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Chapter 62. JMX

JMX Component

The JMX component enables consumers to subscribe to an MBean's notifications. The component supports passing the Notification object directly through the exchange or serializing it to XML according to the schema provided within this project. This is a consumer-only component. Exceptions are thrown if you attempt to create a producer for it.

URI Format

The component can connect to the local platform MBean server with the following URI: 
jmx://platform?options
A remote MBean server URL can be specified after the jmx: scheme prefix, as follows: 
jmx:service:jmx:rmi:///jndi/rmi://localhost:1099/jmxrmi?options
You can append query options to the URI in the following format, ?option=value&option=value&....

URI Options

Property Required Default Description
format xml Format for the message body. Either xml or raw. If xml, the notification is serialized to XML. If raw, the raw java object is set as the body.
password Credentials for making a remote connection.
objectDomain Yes The domain of the MBean you are connecting to.
objectName The name key for the MBean you are connecting to. Either this property of a list of keys must be provided (but not both). For more details, see the section called “ObjectName Construction”.
notificationFilter Reference to a bean that implements the NotificationFilter interface. The #beanID syntax should be used to reference the bean in the registry.
handback Value to hand back to the listener when a notification is received. This value will be put into the jmx.handback message header.
testConnectionOnStartup true *Camel 2.11* If true, the consumer will throw an exception when unable to establish the JMX connection upon startup. If false, the consumer will attempt to establish the JMX connection every 'x' seconds until the connection is made - where 'x' is the configured reconnectDelay.
reconnectOnConnectionFailure false *Camel 2.11* If true, the consumer will attempt to reconnect to the JMX server when any connection failure occurs. The consumer will attempt to re-establish the JMX connection every 'x' seconds until the connection is made-- where 'x' is the configured reconnectDelay.
reconnectDelay 10 *Camel 2.11* The number of seconds to wait before retrying creation of the initial connection or before reconnecting a lost connection.

ObjectName Construction

The URI must always have the objectDomain property. In addition, the URI must contain either objectName or one or more properties that start with key.

Domain with Name property

When the objectName property is provided, the following constructor is used to build the ObjectName instance for the MBean: 
ObjectName(String domain, String key, String value)
The key value in the preceding constructor must be name and the value is the value of the objectName property.

Domain with Hashtable

ObjectName(String domain, Hashtable<String,String> table)
The Hashtable is constructed by extracting properties that start with key. The properties will have the key prefix stripped prior to building the Hashtable. This allows the URI to contain a variable number of properties to identify the MBean.

Example

from("jmx:platform?objectDomain=jmxExample&key.name=simpleBean").
        to("log:jmxEvent");

Full example

A complete example using the JMX component is available under the examples/camel-example-jmx directory.

Monitor Type Consumer

Available as of Camel 2.8 One popular use case for JMX is creating a monitor bean to monitor an attribute on a deployed bean. This requires writing a few lines of Java code to create the JMX monitor and deploy it. As shown below: 
 CounterMonitor monitor = new CounterMonitor();
 monitor.addObservedObject(makeObjectName("simpleBean"));
 monitor.setObservedAttribute("MonitorNumber");
 monitor.setNotify(true);
 monitor.setInitThreshold(1);
 monitor.setGranularityPeriod(500);
 registerBean(monitor, makeObjectName("counter"));
 monitor.start();
The 2.8 version introduces a new type of consumer that automatically creates and registers a monitor bean for the specified objectName and attribute. Additional endpoint attributes allow the user to specify the attribute to monitor, type of monitor to create, and any other required properties. The code snippet above is condensed into a set of endpoint properties. The consumer uses these properties to create the CounterMonitor, register it, and then subscribe to its changes. All of the JMX monitor types are supported.

Example

from("jmx:platform?objectDomain=myDomain&objectName=simpleBean&" + 
     "monitorType=counter&observedAttribute=MonitorNumber&initThreshold=1&" +
     "granularityPeriod=500").to("mock:sink");
The example above will cause a new Monitor Bean to be created and depoyed to the local mbean server that monitors the MonitorNumber attribute on the simpleBean. Additional types of monitor beans and options are detailed below. The newly deployed monitor bean is automatically undeployed when the consumer is stopped.

URI Options for Monitor Type

property type applies to description
monitorType enum all one of the counters, guage, string
observedAttribute string all the attribute being observed
granularityPeriod long all granularity period (in millis) for the attribute being observed. As per JMX, default is 10 seconds
initThreshold number counter initial threshold value
offset number counter offset value
modulus number counter modulus value
differenceMode boolean counter, gauge true if difference should be reported, false for actual value
notifyHigh boolean gauge high notification on/off switch
notifyLow boolean gauge low notification on/off switch
highThreshold number gauge threshold for reporting high notification
lowThreshold number gauge threshold for reporting low notificaton
notifyDiffer boolean string true to fire notification when string differs
notifyMatch boolean string true to fire notification when string matches
stringToCompare string string string to compare against the attribute value
The monitor style consumer is only supported for the local mbean server. JMX does not currently support remote deployment of mbeans without either having the classes already remotely deployed or an adapter library on both the client and server to facilitate a proxy deployment.