
    }

    private void connectAction(String command)
    {
        if (command.equals(CONNECT))
            openConnection();
        else
            closeConnection();
    }
}

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