Looking at the code this seems to get thrown from the 
attrib.getValue();
It's unclear why you'd get null as the argument but this certainly leans torward the attribute being unknown to the bean.


John Mazzitelli wrote: 
            EmsBean bean = connection.getBean(AE_WEBMODULE_BEAN);
            String aePath = bean.getAttribute("path").getValue().toString();

Which line throws that exception?  You should temporarily break this up so you can get a good indication of where that error comes from:

            EmsBean bean = connection.getBean(AE_WEBMODULE_BEAN);
            Attribute attrib = bean.getAttribute("path")
            Object value = attrib.getValue();
            String aePath = value.toString();

I'll assume bean is coming back non-null (other wise, the next line would throw an NPE).

If the getAttribute() is the one throwing it, I'll assume your MBean does not have a "getPath()" method on it.

Just a guess but that's what I would look at... see what attributes the AE_WEBMODULE_MBEAN has on it and make sure it has a readable "getPath" no-arg attribute method on it.

----- Original Message -----
From: "Bruno Wassermann" <bruno.wassermann@googlemail.com>
To: "jopr-dev" <jopr-dev@lists.jboss.org>
Sent: Thursday, August 6, 2009 1:39:28 PM GMT -05:00 US/Canada Eastern
Subject: [jopr-dev] EmsException?


Hi again, 

I have come across some weird(seeming) problem. In my ActiveBPEL discovery component, I connect to the JMX server on my Tomcat instance to look up the existence of a bean and extract a value from it, like so: 

private final static String AE_WEBMODULE_BEAN = "Catalina:j2eeType=WebModule,name=//localhost/active-bpel,J2EEApplication=none,J2EEServer=none"; 
.... 

EmsConnection connection = null; 

try { 
connection = context.getParentResourceComponent().getEmsConnection(); 
EmsBean testBean = connection.getBean("Catalina:type=Server"); 
String testPort = testBean.getAttribute("port").getValue().toString(); 
log.debug(LOG_PREFIX + "THE PORT BEAN: " + testPort); 

log.debug(LOG_PREFIX + "CONNECTION URL: " + connection.getConnectionProvider().getConnectionSettings().getServerUrl()); 

EmsBean bean = connection.getBean(AE_WEBMODULE_BEAN); 
String aePath = bean.getAttribute("path").getValue().toString(); 

The poor agent ends up complaining as follows: EmsException: Could not load attribute value null. 
Now, the same code works for retrieving a very similar MBean for Axis, the ActiveBPEL MBean name I'm using seems to be okay, testPort above is as expected. Why would it not be able to get the bean and its attributes? 

Has anyone come across this in a similar context? I have read something about a Jopr/RHQ bug that results in the same exception... 

Thanks, 

-- Bruno 


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