Summary

The Geronimo debug console, while not a fancy GUI tool, is a hardcore administrator’s tool that will display information on all the objects managed by the Geronimo kernel.

Since the objects expose their properties via JMX, JDK 1.5’s GUI JMX console called jconsole can also be used to display managed object information.

The Geronimo kernel manages components called GBeans. Every GBean can be externally manageable if the designer of the GBean exposes Java Management Extension (JMX) attributes or operations.

JMX specifies how Java-based software components, servers, or devices can be managed by network-management applications. The JMX model has three levels: Instrumentation, Agent, and Distributed Services.

At the JMX instrumentation level, MBeans are created. An MBean provides a management interface for a software component, service, or device. MBeans are created without concern for the Agent level. At the Agent level, an MBean server aggregates MBeans and interfaces them to external network-management application or applications at the Distributed Services level.

JSR-77 is a J2EE management specification that uses JMX to specify how J2EE servers and software components can be made manageable. Specifically, JSR-77 enables compatible clients (management applications) to be created and used on any compatible server. JSR-77 clients obtain MBean information on managed component via a Management EJB (MEJB).

The Geronimo debug console is a Web application running in Geronimo that is actually a JSR-77 client. It queries the MEJB, implemented by Geronimo, for Geronimo component information.

JSR-77 specifies a standard J2EE object naming convention that reveals the hierarchical relationship between J2EE components. This convention is used to query for objects using the debug console.

Troubleshooting deployment using the debug console boils down to querying the console using the JSR-77 name pattern to locate a managed object and then viewing the state and/or attributes of the component’s JMX MBean. You have walked through a typical deployment troubleshooting scenario in this chapter.

Moving from a low-level, hardcore tool to a high-level, do-all utility, Chapter 8 looks at the capabilities of the Geronimo Web console.