Deploy and managing a custom Java administrative client program with multiple J2EE appservers

 

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The WAS completely implements the J2EE Management specification, also known as JSR-77. However, some differences in details between the J2EE specification and the WAS implementation are important for you to understand when you develop a Java administrative client program to manage multiple vendor servers. For information, see...

 

Overview

When your administrative client program accesses WAS exclusively, you can use the Java APIs and WAS-defined MBeans to manage them. If your program needs to access both WAS and other J2EE servers, use the API defined in the J2EE Management specification.

 

Procedure

  1. Connect to a J2EE server. Connect to a server by looking up the Management enterprise bean from the JNDI. The Management enterprise bean supplies a remote interface to the MBean server that runs in the appserver. The Management enterprise bean works almost exactly like the WAS administrative client, except that it does not provide WAS specific functionality. The following example shows how to look up the Management enterprise bean.

    import javax.management.j2ee.ManagementHome; import javax.management.j2ee.Management;
    
    Properties props = new Properties();
     props.setProperty(Context.PROVIDER_URL, "iiop://myhost:2809");
    Context ic = new InitialContext(props);
    Object obj = ic.lookup("ejb/mgmt/MEJB");
    ManagementHome mejbHome = (ManagementHome)
            PortableRemoteObject.narrow(obj, ManagementHome.class);
    Management mejb = mejbHome.create();
    
    
    The example gets an initial context to an appserver by passing the host and port of the RMI connector. You must explicitly code the RMI port, in this case 2809. The lookup method looks up the ejb/mgmt/MEJB path, which is the location of the Management enterprise bean home. The example then creates the mejb stateless session bean, which you use in the next step.

  2. Manage multiple vendor appservers.

    After creating the mejb stateless session bean, you can use it to manage your appservers. Components from the appservers appear as MBeans, which the specification defines. These MBeans all have the j2eeType key property. This key property is one of a set of types that the specification defines. All of these types have a set of exposed attributes.

    Use the following example to guide you in managing multiple vendor appservers. The example uses the JVM MBean to determine what the current heap size is for the appserver.

    ObjectName jvmQuery = new ObjectName("*:j2eeType=JVM,*");
    Set s = mejb.queryNames(jvmQuery, null);
    ObjectName jvmMBean = (ObjectName) s.iterator().next(); boolean hasStats = ((Boolean) mejb.getAttribute(jvmMBean,
            "statisticsProvider")).booleanValue(); if (hasStats) {
        JVMStats stats = (JVMStats) mejb.getAttribute(jvmMBean,
                                                      "stats");
        String[] statisticNames = stats.getStatisticNames();
        if (Arrays.asList(statisticNames).contains("heapSize")) {
            System.out.println("Heap size: " + stats.getHeapSize());
        }
    }
    
    

    The queryNames() method first queries the JVM MBean. The getAttribute method gets the statisticsProvider attribute and determine if this MBean provides statistics. If the MBean does, the example accesses the stats attribute, and then invokes the getHeapSize() method to get the heap size.

 

Results

The strength of this example is that the example can run on any vendor appserver. It demonstrates that an MBean can optionally implement defined interfaces, in this case the StatisticsProvider interface. If an MBean implements the StatisticsProvider interface, you can see if an appserver supports a particular statistic, in this case the heap size. The specification defines the heap size, although this value is optional. If the appserver supports the heap size, you can display the heap size for the JVM.



Administrative programs for multiple J2EE appservers