JBoss.org Community Documentation
In version 2 of the XMBean we add support for persistence of the XMBean attributes. The updated XMBean deployment descriptor is given below.
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE mbean PUBLIC
"-//JBoss//DTD JBOSS XMBEAN 1.0//EN"
"http://www.jboss.org/j2ee/dtd/jboss_xmbean_1_0.dtd">
<mbean>
<description>The JNDIMap XMBean Example Version 2</description>
<descriptors>
<persistence persistPolicy="OnUpdate" persistPeriod="10"
persistLocation="${jboss.server.data.dir}" persistName="JNDIMap.ser"/>
<currencyTimeLimit value="10"/>
<state-action-on-update value="keep-running"/>
<persistence-manager value="org.jboss.mx.persistence.ObjectStreamPersistenceManager"/>
</descriptors> <class>org.jboss.test.jmx.xmbean.JNDIMap</class>
<constructor>
<description>The default constructor</description>
<name>JNDIMap</name>
</constructor>
<!-- Attributes -->
<attribute access="read-write" getMethod="getJndiName" setMethod="setJndiName">
<description>
The location in JNDI where the Map we manage will be bound
</description>
<name>JndiName</name>
<type>java.lang.String</type>
<descriptors>
<default value="inmemory/maps/MapTest"/>
</descriptors>
</attribute>
<attribute access="read-write" getMethod="getInitialValues"
setMethod="setInitialValues">
<description>The array of initial values that will be placed into the
map associated with the service. The array is a collection of
key,value pairs with elements[0,2,4,...2n] being the keys and
elements [1,3,5,...,2n+1] the associated values</description>
<name>InitialValues</name>
<type>[Ljava.lang.String;</type>
<descriptors>
<default value="key0,value0"/>
</descriptors>
</attribute>
<!-- Operations -->
<operation>
<description>The start lifecycle operation</description>
<name>start</name>
</operation>
<operation>
<description>The stop lifecycle operation</description>
<name>stop</name>
</operation>
<operation impact="ACTION">
<description>Put a value into the nap</description>
<name>put</name>
<parameter>
<description>The key the value will be store under</description>
<name>key</name>
<type>java.lang.Object</type>
</parameter>
<parameter>
<description>The value to place into the map</description>
<name>value</name>
<type>java.lang.Object</type>
</parameter>
</operation>
<operation impact="INFO">
<description>Get a value from the map</description>
<name>get</name>
<parameter>
<description>The key to lookup in the map</description>
<name>get</name>
<type>java.lang.Object</type>
</parameter>
<return-type>java.lang.Object</return-type>
</operation>
<!-- Notifications -->
<notification>
<description>The notification sent whenever a value is get into the map
managed by the service</description>
<name>javax.management.Notification</name>
<notification-type>org.jboss.book.jmx.xmbean.JNDIMap.get</notification-type>
</notification>
<notification>
<description>The notification sent whenever a value is put into the map
managed by the service</description>
<name>javax.management.Notification</name>
<notification-type>org.jboss.book.jmx.xmbean.JNDIMap.put</notification-type>
</notification>
</mbean>
Build, deploy and test the version 2 XMBean as follows:
[examples]$ ant -Dchap=jmx -Dex=xmbean2 -Djboss.deploy.conf=rmi-adaptor run-example
...
run-examplexmbean2:
[java] JNDIMap Class: org.jboss.mx.modelmbean.XMBean
[java] JNDIMap Operations:
[java] + void start()
[java] + void stop()
[java] + void put(java.lang.Object chap2.xmbean:service=JNDIMap,java.lang.Object cha
p2.xmbean:service=JNDIMap)
[java] + java.lang.Object get(java.lang.Object chap2.xmbean:service=JNDIMap)
[java] + java.lang.String getJndiName()
[java] + void setJndiName(java.lang.String chap2.xmbean:service=JNDIMap)
[java] + [Ljava.lang.String; getInitialValues()
[java] + void setInitialValues([Ljava.lang.String; chap2.xmbean:service=JNDIMap)
[java] handleNotification, event: null
[java] key=key10, value=value10
[java] handleNotification, event: javax.management.Notification[source=chap2.xmbean:s
ervice=JNDIMap,type=org.jboss.chap2.xmbean.JNDIMap.put,sequenceNumber=7,timeStamp=10986326
93716,message=null,userData=null]
[java] JNDIMap.put(key1, value1) successful
[java] handleNotification, event: javax.management.Notification[source=chap2.xmbean:s
ervice=JNDIMap,type=org.jboss.chap2.xmbean.JNDIMap.get,sequenceNumber=8,timeStamp=10986326
93857,message=null,userData=null]
[java] JNDIMap.get(key0): null
[java] handleNotification, event: javax.management.Notification[source=chap2.xmbean:s
ervice=JNDIMap,type=org.jboss.chap2.xmbean.JNDIMap.get,sequenceNumber=9,timeStamp=10986326
93896,message=null,userData=null]
[java] JNDIMap.get(key1): value1
[java] handleNotification, event: javax.management.Notification[source=chap2.xmbean:s
ervice=JNDIMap,type=org.jboss.chap2.xmbean.JNDIMap.put,sequenceNumber=10,timeStamp=1098632
693925,message=null,userData=null]
There is nothing manifestly different about this version of the XMBean at this point because we have done nothing to test that changes to attribute value are actually persisted. Perform this test by running example xmbean2a several times:
[examples] ant -Dchap=jmx -Dex=xmbean2a run-example
...
