Architecture of the JMX Technology

The JMX technology can be divided into three levels, as follows:

• Instrumentation
• JMX agent
• Remote management

Instrumentation

To manage resources using the JMX technology, you must first instrument the resources in the Java programming language. You use Java objects known as MBeans to implement the access to the resources' instrumentation. MBeans must follow the design patterns and interfaces defined in the JMX specification. Doing so ensures that all MBeans provide managed resource instrumentation in a standardized way. In addition to standard MBeans, the JMX specification also defines a special type of MBean called an MXBean. An MXBean is an MBean that references only a pre-defined set of data types. Other types of MBean exist, but this trail will concentrate on standard MBeans and MXBeans.

Once a resource has been instrumented by MBeans, it can be managed through a JMX agent. MBeans do not require knowledge of the JMX agent with which they will operate.

MBeans are designed to be flexible, simple, and easy to implement. Developers of applications, systems, and networks can make their products manageable in a standard way without having to understand or invest in complex management systems. Existing resources can be made manageable with minimum effort.

In addition, the instrumentation level of the JMX specification provides a notification mechanism. This mechanism enables MBeans to generate and propagate notification events to components of the other levels.

JMX Agent

A JMX technology-based agent (JMX agent) is a standard management agent that directly controls resources and makes them available to remote management applications. JMX agents are usually located on the same machine as the resources they control, but this arrangement is not a requirement.

The core component of a JMX agent is the MBean server, a managed object server in which MBeans are registered. A JMX agent also includes a set of services to manage MBeans, and at least one communications adaptor or connector to allow access by a management application.

When you implement a JMX agent, you do not need to know the semantics or functions of the resources that it will manage. In fact, a JMX agent does not even need to know which resources it will serve because any resource instrumented in compliance with the JMX specification can use any JMX agent that offers the services that the resource requires. Similarly, the JMX agent does not need to know the functions of the management applications that will access it.

Remote Management

JMX technology instrumentation can be accessed in many different ways, either through existing management protocols such as the Simple Network Management Protocol (SNMP) or through proprietary protocols. The MBean server relies on protocol adaptors and connectors to make a JMX agent accessible from management applications outside the agent's Java Virtual Machine (Java VM).

Each adaptor provides a view through a specific protocol of all MBeans that are registered in the MBean server. For example, an HTML adaptor could display an MBean in a browser.

Connectors provide a manager-side interface that handles the communication between manager and JMX agent. Each connector provides the same remote management interface through a different protocol. When a remote management application uses this interface, it can connect to a JMX agent transparently through the network, regardless of the protocol. The JMX technology provides a standard solution for exporting JMX technology instrumentation to remote applications based on Java Remote Method Invocation (Java RMI).

What is JMX

The JMX technology provides developers with a flexible means to instrument Java technology-based applications (Java applications), create smart agents, implement distributed management middleware and managers, and smoothly integrate these solutions into existing management and monitoring systems.

• The JMX technology enables Java applications to be managed without heavy investment.
  A JMX technology-based agent (JMX agent) can run on most Java technology-enabled devices. Consequently, Java applications can become manageable with little impact on their design. A Java application needs only to embed a managed object server and make some of its functionality available as one or several managed beans (MBeans) registered in the object server. That is all it takes to benefit from the management infrastructure.
• The JMX technology provides a standard way to manage Java applications, systems, and networks.
  For example, the Java Platform, Enterprise Edition (Java EE) 5 Application Server conforms to the JMX architecture and consequently can be managed by using JMX technology.
• The JMX technology can be used for out-of-the-box management of the Java VM.
  The Java Virtual Machine (Java VM) is highly instrumented using the JMX technology. You can start a JMX agent to access the built-in Java VM instrumentation, and thereby monitor and manage a Java VM remotely.
• The JMX technology provides a scalable, dynamic management architecture.
  Every JMX agent service is an independent module that can be plugged into the management agent, depending on the requirements. This component-based approach means that JMX solutions can scale from small-footprint devices to large telecommunications switches and beyond. The JMX specification provides a set of core agent services. Additional services can be developed and dynamically loaded, unloaded, or updated in the management infrastructure.
• The JMX technology leverages existing standard Java technologies.
  Whenever needed, the JMX specification references existing Java specifications, for example, the Java Naming and Directory Interface (J.N.D.I.) API.
• The JMX technology-based applications (JMX applications) can be created from a NetBeans IDE module.
  You can obtain a module from the NetBeans Update Center (select Tools -> Update Center in the NetBeans interface) that enables you to create JMX applications by using the NetBeans IDE. This reduces the cost of development of JMX applications.
• The JMX technology integrates with existing management solutions and emerging technologies.
  The JMX APIs are open interfaces that any management system vendor can implement. JMX solutions can use lookup and discovery services and protocols such as Jini network technology and the Service Location Protocol (SLP).