1 Introduction to JMX Programming for Message Queue Clients

Resource MBeans

Resource MBeans are associated with individual Message Queue resources of the following types:

• Message brokers

• Connection services

• Connections

• Destinations

• Broker clusters

• Logging

• The Java Virtual Machine (JVM)

Configuration and monitoring functions are implemented by separate MBeans. Each managed resource is associated with a configuration MBean for setting the resource's configuration and a monitor MBean for gathering (typically transient) information about its runtime state. For instance, there is a destination configuration MBean for configuring a destination and a destination monitor MBean for obtaining runtime information about it. In general, each instance of a managed resource has its own pair of MBeans: thus there is a separate destination configuration MBean and destination monitor MBean for each individual destination. (In the case of the Java Virtual Machine, there is only a JVM monitor MBean with no corresponding configuration MBean.)

Configuration MBeans are used to perform such tasks as the following:

• Set a broker's port number

• Set a broker's maximum message size

• Pause a connection service

• Set the maximum number of threads for a connection service

• Purge all messages from a destination

• Set the level of logging information to be written to an output channel

Monitor MBeans are used to obtain runtime information such as the following:

• The current number of connections on a service

• The cumulative number of messages received by a destination since the broker was started

• The current state (running or paused) of a queue destination

• The current number of message producers for a topic destination

• The host name and port number of a cluster's master broker

• The current JVM heap size

Manager MBeans

In addition to the resource MBeans associated with individual resources, there are also manager MBeans for managing some whole categories of resources. These manager MBeans also come in pairs—one for configuration and one for monitoring—for the following resource categories:

• Connection services

• Connections

• Destinations

• Message producers

• Message consumers

• Transactions

Unlike individual resource MBeans, a broker has only one pair of manager MBeans for each whole category of resources: for instance, a single destination manager configuration MBean and a single destination manager monitor MBean. For some categories (connection services, connections, destinations), the manager MBeans exist in addition to the ones for individual resources, and are used to manage the collection of resource MBeans within the category or to perform global tasks that are beyond the scope of individual resource MBeans. Thus, for instance, there is a connection manager configuration MBean and a connection manager monitor MBean in addition to the connection configuration and connection monitor MBeans associated with individual connections. Manager MBeans of this type are used to perform tasks such as the following:

• Get the object names of the connection service monitor MBeans for all available connection services

• Get the total number of current connections

• Destroy a connection

• Create or destroy a destination

• Enable or disable auto-creation of destinations

• Pause message delivery for all destinations

In other cases (message producers, message consumers, transactions), there are no MBeans associated with individual resources and all of the resources in the category are managed through the manager MBeans themselves. The manager MBeans for these categories can be used for such tasks as the following:

• Get the destination name associated with a message producer

• Purge all messages from a durable subscriber

• Commit or roll back a transaction

Object Names

Each individual MBean is designated by an object name belonging to the JMX class ObjectName, which encapsulates a string identifying the MBean. For Message Queue MBeans, the encapsulated name string has the following syntax:

com.sun.messaging.jms.server:property=value[,property=value]*

Table 1-1 shows the possible properties.

Table 1-2 shows the possible values for the object name's type property.

Table 1-3 shows the possible values for the object name's subtype property.

For destination configuration and destination monitor MBeans, the object name's desttype property specifies whether the destination is a point-to-point queue or a publish/subscribe topic. Table 1-4 shows the possible values, which are defined for convenience as static constants in the utility class DestinationType.

For service configuration and service monitor MBeans, the object name's name property identifies the connection service with which the MBean is associated. Table 1-5 shows the possible values.

Table 1-6 shows some example object names.

The object names for each type of Message Queue MBean are given in the relevant sections of Message Queue MBean Reference. All such names are either defined as static constants or returned by static methods in the utility class MQObjectName (see Table 1-7). For instance, the constant

MQObjectName.BROKER_CONFIG_MBEAN_NAME 

is defined as a string representing the object name for a broker configuration MBean, and the method call

MQObjectName. createDestinationMonitor(DestinationType .TOPIC, "MyQueue");

returns the destination monitor MBean object name shown in Table 1-6. Note that, whereas methods such as createDestinationMonitor return an actual object name (that is, an object of class ObjectName) that can be assigned directly to a variable of that type

ObjectNamedestMonitorName 
= MQObjectName. createDestinationMonitor(DestinationType .TOPIC, "Dest");

constants like BROKER_CONFIG_MBEAN_NAME instead represent an ordinary string (class String) that must then be converted into the corresponding object name itself:

ObjectNamebrokerConfigName 
= new ObjectName(MQObjectName.BROKER_CONFIG_MBEAN_NAME);