Live demo

This LIVE demonstration of many JRobin capabilities was provided by Cherry Network Monitoring project. It uses JRobin as a RRD data backend and graphing tool.

The demo monitors various aspects of system utilization (CPU load, FTP and Apache statistics, traffic graphs, number of emails in the message queue etc) by creating real-time JRobin graphs.

Demo opens in a separate window.

The second demo (an applet) illustrates how to use JRobin to store RRD data in memory (unsigned applets are not allowed to perform any kind of disk I/O activity). The source code is basically just a translation of Tobi's minmax.pl script (you can find it in the examples subdirectory of RRDTool distribution).

Applet's source code (not something I'm too proud of ;) is given bellow:

package org.jrobin.demo;

import org.jrobin.core.*;
import org.jrobin.graph.RrdGraphDef;
import org.jrobin.graph.RrdGraph;

import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionListener;

import java.awt.event.ActionEvent;

public class AppletDemo extends JApplet {
    public static final String RRD_PATH = "random";

    static {
        try {
            RrdDb.setDefaultFactory("MEMORY");
        }
        catch (Exception e) {
            e.printStackTrace();
        }
    }

    private RrdGraphDef rrdGraphDef;
    private RrdDef rrdDef;
    private long startTime = Util.getTime();

    private UpdaterThread updater;

    public void init() {
        // UI
        JPanel contentPane = (JPanel) getContentPane();
        contentPane.add(new GraphPanel(), BorderLayout.CENTER);
        JButton restartButton = new JButton("Restart");
        restartButton.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                restart();
            }
        });
        contentPane.add(restartButton, BorderLayout.SOUTH);
        // RRD
        try {
            rrdDef = new RrdDef(RRD_PATH, startTime - 1, 300);
            rrdDef.addDatasource("a", "GAUGE", 600, Double.NaN, Double.NaN);
            rrdDef.addArchive("AVERAGE", 0.5, 1, 300);
            rrdDef.addArchive("MIN", 0.5, 12, 300);
            rrdDef.addArchive("MAX", 0.5, 12, 300);
            rrdGraphDef = new RrdGraphDef(startTime, startTime + 86400);
            rrdGraphDef.setTitle("JRobin MIN/MAX demo");
            rrdGraphDef.setLowerLimit(0);
            rrdGraphDef.datasource("a", RRD_PATH, "a", "AVERAGE");
            rrdGraphDef.datasource("b", RRD_PATH, "a", "MIN");
            rrdGraphDef.datasource("c", RRD_PATH, "a", "MAX");
            rrdGraphDef.area("a", new Color(0, 0xb6, 0xe4), "real");
            rrdGraphDef.line("b", new Color(0, 0x22, 0xe9), "min", 2);
            rrdGraphDef.line("c", new Color(0, 0xee, 0x22), "max", 2);
        }
        catch (Exception e) {
            e.printStackTrace();
        }
    }

    private void restart() {
        updater.terminate();
        start();
    }

    public void start() {
        updater = new UpdaterThread();
        updater.start();
    }

    public void stop() {
        updater.terminate();
    }

    class GraphPanel extends JPanel {
        protected void paintComponent(Graphics g) {
            try {
                RrdGraph graph = new RrdGraph(rrdGraphDef);
                graph.specifyImageSize(true);
                graph.renderImage((Graphics2D) g, getWidth(), getHeight());
            }
            catch (Exception e) {
                e.printStackTrace();
            }
        }
    }

    class UpdaterThread extends Thread {
        public static final int DELAY = 100;
        public static final int STEPS_PER_REPAINT = 5;

        private boolean shouldStop = false;
        private RrdDb rrdDb;

        public UpdaterThread() {
            try {
                this.rrdDb = new RrdDb(rrdDef);
            }
            catch (Exception e) {
                e.printStackTrace();
            }
        }

        public void run() {
            try {
                int steps = 0;
                for(long t = startTime; t < startTime + 300 * 300 && !shouldStop; 
                    t += 300) {
                    double value = Math.sin(t / 3000.0) * 50.0 + 50.0;
                    rrdDb.createSample().setTime(t).setValue(0, value).update();
                    if(steps++ % STEPS_PER_REPAINT == 0) {
                        repaint();
                    }
                    Thread.sleep(DELAY);
                }
                repaint();
            }
            catch (Exception e) {
                e.printStackTrace();
            }
        }

        void terminate() {
            shouldStop = true;
            while(isAlive()) {
                try {
                    Thread.sleep(DELAY);
                }
                catch (Exception e) {
                    e.printStackTrace();
                }
            }
        }
    }
}

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