JMX technology provides a tiered architecture which consists managed resources and management applications can be integrated in the plug-and-play approach as shown in Figure given below. A given resource is instrumented by one or more Java objects known as Managed Beans, which are registered in a core managed object server known as the MBean server. This server acts as a management agent and can run on most Java-enabled machine.

This tier consist components that enable management applications to communicate with JMX agents. It provides the interfaces for implementing JMX managers, and defines the management interfaces and components that operate on JMX agents. Such components provide an interface for a management application to interact with an JMX agent and its JMX manageable resources through a connector, and also expose a management view of a JMX agent and its MBeans by mapping their semantic meaning into the constructs of a data-rich protocol like HTML.

JMX comprises a separate package for each tier of the management architecture. The instrumentation tier will be free, and other tiers can be built from public specifications implementations available under Sun Community Source License.

This tier contains the JMX agents which is used to expose the MBeans. It provides a specification for implementing agents, which control the resources and make them available to remote management applications. JMX Agents are usually located on the same machine as the resources they manage, but this is not a requirement. For handling MBeans the JMX agent consists of an MBean server and a set of services. Managers access an agent's MBeans and use the provided services through a protocol adaptor or connector. But note that JMX agents do not require knowledge of the remote management applications that use them.

The MBean Server and Agent Services are the main components of agent level.

• MBean Server: MBean Server are the registry of objects that are exposed to management operations in an JMX agent. Any object registered with the MBean server becomes visible to management applications. However, note that the MBean server only exposes an MBean's management interface and never it interact with direct object reference. Any resources that you want to manage from outside the agent's JVM must be registered as an MBean in the server. The server also provides a standardized interface for accessing MBeans within the same JVM, giving local objects all the benefits of manipulating manageable resources. MBeans can be registered and instantiated by another MBean, the JMX agent itself, or a remote management application through the distributed services. When you register an MBean, you must assign it a unique object name, which is used by the management application to identify the object on which to perform a management operation.
  
  

• Agent Services: Objects that can perform management operations on the MBeans are registered in the MBean server. By including management intelligence in the agent, JMX helps you build more powerful management solutions. The JMX API defines the following Agent Services available in J2SE 5.0:
  
  

  • Dynamic Class loader: Through the management applet (m-let) service, retrieves and instantiates new classes and native libraries from an arbitrary network location.

  
  
  

  • Monitors: Observe the numerical or string value of an attribute of several MBeans and can notify other objects of several types of changes in the target.

  
  
  

  • Timers: Provide a scheduling mechanism based on a one-time alarm-clock notification or on a repeated, periodic notification.

  
  
  

  • The relation service: Defines associations between MBeans and enforces the cardinality of the relation based on predefined relation types.

  
  
  

Instrumental Level contains MBeans and their manageable resources. It provides a specification for implementing JMX technology-manageable resources, which can be service, device, an application or user. A resource is manageable if it is developed in Java and has been instrumented so that it can be managed by JMX-compliant applications. A resource is instrumented by one or more MBeans that are either standard or dynamic. Standard MBeans are Java objects that conform to certain design patterns (e.g. they must have a constructor etc.). A dynamic MBean conforms to a specific interface that offers more flexibility at runtime. The instrumentation of a resource allows it to be manageable at the agent level; however, note that MBeans do not require knowledge of the JMX agent with which they operate. In other words, any JMX-manageable resource can use any JMX agent that offers the services it requires.

The key Components at the instrumentation level are the MBeans, the notification model, and the MBean metadata classes.

• MBeans: An MBean is a Java object that implements a specific interface. The management interface of an MBean is represented as: (a) valued attributes that can be accessed; (b) operations that can be invoked; (c) notifications that can be emitted; and (d) the constructors. There are four types of MBeans:
  
  

  • Standard MBeans: Their management interface is described by their method names and simple to design.

  
  
  

  • Dynamic MBeans: They expose their management interfaces at runtime for greatest flexibility and implement a specific interface.

  
  
  

  • Open MBean: Dynamic MBeans that rely on basic data types for universal manageability; they are self-describing.

  
  
  

  • Model MBeans: Dynamic MBeans that are fully configurable and self described at runtime. They provide a generic MBean class with default behavior for dynamic instrumentation of resources.

  
  
  

• Notification Model: Based on the Java event model JMX technology defines a generic notification model. It lets developers build proactive management solutions. Using notifications, JMX agents and MBeans can send critical information to interested parties such as management applications or other MBeans.
  
  

• MBean Metadata Classes: These classes contain the structures to describe all components of an MBean's management interface: its operations, notification, attributes and constructors. For each of these, the metadata include a name, a description and its particular characteristics (for example, an attribute is read- write or both; for an operation, the signature of its parameter and return types).