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 listener module:
These events are defined in the LifecycleEvent class.
The lifecycle modules that listen for these events implement 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:
public void handleEvent(com.sun.appserv.server.LifecycleEvent event) throws ServerLifecycleException
This method returns the data associated with the event.
This method returns the type of the last event, which is INIT_EVENT, STARTUP_EVENT, READY_EVENT, SHUTDOWN_EVENT, or TERMINATION_EVENT.
This method returns the lifecycle event context, described next.
A LifecycleEvent instance is passed to the LifecycleListener.handleEvent method.
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:
This method returns the server startup command-line arguments.
This method returns the server installation root directory.
This method returns the server instance name.
This method returns the initial JNDI naming context. The naming environment for lifecycle modules is installed after the STARTUP_EVENT. A lifecycle module can look up any resource by its jndi-name attribute after the READY_EVENT.
If a lifecycle module needs to look up resources, it can do so after the READY_EVENT. It can use the getInitialContext() method to get the initial context to which all the resources are bound.
In the Administration Console, open the Applications component and go to the Lifecycle Modules page. For details, see the Sun Java System Application Server Enterprise Edition 8.1 2005Q2 Administration Guide.
Use the asadmin create-lifecycle-module command. For details, see the Sun Java System Application Server Enterprise Edition 8.1 2005Q2 Reference Manual.
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.
The resources allocated at initialization or startup should be freed at 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 can create threads if appropriate, but these threads must be stopped in the shutdown and termination phases.
The LifeCycleModule Classloader is the parent class loader for lifecycle modules. Each lifecycle module’s classpath in domain.xml is used to construct its class loader. All the support classes needed by a lifecycle module must be available to the LifeCycleModule Classloader or its parent, the Connector Classloader.
You must ensure that the server.policy file is appropriately set up, or a lifecycle module trying to perform a System.exec() might cause a security access violation. For details, see The server.policy File.
The configured properties for a lifecycle module are passed as properties after the INIT_EVENT. The JNDI naming context is not available before the STARTUP_EVENT. If a lifecycle module requires the naming context, it can get this after the STARTUP_EVENT, READY_EVENT, or SHUTDOWN_EVENT.