@Startup help...

[bsmithjj]

Hello,

I am trying to do the following:

On startup of my application, create an EJB Timer (javax.ejb.Timer) using the EJB TimerService (javax.ejb.TimerService).

The timer bean that I am trying to install is a stateless session bean.

I initially tried to use @PostConstruct on a method that would use the TimerService (@Resource private TimerService timerService) to create my timer. This didn't work immediately, so I figured, no instances of my stateless session bean have been created - fine, I turned to @Startup to create bootstrap component that gets a handle to the stateless session bean and invokes its starter method. Now I'm not sure what dependencies I need to add to the @Startup(depends={...}) list.

I know that I need the following resources available before my @Startup component's @Create method is called:

- my stateless session bean needs to be deployed
- the persistence context for my EJB jar needs to be available for injection

I've noticed that the @In annotation doesn't seem to work for my @Startup component (i.e. I can't get a reference to my stateless session bean); so I looked up the reference manually:

 MyBean myBean = null;
 try {
 myBean = (MyBean)Naming.getInitialContext().lookup("my-ear/MyBean/local");
 mailReader.startReading();
 } catch (NamingException e) {
 log.error(e,e);
 }

I can get a reference but invariably some other dependency fails (a @Factory component, etc...).

Is there someway of telling @Startup something to the effect of:

"start me up after everything else" ?

Is there a better way of installing a timer in Seam?

Thanks,
Brad Smith

[gavin.king]

The @Startup annotation has a list of dependencies, ie. names of other component which must be started first.

[bsmithjj]

Code:

@Name("mailReaderStarter")
@Scope(ScopeType.APPLICATION) // required for the @Startup to work
@Startup(depends={"mailReader"})
@Install(
 dependencies = {"mailReader"}
)
public class MailReaderStarter {

 @Logger
 private Log log;

 @In(create=true)
 private MailReader mailReader; // a Stateless session bean...

 @Create
 public void startup() {
 log.info("startup()");
 mailReader.startReading();
 }

}

Log:

