I wrote a program and now I am expected to convert it to a daemon. Since I am a noob and dont know anything about it, can you please tell me how can I do it or can you please give me basic tutorials or readings about it ? I really want to learn how I can do it ?
Thank you all
Java class:
package example;
import java.util.Date;
import java.util.Timer;
import java.util.TimerTask;
import org.apache.commons.daemon.*;
class EchoTask extends TimerTask {
@Override
public void run() {
System.out.println(new Date() + " running ...");
}
}
public class Main implements Daemon {
private static Timer timer = null;
public static void main(String[] args) {
timer = new Timer();
timer.schedule(new EchoTask(), 0, 1000);
}
@Override
public void init(DaemonContext dc) throws DaemonInitException, Exception {
System.out.println("initializing ...");
}
@Override
public void start() throws Exception {
System.out.println("starting ...");
main(null);
}
@Override
public void stop() throws Exception {
System.out.println("stopping ...");
if (timer != null) {
timer.cancel();
}
}
@Override
public void destroy() {
System.out.println("done.");
}
}
Shell start/stop script:
#!/bin/sh
# Setup variables
EXEC=/usr/bin/jsvc
JAVA_HOME=/usr/lib/jvm/java-6-sun
CLASS_PATH="/usr/share/java/commons-daemon.jar":"/path/to/your.jar"
CLASS=example.Main
USER=foo
PID=/tmp/example.pid
LOG_OUT=/tmp/example.out
LOG_ERR=/tmp/example.err
do_exec()
{
$EXEC -home "$JAVA_HOME" -cp $CLASS_PATH -user $USER -outfile $LOG_OUT -errfile $LOG_ERR -pidfile $PID $1 $CLASS
}
case "$1" in
start)
do_exec
;;
stop)
do_exec "-stop"
;;
restart)
if [ -f "$PID" ]; then
do_exec "-stop"
do_exec
else
echo "service not running, will do nothing"
exit 1
fi
;;
*)
echo "usage: daemon {start|stop|restart}" >&2
exit 3
;;
esac
And the effect:
$ ./service start && sleep 5 && ./service stop
$ cat /tmp/example.out
initializing ...
starting ...
Fri Oct 07 16:26:54 EEST 2011 running ...
Fri Oct 07 16:26:55 EEST 2011 running ...
Fri Oct 07 16:26:56 EEST 2011 running ...
Fri Oct 07 16:26:57 EEST 2011 running ...
Fri Oct 07 16:26:58 EEST 2011 running ...
stopping ...
done.