running periodic task at server side for servlet JSP MVC website

Question

I have developed a web application using using servlet and JSP. I am not using any framework per se ... instead using my own home brewed MVC framework

I am using MySQL as a backend.

I want to do the following

1. cleanup some data from the data base every hour
2. generate and store statistics about data every 15 minutes in an XML file somewhere

the problem is ... currently all my code runs as a result of the request recieved from a client

how do I run periodic task(s) at the server side

one solution I have right now is to creare a thread in the controller's init function ... however I am looking for other options

Thanks you for your time

Answer 1

you can use any schedular to schedule your process like quartz, spring scheduler

http://static.springsource.org/spring/docs/2.5.x/reference/scheduling.html has a good support for these stuffs with any implementation.

Answer 2

You can use ServletContextListener to execute some initialization on webapp's startup. The standard Java API way to run periodic tasks would be a combination of Timer and TimerTask. Here's a kickoff example:

public void contextInitialized(ServletContextEvent event) {
    Timer timer = new Timer(true);
    timer.scheduleAtFixedRate(new CleanDBTask(), 0, oneHourInMillis);
    timer.scheduleAtFixedRate(new StatisticsTask(), 0, oneQuartInMillis);
}

where the both tasks can look like:

public class CleanDBTask extends TimerTask {
    public void run() {
        // Implement.
    }
}

The newer java.util.concurrent way would be a combination of ScheduledExecutorService and just a Runnable. Here's a kickoff example:

private ScheduledExecutorService scheduler;

public void contextInitialized(ServletContextEvent event) {
    scheduler = Executors.newSingleThreadScheduledExecutor();
    scheduler.scheduleAtFixedRate(new CleanDBTask(), 0, 1, TimeUnit.HOURS);
    scheduler.scheduleAtFixedRate(new StatisticsTask(), 0, 15, TimeUnit.MINUTES);
}

public void contextDestroyed(ServletContextEvent event) {
    scheduler.shutdown();
}