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Sun Java System Application Server Standard and Enterprise Edition 7 2004Q2 Developer's Guide 

Chapter 6
Developing Lifecycle Listeners

Lifecycle listener modules provide a means of running short or long duration Java-based tasks within the application server environment, such as instantiation of singletons or RMI servers. These modules are automatically initiated at server startup and are notified at various phases of the server life cycle.

The following sections describe how to create and use a lifecycle module:

Server Life Cycle Events

A lifecycle module listens for and performs its tasks in response to the following events in the server life cycle:

These events are defined in the LifecycleEvent class.

The lifecycle modules that listen for these events implement the LifecycleListener interface and are configured in the server.xml file.

The LifecycleListener Interface

To create a lifecycle module is to configure a customized class that implements the com.sun.appserv.server.LifecycleListener interface. You can create and simultaneously execute multiple lifecycle modules.

The LifecycleListener interface defines this method:

A sample implementation of the LifecycleListener interface is the file, which you can use for testing lifecycle events:

package com.sun.appserv.server;

import java.util.Properties;

 * LifecycleListenerImpl is a dummy implementation for the LifecycleListener
 * interface.This implementaion stubs out various lifecycle interface methods.

public class LifecycleListenerImpl implements LifecycleListener {

  /** receive a server lifecycle event
   * @param event associated event
   * @throws <code>ServerLifecycleException</code> for exceptional condition.
   * Configure this module as a lifecycle-module in server.xml:
   * <applications>
   *    <lifecycle-module name="test"
   *          class-name="com.sun.appserv.server.LifecycleListenerImpl"
   *          is-failure-fatal="false">
   *      <property name="foo" value="fooval"/>
   *    </lifecycle-module>
   * </applications>
   * Set<code>is-failure-fatal</code>in server.xml to <code>true</code> for
   * fatal conditions.
  public void handleEvent(LifecycleEvent event) throws ServerLifecycleException
    LifecycleEventContext context = event.getLifecycleEventContext();

    context.log("got event" + event.getEventType() + " event data: "
      + event.getData());

    Properties props;

    if (LifecycleEvent.INIT_EVENT == event.getEventType()) {
      context.log("LifecycleListener: INIT_EVENT");

      props = (Properties) event.getData();

      // handle INIT_EVENT

    if (LifecycleEvent.STARTUP_EVENT == event.getEventType()) {
      context.log("LifecycleListener: STARTUP_EVENT");

      // handle STARTUP_EVENT

    if (LifecycleEvent.READY_EVENT == event.getEventType()) {

      context.log("LifecycleListener: READY_EVENT");

      // handle READY_EVENT

    if (LifecycleEvent.SHUTDOWN_EVENT== event.getEventType()) {
      context.log("LifecycleListener: SHUTDOWN_EVENT");

      // handle SHUTDOWN_EVENT

    if (LifecycleEvent.TERMINATION_EVENT == event.getEventType()) {
      context.log("LifecycleListener: TERMINATE_EVENT");

      // handle TERMINATION_EVENT

The LifecycleEvent Class

The com.sun.appserv.server.LifecycleEvent class defines a server life cycle event. The following methods are associated with the event:

A LifecycleEvent instance is passed to the LifecycleListener.handleEvent method.

The Server Lifecycle Event Context

The com.sun.appserv.server.LifecycleEventContext interface exposes runtime information about the server. The lifecycle event context is created when the LifecycleEvent class is instantiated at server initialization. The LifecycleEventContext interface defines these methods:

Assembling and Deploying a Lifecycle Module

You assemble a lifecycle module as described in “Assembling a Lifecycle Module” on page 88. You deploy a lifecycle module as described in “Deploying a Lifecycle Module” on page 100.

During lifecycle module deployment, a lifecycle-module element is created in the server.xml file. You can edit this file to change its configuration. The property subelement allows you to specify input parameters. For example:

<lifecycle-module             name="customStartup"
  <description>custom startup module to do my tasks</description>
  <property name="rmiServer" value="acme1:7070" />
  <property name="timeout" value="30" />

Note that if is-failure-fatal is set to true (the default is false), lifecycle module failure prevents server initialization or startup, but not shutdown or termination.

For more information about the server.xml file, see the Sun Java System Application Server Administrator’s Configuration File Reference.

After you deploy a lifecycle module, you must restart the server to activate it. The server instantiates it and registers it as a lifecycle event listener at server initialization.

Considerations for Lifecycle Modules

The resources allocated during initialization or startup should be freed during shutdown or termination. The lifecycle module classes are called synchronously from the main server thread, therefore it is important to ensure that these classes don’t block the server. Lifecycle modules may create threads if appropriate, but these threads must be stopped in the shutdown and termination phases.

The LifeCycleModule Classloader is the parent classloader for lifecycle modules. Each lifecycle module’s classpath in server.xml is used to construct its classloader. All the support classes needed by a lifecycle module must be available to the LifeCycleModule Classloader or its parent, the Shared Classloader. (The Shared Classloader loads server-wide resources.)

You must ensure that the server.policy file is appropriately set up, or a lifecycle module trying to perform a System.exec() may cause a security access violation. For details, see “The server.policy File” on page 57.

The configured properties for a lifecycle module are passed as properties in the INIT_EVENT. The JNDI naming context is not available in the INIT_EVENT. If a lifecycle module requires the naming context, it can get this in the STARTUP_EVENT, READY_EVENT, or SHUTDOWN_EVENT.

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Copyright 2004 Sun Microsystems, Inc. All rights reserved.