[java] InitialValues.length=2
[java] key=key10, value=value10
[examples] ant -Dchap=jmx -Dex=xmbean2a run-example
...
[java] InitialValues.length=4
[java] key=key10, value=value10
[java] key=key2, value=value2
[examples] ant -Dchap=jmx -Dex=xmbean2a run-example
...
[java] InitialValues.length=6
[java] key=key10, value=value10
[java] key=key2, value=value2
[java] key=key3, value=value3
The org.jboss.book.jmx.xmbean.TestXMBeanRestart used in this example obtains the current InitialValues attribute setting, and then adds another key/value pair to it. The client code is shown below.
package org.jboss.book.jmx.xmbean;
import javax.management.Attribute;
import javax.management.ObjectName;
import javax.naming.InitialContext;
import org.jboss.jmx.adaptor.rmi.RMIAdaptor;
/**
* A client that demonstrates the persistence of the xmbean
* attributes. Every time it run it looks up the InitialValues
* attribute, prints it out and then adds a new key/value to the
* list.
*
* @author Scott.Stark@jboss.org
* @version $Revision: 1.9 $
*/
public class TestXMBeanRestart
{
/**
* @param args the command line arguments
*/
public static void main(String[] args) throws Exception
{
InitialContext ic = new InitialContext();
RMIAdaptor server = (RMIAdaptor) ic.lookup("jmx/rmi/RMIAdaptor");
// Get the InitialValues attribute
ObjectName name = new ObjectName("j2eechap2.xmbean:service=JNDIMap");
String[] initialValues = (String[])
server.getAttribute(name, "InitialValues");
System.out.println("InitialValues.length="+initialValues.length);
int length = initialValues.length;
for (int n = 0; n < length; n += 2) {
String key = initialValues[n];
String value = initialValues[n+1];
System.out.println("key="+key+", value="+value);
}
// Add a new key/value pair
String[] newInitialValues = new String[length+2];
System.arraycopy(initialValues, 0, newInitialValues,
0, length);
newInitialValues[length] = "key"+(length/2+1);
newInitialValues[length+1] = "value"+(length/2+1);
Attribute ivalues = new
Attribute("InitialValues", newInitialValues);
server.setAttribute(name, ivalues);
}
}
At this point you may even shutdown the JBoss server, restart it and then rerun the initial example to see if the changes are persisted across server restarts:
[examples]$ ant -Dchap=jmx -Dex=xmbean2 run-example
...
run-examplexmbean2:
[java] JNDIMap Class: org.jboss.mx.modelmbean.XMBean
[java] JNDIMap Operations:
[java] + void start()
[java] + void stop()
[java] + void put(java.lang.Object chap2.xmbean:service=JNDIMap,java.lang.Object cha
p2.xmbean:service=JNDIMap)
[java] + java.lang.Object get(java.lang.Object chap2.xmbean:service=JNDIMap)
[java] + java.lang.String getJndiName()
[java] + void setJndiName(java.lang.String chap2.xmbean:service=JNDIMap)
[java] + [Ljava.lang.String; getInitialValues()
[java] + void setInitialValues([Ljava.lang.String; chap2.xmbean:service=JNDIMap)
[java] handleNotification, event: null
[java]
key=key10, value=value10
[java]
key=key2, value=value2
[java]
key=key3, value=value3
[java]
key=key4, value=value4
[java] handleNotification, event: javax.management.Notification[source=chap2.xmbean:s
ervice=JNDIMap,type=org.jboss.book.jmx.xmbean.JNDIMap.put,sequenceNumber=3,timeStamp=10986
33664712,message=null,userData=null]
[java] JNDIMap.put(key1, value1) successful
[java] handleNotification, event: javax.management.Notification[source=chap2.xmbean:s
ervice=JNDIMap,type=org.jboss.book.jmx.xmbean.JNDIMap.get,sequenceNumber=4,timeStamp=10986
33664821,message=null,userData=null]
[java] JNDIMap.get(key0): null
[java] handleNotification, event: javax.management.Notification[source=chap2.xmbean:s
ervice=JNDIMap,type=org.jboss.book.jmx.xmbean.JNDIMap.get,sequenceNumber=5,timeStamp=10986
33664860,message=null,userData=null]
[java] JNDIMap.get(key1): value1
[java] handleNotification, event: javax.management.Notification[source=chap2.xmbean:s
ervice=JNDIMap,type=org.jboss.book.jmx.xmbean.JNDIMap.put,sequenceNumber=6,timeStamp=10986
33664877,message=null,userData=null]
[java] handleNotification, event: javax.management.Notification[source=chap2.xmbean:s
ervice=JNDIMap,type=org.jboss.book.jmx.xmbean.JNDIMap.put,sequenceNumber=7,timeStamp=10986
33664895,message=null,userData=null]
[java] handleNotification, event: javax.management.Notification[source=chap2.xmbean:s
ervice=JNDIMap,type=org.jboss.book.jmx.xmbean.JNDIMap.put,sequenceNumber=8,timeStamp=10986
33664899,message=null,userData=null]
[java] handleNotification, event: javax.management.Notification[source=chap2.xmbean:s
ervice=JNDIMap,type=org.jboss.book.jmx.xmbean.JNDIMap.put,sequenceNumber=9,timeStamp=10986
33665614,message=null,userData=null]
You see that the last InitialValues attribute setting is in fact visible.