第6章 Web アプリケーションのクラスター化

サービスクラスコード例

public class HATimerService implements Service<String> {
    private static final Logger LOGGER = Logger.getLogger(HATimerService.class.toString());
    public static final ServiceName SINGLETON_SERVICE_NAME = ServiceName.JBOSS.append("quickstart", "ha", "singleton", "timer");

    /**
     * A flag whether the service is started.
     */
    private final AtomicBoolean started = new AtomicBoolean(false);

    /**
     * @return the name of the server node
     */
    public String getValue() throws IllegalStateException, IllegalArgumentException {
        LOGGER.info(String.format("%s is %s at %s", HATimerService.class.getSimpleName(), (started.get() ? "started" : "not started"), System.getProperty("jboss.node.name")));
        return System.getProperty("jboss.node.name");
    }

    public void start(StartContext arg0) throws StartException {
        if (!started.compareAndSet(false, true)) {
            throw new StartException("The service is still started!");
        }
        LOGGER.info("Start HASingleton timer service '" + this.getClass().getName() + "'");

        final String node = System.getProperty("jboss.node.name");
        try {
            InitialContext ic = new InitialContext();
            ((Scheduler) ic.lookup("global/jboss-cluster-ha-singleton-service/SchedulerBean!org.jboss.as.quickstarts.cluster.hasingleton.service.ejb.Scheduler"))
                .initialize("HASingleton timer @" + node + " " + new Date());
        } catch (NamingException e) {
            throw new StartException("Could not initialize timer", e);
        }
    }

    public void stop(StopContext arg0) {
        if (!started.compareAndSet(true, false)) {
            LOGGER.warning("The service '" + this.getClass().getName() + "' is not active!");
        } else {
            LOGGER.info("Stop HASingleton timer service '" + this.getClass().getName() + "'");
            try {
                InitialContext ic = new InitialContext();
                ((Scheduler) ic.lookup("global/jboss-cluster-ha-singleton-service/SchedulerBean!org.jboss.as.quickstarts.cluster.hasingleton.service.ejb.Scheduler")).stop();
            } catch (NamingException e) {
                LOGGER.info("Could not stop timer:" + e.getMessage());
            }
        }
    }
}

サービスアクティベーターコード例

public class HATimerServiceActivator implements ServiceActivator {
    private final Logger log = Logger.getLogger(this.getClass().toString());

    @Override
    public void activate(ServiceActivatorContext context) {
        log.info("HATimerService will be installed!");

        HATimerService service = new HATimerService();
        ServiceName factoryServiceName = SingletonServiceName.BUILDER.getServiceName("server", "default");
        ServiceController<?> factoryService = context.getServiceRegistry().getRequiredService(factoryServiceName);
        SingletonServiceBuilderFactory factory = (SingletonServiceBuilderFactory) factoryService.getValue();
        ServiceName ejbComponentService = ServiceName.of("jboss", "deployment", "unit", "jboss-cluster-ha-singleton-service.jar", "component", "SchedulerBean", "START");
        factory.createSingletonServiceBuilder(HATimerService.SINGLETON_SERVICE_NAME, service)
            .electionPolicy(new PreferredSingletonElectionPolicy(new SimpleSingletonElectionPolicy(), new NamePreference("node1/singleton")))
            .build(new DelegatingServiceContainer(context.getServiceTarget(), context.getServiceRegistry()))
            .setInitialMode(ServiceController.Mode.ACTIVE)
            .addDependency(ejbComponentService)
            .install();
    }
}

META-INF/services/org.jboss.msc.service.ServiceActivator ファイル例

org.jboss.as.quickstarts.cluster.hasingleton.service.ejb.HATimerServiceActivator

スケジューラーインターフェースコード例

public interface Scheduler {

    void initialize(String info);

    void stop();

}

シングルトン Bean コード例

@Singleton
public class SchedulerBean implements Scheduler {
    private static Logger LOGGER = Logger.getLogger(SchedulerBean.class.toString());
    @Resource
    private TimerService timerService;

    @Timeout
    public void scheduler(Timer timer) {
        LOGGER.info("HASingletonTimer: Info=" + timer.getInfo());
    }

    @Override
    public void initialize(String info) {
        ScheduleExpression sexpr = new ScheduleExpression();
        // set schedule to every 10 seconds for demonstration
        sexpr.hour("*").minute("*").second("0/10");
        // persistent must be false because the timer is started by the HASingleton service
        timerService.createCalendarTimer(sexpr, new TimerConfig(info, false));
    }

    @Override
    public void stop() {
        LOGGER.info("Stop all existing HASingleton timers");
        for (Timer timer : timerService.getTimers()) {
            LOGGER.fine("Stop HASingleton timer: " + timer.getInfo());
            timer.cancel();
        }
    }
}