JMX Features

JMX Features

• A Management Client (as well as any MBean) can

  JMX Features

  • *Register MBeans with the MBeanServer (i.e. add them to the MBean repository).
  • *Create and register an MBean with the MBeanServer.
  • *Remove an MBean from the MBeanServer.
  • *View the published methods of an MBean (these methods are called Operations and Attributes), along with a description of each published method.
  • *Invoke the published methods of an MBean.
  • Receive notifications when an MBean triggers or throws an event (which is just like throwing a Throwable).
  • List (a.k.a. "query") subsets of MBeans using JMX domains, wildcards and/or name/value attribute pairs.
• Create, initialize and register MBeans by specifying the class file location and initialization parameters in an Mlet file.
• Generate JMX notifications with a Timer Service.
• Enforce and maintain relationships (like one-to-many) of subsets of MBeans.
• Control local and remote access to MBeans.
• Precise control and fine-tuning of class loading.
• *Remote JMX Clients that work just like Local JMX Clients after you get a MBeanServerConnection of an MBeanServer.

• I cover MBean name search/queries trivially because that's all that is needed. If you want complex search capabilities, you can do much better with existing Java mechanisms than the poorly designed JMX query mechanisms.
• Narrowing down subsets of MBeans with JMX-specific methods is easy to figure out from the API, and I have yet to run across a case where an application would suffer by retrieving all of the MBean names and using Java 1.0 features to choose the names that you want.
• Notifications are definitely important for dynamic applications with inter-relations among MBeans. Most importantly, to update persistent storage upon MBean removal or registration. Originally, I didn't give high priority to documenting them since the early R.I. releases didn't fully implement it, and not until recently did Sun provide examples for them. I do intend to document Notifications when I have time.
• Sun's Mlets aren't working right for me any more, and the error handling is REALLY BAD. Every substantial JMX product I have seen uses their own method for loading MBeans from a xml file list. Since most people are not satisfied with Mlets, I recommend that, if you want to load MBeans from a file list, you see what your JMX product or JMX distribution has to offer.
• Timer Service and relationship control are not covered by Sun's examples or tutorials, and I get the feeling that these features may change in the future. I am also not convinced that the goals of these features are not handled better by other existing technologies.
• Access control and class loading are advanced features that are explained adequately in the main JMX Spec.