Question

in the JSF-2 application I’m working on, I need to start a server side Timer when a user does an action.
This timer must be related to the application itself, so it must survive when the user session is closed.
To solve this problem, I thought to use java.util.Timer class instantiating the timer object in an Application scoped bean.
Could it be a good solution? Are there other better ways to achive this? Thanks

Answer 1

No ejb-container

If your container doesnt have ejb capabilities (tomcat, jetty etc..), you can go with quartz scheduler library: http://quartz-scheduler.org/

They also has some nice code samples: http://quartz-scheduler.org/documentation/quartz-2.1.x/examples/Example1

EJB 3.1

If your app-server have a EJB 3.1 (glassfish, Jboss), there is a java ee standard way of creating timers. Mainly look into the @Schedule and @Timeout annotations.

Something like this might cover your usecase (method annotated @Timeout will be invoked when timer runs out)

import javax.annotation.Resource;
import javax.ejb.Stateless;
import javax.ejb.Timeout;
import javax.ejb.Timer;
import javax.ejb.TimerConfig;
import javax.ejb.TimerService;

@Stateless
public class TimerBean {
    @Resource
    protected TimerService timerService;

    @Timeout
    public void timeoutHandler(Timer timer) {
        String name = timer.getInfo().toString();
        System.out.println("Timer name=" + name);
    }

    public void startTimer(long initialExpiration, long interval, String name){      
        TimerConfig config = new TimerConfig();
        config.setInfo(name);
        config.setPersistent(false);
        timerService.createIntervalTimer(initialExpiration, interval, config);
    }
}