13:28:30,173 INFO [Component] Component: mailReader, scope: STATELESS, type: STATELESS_SESSION_BEAN, class: com.evergreen.accesscontrol.impl.MailReaderBean, JNDI: access-control-1.0/MailReaderBean/lo
cal
...
13:28:30,220 INFO [Component] Component: mailReaderStarter, scope: APPLICATION, type: JAVA_BEAN, class: com.evergreen.accesscontrol.mail.MailReaderStarter
...
13:28:37,955 ERROR [[/access]] Exception sending context initialized event to listener instance of class org.jboss.seam.servlet.SeamListener
java.lang.UnsupportedOperationException: Stateless psuedo-scope does not have a Context object
 at org.jboss.seam.ScopeType.getContext(ScopeType.java:95)
 at org.jboss.seam.contexts.Lifecycle.startup(Lifecycle.java:150)
 at org.jboss.seam.contexts.Lifecycle.startup(Lifecycle.java:145)
 at org.jboss.seam.contexts.Lifecycle.endInitialization(Lifecycle.java:126)
 at org.jboss.seam.init.Initialization.init(Initialization.java:430)
 at org.jboss.seam.servlet.SeamListener.contextInitialized(SeamListener.java:33)
 at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:3729)
 at org.apache.catalina.core.StandardContext.start(StandardContext.java:4187)
 at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:759)
 at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:739)
 at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:524)
 at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
 at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
 at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
 at java.lang.reflect.Method.invoke(Method.java:585)
 at org.apache.commons.modeler.BaseModelMBean.invoke(BaseModelMBean.java:503)
 at org.jboss.mx.server.RawDynamicInvoker.invoke(RawDynamicInvoker.java:164)
 at org.jboss.mx.server.MBeanServerImpl.invoke(MBeanServerImpl.java:659)
 at org.apache.catalina.core.StandardContext.init(StandardContext.java:5116)
 at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
 at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
 at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
 at java.lang.reflect.Method.invoke(Method.java:585)
 at org.apache.commons.modeler.BaseModelMBean.invoke(BaseModelMBean.java:503)
 at org.jboss.mx.server.RawDynamicInvoker.invoke(RawDynamicInvoker.java:164)
 at org.jboss.mx.server.MBeanServerImpl.invoke(MBeanServerImpl.java:659)
 at org.jboss.web.tomcat.tc5.TomcatDeployer.performDeployInternal(TomcatDeployer.java:297)
 at org.jboss.web.tomcat.tc5.TomcatDeployer.performDeploy(TomcatDeployer.java:103)
 at org.jboss.web.AbstractWebDeployer.start(AbstractWebDeployer.java:371)
 at org.jboss.web.WebModule.startModule(WebModule.java:83)
 at org.jboss.web.WebModule.startService(WebModule.java:61)
 at org.jboss.system.ServiceMBeanSupport.jbossInternalStart(ServiceMBeanSupport.java:289)
 at org.jboss.system.ServiceMBeanSupport.jbossInternalLifecycle(ServiceMBeanSupport.java:245)
 at sun.reflect.GeneratedMethodAccessor3.invoke(Unknown Source)
 at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
 at java.lang.reflect.Method.invoke(Method.java:585)
 at org.jboss.mx.interceptor.ReflectedDispatcher.invoke(ReflectedDispatcher.java:155)
 at org.jboss.mx.server.Invocation.dispatch(Invocation.java:94)
 at org.jboss.mx.server.Invocation.invoke(Invocation.java:86)
 at org.jboss.mx.server.AbstractMBeanInvoker.invoke(AbstractMBeanInvoker.java:264)
 at org.jboss.mx.server.MBeanServerImpl.invoke(MBeanServerImpl.java:659)
 at org.jboss.system.ServiceController$ServiceProxy.invoke(ServiceController.java:978)
 at $Proxy0.start(Unknown Source)
 at org.jboss.system.ServiceController.start(ServiceController.java:417)
 at sun.reflect.GeneratedMethodAccessor6.invoke(Unknown Source)
 at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
 at java.lang.reflect.Method.invoke(Method.java:585)
 at org.jboss.mx.interceptor.ReflectedDispatcher.invoke(ReflectedDispatcher.java:155)
 at org.jboss.mx.server.Invocation.dispatch(Invocation.java:94)
 at org.jboss.mx.server.Invocation.invoke(Invocation.java:86)
 at org.jboss.mx.server.AbstractMBeanInvoker.invoke(AbstractMBeanInvoker.java:264)
 at org.jboss.mx.server.MBeanServerImpl.invoke(MBeanServerImpl.java:659)
 at org.jboss.mx.util.MBeanProxyExt.invoke(MBeanProxyExt.java:210)
 at $Proxy44.start(Unknown Source)
 at org.jboss.web.AbstractWebContainer.start(AbstractWebContainer.java:466)
 at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
 at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
 at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
 at java.lang.reflect.Method.invoke(Method.java:585)
 at org.jboss.mx.interceptor.ReflectedDispatcher.invoke(ReflectedDispatcher.java:155)
 at org.jboss.mx.server.Invocation.dispatch(Invocation.java:94)
 at org.jboss.mx.interceptor.AbstractInterceptor.invoke(AbstractInterceptor.java:133)
 at org.jboss.mx.server.Invocation.invoke(Invocation.java:88)
 at org.jboss.mx.interceptor.ModelMBeanOperationInterceptor.invoke(ModelMBeanOperationInterceptor.java:142)
 at org.jboss.mx.interceptor.DynamicInterceptor.invoke(DynamicInterceptor.java:97)
 at org.jboss.system.InterceptorServiceMBeanSupport.invokeNext(InterceptorServiceMBeanSupport.java:238)
 at org.jboss.ws.server.WebServiceDeployer.start(WebServiceDeployer.java:117)
 at org.jboss.deployment.SubDeployerInterceptorSupport$XMBeanInterceptor.start(SubDeployerInterceptorSupport.java:188)
 at org.jboss.deployment.SubDeployerInterceptor.invoke(SubDeployerInterceptor.java:95)
 at org.jboss.mx.server.Invocation.invoke(Invocation.java:88)
 at org.jboss.mx.server.AbstractMBeanInvoker.invoke(AbstractMBeanInvoker.java:264)
 at org.jboss.mx.server.MBeanServerImpl.invoke(MBeanServerImpl.java:659)
 at org.jboss.mx.util.MBeanProxyExt.invoke(MBeanProxyExt.java:210)
 at $Proxy45.start(Unknown Source)
 at org.jboss.deployment.MainDeployer.start(MainDeployer.java:1007)
 at org.jboss.deployment.MainDeployer.start(MainDeployer.java:997)
 at org.jboss.deployment.MainDeployer.deploy(MainDeployer.java:808)
 at org.jboss.deployment.MainDeployer.deploy(MainDeployer.java:771)
 at sun.reflect.GeneratedMethodAccessor13.invoke(Unknown Source)
 at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
 at java.lang.reflect.Method.invoke(Method.java:585)
 at org.jboss.mx.interceptor.ReflectedDispatcher.invoke(ReflectedDispatcher.java:155)
 at org.jboss.mx.server.Invocation.dispatch(Invocation.java:94)
 at org.jboss.mx.interceptor.AbstractInterceptor.invoke(AbstractInterceptor.java:133)
 at org.jboss.mx.server.Invocation.invoke(Invocation.java:88)
 at org.jboss.mx.interceptor.ModelMBeanOperationInterceptor.invoke(ModelMBeanOperationInterceptor.java:142)
 at org.jboss.mx.server.Invocation.invoke(Invocation.java:88)
 at org.jboss.mx.server.AbstractMBeanInvoker.invoke(AbstractMBeanInvoker.java:264)
 at org.jboss.mx.server.MBeanServerImpl.invoke(MBeanServerImpl.java:659)
 at org.jboss.mx.util.MBeanProxyExt.invoke(MBeanProxyExt.java:210)
 at $Proxy6.deploy(Unknown Source)
 at org.jboss.deployment.scanner.URLDeploymentScanner.deploy(URLDeploymentScanner.java:421)
 at org.jboss.deployment.scanner.URLDeploymentScanner.scan(URLDeploymentScanner.java:610)
 at org.jboss.deployment.scanner.AbstractDeploymentScanner$ScannerThread.doScan(AbstractDeploymentScanner.java:263)
 at org.jboss.deployment.scanner.AbstractDeploymentScanner$ScannerThread.loop(AbstractDeploymentScanner.java:274)
 at org.jboss.deployment.scanner.AbstractDeploymentScanner$ScannerThread.run(AbstractDeploymentScanner.java:225)

