[jboss-dev-forums] [JBoss AS 7 Development] - Re: Access EAR classpath from MBean in JBoss Module?

Zachary Bedell do-not-reply at jboss.com
Tue Sep 25 10:12:49 EDT 2012 

Zachary Bedell [https://community.jboss.org/people/zbedell] created the discussion

"Re: Access EAR classpath from MBean in JBoss Module?"

To view the discussion, visit: https://community.jboss.org/message/761402#761402

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The location of the jboss-service.xml doesn't appear to make a difference.  Step-debugging through the MBean's start() method, it looks like the TCCL is set in such a way that I don't have a chance of getting at my deployment's resources.  Specifically:

public void start() throws Exception {
  // ...
  final ClassLoader loader = Thread.currentThread().getContextClassLoader();
  URL loginConfig = loader.getResource(...);
  // ...
}


Inspecting loader at this point gives:
  ModuleClassLoader for Module "ucs.jb4compat:main" from local module loader @23e8f4e1 (roots: /opt/software/sag/sag_dev/modules)
IE the TCCL is the module's ClassLoader, not that of the EAR deployment.  To the best of my knowledge, I don't have any EAR classes available at that point from which I could grab an appropriate ClassLoader.

Looking up the stack a bit, I see:
// org.jboss.as.service.AbstractService:
protected void invokeLifecycleMethod(final Method method) throws InvocationTargetException, IllegalAccessException {
        if (method != null) {
            final ClassLoader old = SecurityActions.setThreadContextClassLoader(mBeanInstance.getClass().getClassLoader());
            try {
                method.invoke(mBeanInstance);
            } finally {
                SecurityActions.resetThreadContextClassLoader(old);
            }
        }
    }

Which appears to stash the TCCL at that point and explicictly set it to the MBean's ClassLoader.  The stashed TCCL (old) at that point is "ModuleClassLoader for Module "org.jboss.as.sar:main" from local module loader @23e8f4e1 (roots: /opt/software/sag/sag_dev/modules)".

I've tried repackaging my resource (login-config.xml) inside the ear as ear//lib/config.sar//META-INF/login-config.xml as well as ear//lib/config.sar//login-config.xml, but none of the ClassLoader's I have available within the MBean's start() method are anything related to my EAR or its contents.

On a side note, I realize root-of EAR isn't expected to be in Classpath per EE spec, but I thought that contents of EAR/META-INF should be.  So in this case EAR/META-INF/login-config.xml would be equally accessible as EAR/lib/config.jar//META-INF/login-config.xml, assuming I had a ClassLoader with a view of the EAR.  Is that incorrect?  Granted the distinction is moot unless I can find an appropriate ClassLoader to pull from.

Just by way of structure, here's what I'm working with at the moment:

The EAR:
/Work/ExactlyWatt/java/dist/server/deployments $ unzip -l ExactlyWatt.ear 
Archive:  ExactlyWatt.ear
  Length     Date   Time    Name
 --------    ----   ----    ----
        0  09-25-12 09:33   META-INF/
      106  09-25-12 09:33   META-INF/MANIFEST.MF
        0  09-25-12 09:33   lib/
 11378038  09-25-12 09:33   ExactlyWatt.war
    55168  09-25-12 09:33   ExactlyWatt_ejb.jar
...
      866  09-25-12 09:33   lib/config.jar (See below)
...
    40161  09-25-12 09:33   lib/ydoclet-runtime.jar
      568  09-25-12 09:32   META-INF/application.xml
     1137  09-21-12 15:12   META-INF/exactlywatt-ds.xml
     1050  09-24-12 15:26   META-INF/jboss-service.xml

config.jar within EAR/lib: 
/Work/ExactlyWatt/java/dist/server/deployments/ear $ unzip -l lib/config.jar 
 Archive:  lib/config.jar
   Length     Date   Time    Name
  --------    ----   ----    ----
         0  09-25-12 09:33   META-INF/
       106  09-25-12 09:33   META-INF/MANIFEST.MF
       936  06-23-11 13:22   META-INF/login-config.xml
  --------                   -------
      1042                   3 files

EAR/META-INF/jboss-service.xml:
/Work/ExactlyWatt/java/dist/server/deployments/ear $ cat META-INF/jboss-service.xml 
<?xml version="1.0" encoding="UTF-8"?>
<server xmlns="urn:jboss:service:7.0"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="urn:jboss:service:7.0 http://ucmsload.courtnet.org/dtds/jb7/jboss-service_7_0.xsd">
*  <!-- Note this MBean deploys & works properly.  It's accessing files on-disk in standalone/configuration rather than trying to pull from classloader.  -->*

  <mbean code="ucs.jb4compat.SystemPropertiesService" name="jboss.util:type=Service,name=SystemProperties-ExactlyWatt">
    <attribute name="URLList">configuration/exactlywatt.properties</attribute>
  </mbean>

  <mbean code="ucs.jb4compat.DynamicLoginConfig" name="sample-app:service=DynamicLoginConfig,domain=ExactlyWatt">
*    <!-- With or without "META-INF/" here makes no difference. -->*
    <attribute name="AuthConfig">*META-INF/*login-config.xml</attribute>
    <depends>jboss.util:type=Service,name=SystemProperties-ExactlyWatt</depends>
  </mbean>
</server>


/Work/ExactlyWatt/java/dist/server/deployments/ear $ cat META-INF/application.xml 
<?xml version="1.0" encoding="UTF-8"?>
<application xmlns="http://java.sun.com/xml/ns/javaee" 
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
  xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://ucmsload.courtnet.org/dtds/javaee/application_6.xsd" 
  version="6">
  <description>ExactlyWatt Jar Index</description>
  <display-name>ExactlyWatt</display-name>
  <module><ejb>ExactlyWatt_ejb.jar</ejb></module>
  <module>
      <web>
         <web-uri>ExactlyWatt.war</web-uri>
         <context-root>/ExactlyWatt</context-root>
       </web>
  </module>
</application>

Note this particular attempt has jboss-service.xml directly in EAR//META-INF without a SAR file to wrap it.  If I change things to put jboss-service.xml inside EAR//config.sar//META-INF and add EAR//META-INF/jboss-app.xml with a <module><service>config.sar</service></module> and application.xml with <module><java>config.sar</java></module>, it makes no difference on any of this.  I still get the module's ClassLoader for TCCL in the MBean's start() method and have no access to the EAR deployment's contents.
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