Bugs item #854907, was opened at 2003-12-05 19:35
Message generated for change (Settings changed) made by juhalindfors
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Category: JBossMX
Group: v3.2
>Status: Closed
>Resolution: Fixed
Priority: 5
Submitted By: Brian Madigan (bmadigan2003)
>Assigned to: Nobody/Anonymous (nobody)
Summary: NullPointerException in ModelMBeanInvoker at startup
Initial Comment:
I have defined an XMBean following the JBoss admin and
developer guide examples (starting at Page 119)
The XMBean descriptor validates ok against it's DTD,
and I don't find any discrepancies between the
descriptor and the implementing class.
During initialization, the XMBean fails to start,
throwing a NullPointerException during registration
Relevant portion of the stack trace is below:
[java] Caused by: java.lang.NullPointerException
[java] at
org.jboss.mx.modelmbean.ModelMBeanInvoker.preRegister(ModelMBeanInvoker.java:243)
[java] at
javax.management.modelmbean.RequiredModelMBean.preRegister(RequiredModelMBean.java:218)
[java] at
org.jboss.mx.modelmbean.ModelMBeanInvoker.preRegister(ModelMBeanInvoker.java:284)
[java] at
org.jboss.mx.server.registry.BasicMBeanRegistry.registerMBean(BasicMBeanRegistry.java:148)
[java] at
sun.reflect.GeneratedMethodAccessor2.invoke(Unknown Source)
[java] at
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
[java] at java.lang.reflect.Method.invoke(Method.java:324)
[java] at
org.jboss.mx.capability.ReflectedMBeanDispatcher.invoke(ReflectedMBeanDispatcher.java:284)
[java] at
org.jboss.mx.interceptor.ObjectReferenceInterceptor.invoke(ObjectReferenceInterceptor.java:59)
[java] at
org.jboss.mx.interceptor.MBeanAttributeInterceptor.invoke(MBeanAttributeInterceptor.java:43)
[java] at
org.jboss.mx.interceptor.PersistenceInterceptor2.invoke(PersistenceInterceptor2.java:93)
[java] at
org.jboss.mx.server.MBeanInvoker.invoke(MBeanInvoker.java:75)
[java] at
javax.management.modelmbean.RequiredModelMBean.invoke(RequiredModelMBean.java:141)
[java] at
org.jboss.mx.server.MBeanServerImpl.invoke(MBeanServerImpl.java:549)
[java] at
org.jboss.mx.server.MBeanServerImpl.registerMBean(MBeanServerImpl.java:994)
[java] at
org.jboss.mx.server.MBeanServerImpl.registerMBean(MBeanServerImpl.java:954)
[java] at
org.jboss.mx.server.MBeanServerImpl.createMBean(MBeanServerImpl.java:322)
[java] at
org.jboss.system.ServiceCreator.install(ServiceCreator.java:114)
[java] at
org.jboss.system.ServiceConfigurator.internalInstall(ServiceConfigurator.java:155)
[java] at
org.jboss.system.ServiceConfigurator.install(ServiceConfigurator.java:118)
Poking around in the source code (3.2.1), the only two
lines in preRegister( ) that are likely to be causing a
nullPointerException are these:
Descriptor mbeanDescriptor =
infoSupport.getMBeanDescriptor();
mbeanDescriptor.setField(.......
....
xmbean descriptor is attached.
----------------------------------------------------------------------
Comment By: Juha Lindfors (juhalindfors)
Date: 2003-12-06 01:20
Message:
Logged In: YES
user_id=175239
Why are you extending RequiredModelMBean ?
If you do that you need to ensure that ModelMBeanInfo is set
before registering the MBean. But you're invoking the
no-args constructor from superclass that won't set the metadata.
The programming idiom to use model MBeans is to create an
instance of the MMB and then configure it with a reference
to your POJO and the metadata that describes your interface:
ModelMBean mmb = new RequiredModelMBean();
mmb.setModelMBeanInfo(mymetadata);
mmb.setManagedResource("ObjectReference", mypojo);
server.registerMBean(objectName, mmb);
Or for XMBean:
ModelMBean mmb = new XMBean("http://url.to.my.descriptor";);
server.registerMBean(objectName, mmb);
I'll see if there's a reasonable default failure exception
that should be thrown when you use MMB incorrectly.
----------------------------------------------------------------------
Comment By: Brian Madigan (bmadigan2003)
Date: 2003-12-05 19:41
Message:
Logged In: YES
user_id=774779
Attached MBean impl. just in case.
----------------------------------------------------------------------
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