JMX using Spring

JMX aims to create standard API's for managing and monitoring java applications.

Managing - changing values at runtime.

Monitoring - Reporting certain conditions.

Mbean -is a java bean with a management interface.

Mbean can expose attributes(through getters and setters) or any opertaions.Management interface can be defined statically or at runtime through interfaces.MBean Server acts as a broker between interacting beans or beans and remote clients.

Mbean server maintains a key to all registered means which is called as object name.The default protocol used is RMI , but can be changed to SOAP or Hessian.

Using raw JMX APi's is difficult , spring simplifies this.

Use the following configuration to create a MBeanServer. This will be required normally only if we are running standalone code.Else most of the containers like tomcat or spring dm provide the default MBeanServer which can be used to register the Mbeans.

<bean id="MBeanServer" class="org.springframework.jmx.support.MBeanServerFactoryBean">
<property name="locateExistingServerIfPosssible" value="true">
</bean>

Configuration to register a bean as MBean to MBeanServer.

<bean id="jmsSample" class="com.pg.MonitorService"></bean>

<bean class="org.springframework.jmx.export.MBeanExporter">
<property name="beans">
<util:map>
<entry key="service:name=jmsSample" value-ref="jmsSample" />
</util:map>
</property>

By this all methods and attributes of this can be accesed using jconsole. Sometimes this may not be what we want .we would want to control the set of operations which are visible through JMX.

The Spring MbeanExporter allows the following stratergies

1. ObjectnamingStratergy - this will help in identifying the mbean in the jconsole.

• a. KeyNamingStratergy(Default) - key passed will become the name
• b. IdentityNamingStratergy -generates a object name dynamically
• c. MetaDataNamingStratergy - reads object name from source level meta-data (annotations)

2. MBeanInfoAssembler

When we want to control what we are exposing through JMX this is the better approach

• SimpleReflectiveMbeanInfoAssembler -Default -Exposes all public methods and properties
• MethodNameBasedMbeanInfoAssembler Methods can be configured through spring xmls which will be exposed through JMX.
• MetadataMBeanInfoAssembler what needs to be exposed is controlled using source level annotations.
• InterfaceBasedMBeanInfoAssembler

a. Using managed Interfaces property

<bean class="org.springframework.jmx.export.MBeanExporter">
<property name="beans">
<util:map>
<entry key="service:name=jmsSample" value-ref="jmsSample" />
</util:map>
</property>
<property name="assembler">
<bean
class="org.springframework.jmx.export.assembler.InterfaceBasedMBeanInfoAssembler">
<property name="managedInterfaces">
<value>com.pg.IService</value>
</property>
</bean>
</property>

</bean>

Here the jmsSample bean need not implement teh managedInterface.

b Using interfaceMapping property

<bean class="org.springframework.jmx.export.MBeanExporter">
<property name="beans">
<util:map>
<entry key="service:name=jmsSample" value-ref="jmsSample" />
</util:map>
</property>
<property name="assembler">
<bean
class="org.springframework.jmx.export.assembler.InterfaceBasedMBeanInfoAssembler">
<property name="interfaceMappings">
<util:map>
<entry key="service:name=jmsSampleService" value="com.pg.IService"></entry>
</util:map>
</property>

</property>

</bean>

Thea bean jmsSample must implement the interface mentioned in interfaceMapping property

This API helps in monitoring application using JMX.

http://jamonapi.sourceforge.net/