help?

[gavin.king]

So you have designated a *stateless* bean as a @Startup object?! This doesn't really make sense. Only stateful objects can be meaningfully "created".

[bsmithjj]

Huh?

I designated an APPLICATION scoped bean as the startup object - I have the startup object get a handle to a stateless bean and invoke a method which subsequently creates timer object.

Going back to the start of this thread...I am trying to start an EJB Timer on startup of the application - it doesn't seem like an unreasonable thing to do - it's pretty darn simple to start a timer using Spring (via JDK Timers or Quartz) or a good-ole-fashioned ServletContextListener, etc. I hoped that Seam would be helpful in this regards since I am already using Seam in this application.

So given that "This doesn't really make sense. ", do you have any suggestions for starting a Timer process on startup in an EJB3 / Seam application?

As an alternative, I can simply put a link or button on page that invokes the method which creates the timer - this works fine - I've tested it. But really I would like to be able to achieve the 'startup behavior'.

Thanks,
Brad Smith

PS: It's interesting you say that:

Only stateful objects can be meaningfully "created".

because in this thread http://www.jboss.com/index.html?module=bb&op=viewtopic&t=98545&postdays=0&postorder=asc&start=0
everybody seems to insist that a stateless bean must be 'created' - how confusing!?!

[pmuir]

If you can use JavaBeans rather than EJB3 this will work (with Seam from CVS since Gavin fixed http://jira.jboss.com/jira/browse/JBSEAM-679)

@Startup(depends="manager")
@Scope(ScopeType.APPLICATION)
public class Controller {

 @In(create=true)
 private Manager manager;

 @Create
 public void create() throws Exception {
 // Schedule
 manager.schedule(...);
 }

}

@Name("manager")
@Scope(ScopeType.EVENT)
public class Manager {

 @Transactional
 @Asynchronous
 public void schedule(...) {
 ...
 }
}

[bsmithjj]

this is a helpful suggestion - thanks.

Unfortunately - I'll probably going live with Seam 1.1.0 so I am reluctant to work with a nightly build right now.

I still would like to hear any suggestions for building EJB Timer solutions in a Seam-EJB3 app - with ideas for kickstarting the timers on startup of the application.


Thanks,
Brad Smith

[gavin.king]

"bsmithjj" wrote:
Huh?

I designated an APPLICATION scoped bean as the startup object - I have the startup object get a handle to a stateless bean and invoke a method which subsequently creates timer object.

You have:

@Startup(depends={"mailReader"})

This tells seam to "start" the mailReader component before starting the "mailReaderStarter" component. But its not meaningful to "start" a stateless component. If you remove the depends, your code will probably work as written.

"bsmithjj" wrote:
Going back to the start of this thread...I am trying to start an EJB Timer on startup of the application - it doesn't seem like an unreasonable thing to do - it's pretty darn simple to start a timer using Spring (via JDK Timers or Quartz) or a good-ole-fashioned ServletContextListener, etc. I hoped that Seam would be helpful in this regards since I am already using Seam in this application.

Slow down, I have a lot of posts to answer every day. I thought I had given you enough of a hint, but apparently not.

PS: It's interesting you say that:

Only stateful objects can be meaningfully "created".

because in this thread http://www.jboss.com/index.html?module=bb&op=viewtopic&t=98545&postdays=0&postorder=asc&start=0
everybody seems to insist that a stateless bean must be 'created' - how confusing!?!

This is an artefact of representing something that is conceptually stateless in an object-oriented language where components have state and lifecycle.

What I shoudl have typed is: Only stateful objects can be meaningfully "started".