Question

我正在尝试在JBoss6.4上部署HASingleton。我按照this教程提出了以下建议：

我通过JNDI注入计时器bean来创建一个应该启动计时器（自己的计时器接口）的服务。

public class HATimerService implements Service<String> {
    private Logger logger = Logger.getLogger(HATimerService.class);

    private final AtomicBoolean started = new AtomicBoolean(false);
    private ServiceName serviceName;
    private final InjectedValue<ServerEnvironment> env = new InjectedValue();

    private String JNDI = "java:global/my-ear/my-module/MyTimer"

    public HATimerService() {
        serviceName = ServiceName.JBOSS.append(new String[]{"my", "ha", "singleton", "MyHaService"});
    }

    public String getValue() throws IllegalStateException, IllegalArgumentException {
        return "";
    }

    public void start(StartContext context) throws StartException {
        if(!started.compareAndSet(false, true)) {
            throw new StartException("The service is still started!");
        } else {
            try {
                InitialContext e = new InitialContext();
                TimerScheduler myTimer = (TimerScheduler)e.lookup(JNDI);
                timer.startTimer();

            } catch (NamingException var6) {
                throw new StartException("Could not initialize timer", var6);
            }
        }
    }

    public void stop(StopContext context) {
        if(started.compareAndSet(true, false)) {
            try {
                InitialContext e = new InitialContext();
                ((TimerScheduler)e.lookup(JNDI)).stopTimer();
            } catch (NamingException var4) {
                logger.error("Could not stop timer", var4);
            }
        }

    }

    public ServiceName getServiceName() {
        return serviceName;
    }

    public InjectedValue<ServerEnvironment> getEnvironment() {
        return env;
    }
}

我还有一个激活服务的激活器。

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

    public HATimerServiceActivator() {
    }

    public void activate(ServiceActivatorContext context) {
            HATimerService service = new HATimerService();
            this.log.info(service.getServiceName() + "HATimerService will be installed");

            SingletonService singleton = new SingletonService(service, service.getServiceName());
            singleton.build(new DelegatingServiceContainer(context.getServiceTarget(), context.getServiceRegistry()))
                     .addDependency(ServerEnvironmentService.SERVICE_NAME, ServerEnvironment.class, service.getEnvironment())
                     .setInitialMode(Mode.ACTIVE)
                     .install();
    }
}

计时器bean，HATimerService和HATimerServiceActivator都部署在名为my-ear的耳中。在日志文件中我可以看到：

JNDI bindings for session bean named MyTimer.... :
java:global/my-ear/my-module/MyTimer

但是，每隔一段时间（约占所有部署的1/3），由于NameNotFoundException JNDI查找失败，此设置失败。完整的例外情况是：Caused by: javax.naming.NameNotFoundException: Error looking up my-ear/my-module/MyTimer, service service jboss.naming.context.java.global.my-ear.my-module.MyTimer is not started

我的猜测是，这可能是某种竞争条件，其中bean尚未在JNDI树中注册。如何让服务等待查找，直到bean可用？

Answer 1

似乎有可能在部署单元上创建依赖关系。创建SingletonService时，可以添加以下依赖项：

ServiceName ejbDependency = ServiceName.of("jboss", "deployment", "subunit", "my-ear.ear", "my-module.jar", "component", "MyTimerBean", "START");
singleton.build(new DelegatingServiceContainer(context.getServiceTarget(), context.getServiceRegistry()))
                 .addDependency(ServerEnvironmentService.SERVICE_NAME, ServerEnvironment.class, service.getEnvironment())
                 .setInitialMode(Mode.ACTIVE)
                 .addDependency(ejbDependency)
                 .install();

只要ejbDependency是正确的依赖关系，就会在bean启动后执行查找。

HASingleton无法查找JNDI bean

1 个答案: