18.2.2.2 JmxMBeanEntryImpl

As mentioned previously, the JmxMBeanEntryImpl objects keep the jmxMBeanAttrTable updated. Example 18–9 and Example 18–10 show how JmxMBeanEntryImpl changes the status of rows, activates rows, and destroys them.

Example 18–9 Changing the Row Status

[...]

public synchronized void setJmxMBeanRowStatus(EnumJmxMBeanRowStatus x) 
	   throws SnmpStatusException {
	   switch (x.intValue()) {
	   case EnumRowStatus.active:
	       if (! (JmxMBeanRowStatus.intValue() == EnumRowStatus.active))
		        activate();
	       break;
	   case EnumRowStatus.notReady:
	       break;
	   case EnumRowStatus.notInService:
	       super.setJmxMBeanRowStatus(x);
	       break;
	   case EnumRowStatus.destroy:
	       destroy();
	       break;
	   default:
	       throw new SnmpStatusException(SnmpStatusException.
					                          snmpRspInconsistentValue);
	   }
}

[...]

The setJmxMBeanRowStatus method shown above is called by the SNMP runtime when the row is created remotely. It is also called explicitly by JmxMBeanEntryImpl when the row is created after receiving an MBean server notification.

Example 18–10 Activating and Destroying Rows

private void activate() throws SnmpStatusException {
	   if ((remoteCreation) && (mbean == null || name == null))
	       throw new SnmpStatusException(SnmpStatusException.snmpRspGenErr);
	   try {

	        if (remoteCreation) {
		         myGroup.registerMBean(mbean,name,this);
		         initJmxMBean(name);
		         remoteCreation = false;
		         mbean = null;
	        } 

	        exposedAttrCount = myGroup.addAttributes(name,this);
	        if (Boolean.getBoolean("info")) 
		         System.out.println(name.toString()+ ": added " + 
				                      exposedAttrCount
				                      + " attribute(s).");
	        JmxMBeanRowStatus = 
		         new EnumJmxMBeanRowStatus(EnumRowStatus.active);
	   } catch (Exception x) {
	        SnmpStatusException sn = 
		         new SnmpStatusException(SnmpStatusException.snmpRspGenErr);
	        sn.initCause(x);
	        throw sn;
	   }
}

private void destroy() throws SnmpStatusException {
  	try {
	       JmxMBeanRowStatus = 
		        new EnumJmxMBeanRowStatus(EnumRowStatus.notInService);
	       if (name != null && remoteDeletion)
		        myGroup.unregisterMBean(name,this);
	       remoteCreation = false;
	       mbean = null;	
	       if (name != null) 
		        myGroup.removeAttributes(name,this);
	       attrList = null;
	   } catch (Exception x) {
	       SnmpStatusException sn = 
		        new SnmpStatusException(SnmpStatusException.snmpRspGenErr);
	       sn.initCause(x);
	       throw sn;
	   }
}

Example 18–10 shows the activate and destroy methods defined by JmxMBeanEntryImpl. The activate method verifies first of all whether the row was created remotely or locally, and acts differently depending on the answer. If the row was created remotely by calling the createFromRemote method, the row entry registers the requested MBean in the MBean. If the row is created locally, this means that the request to create the row was made by an existing registered MBean, so there is no need to register it again in the MBean server.

The destroy method is created when the row is removed, either locally by handleMBeanServerNotification or remotely. The destroy method is called by removeEntryCb, which itself is called when the row is removed from the table, whether remotely or locally.