1. Developing Applications for Oracle WebLogic Server
  2. Programming Application Life Cycle Events

13 Programming Application Life Cycle Events

Learn how to create applications that respond to WebLogic Server application life cycle events.

This chapter includes the following sections:

Understanding Application Life Cycle Events

Application life cycle listener events provide handles on which developers can control behavior during deployment, undeployment, and redeployment. Learn how you can use the application life cycle listener events.

Four application life cycle events are provided with WebLogic Server, which can be used to extend listener, shutdown, and startup classes. These include:

  • Listeners—attachable to any event. Possible methods for Listeners are:

    • public void preStart(ApplicationLifecycleEvent evt) {}

      The preStart event is the beginning of the prepare phase, or the start of the application deployment process.

    • public void postStart(ApplicationLifecycleEvent evt) {}

      The postStart event is the end of the activate phase, or the end of the application deployment process. The application is deployed.

    • public void preStop(ApplicationLifecycleEvent evt) {}

      The preStop event is the beginning of the deactivate phase, or the start of the application removal or undeployment process.

    • public void postStop(ApplicationLifecycleEvent evt) {}

      The postStop event is the end of the remove phase, or the end of the application removal or undeployment process.

  • Shutdown classes only get postStop events.

    Note:

    Application-scoped shutdown classes have been deprecated as of release 9.0 of WebLogic Server. Use life cycle listeners instead.

  • Startup classes only get preStart events.

    Note:

    Application-scoped shutdown classes have been deprecated as of release 9.0 of WebLogic Server. Use life cycle listeners instead.

    For Startup and Shutdown classes, you only implement a main{} method. If you implement any of the methods provided for Listeners, they are ignored.

    No remove{} method is provided in the ApplicationLifecycleListener, because the events are only fired at startup time during deployment (prestart and poststart) and shutdown during undeployment (prestop and poststop).

Parent topic: Programming Application Life Cycle Events

Registering Events in weblogic-application.xml

You must register the application life cycle listener events in the weblogic-application.xml deployment descriptor in order to use them.

See Enterprise Application Deployment Descriptor Elements. Define the following elements:

  • listener—Used to register user defined application life cycle listeners. These are classes that extend the abstract base class weblogic.application.ApplicationLifecycleListener.

  • shutdown—Used to register user-defined shutdown classes.

  • startup—Used to register user-defined startup classes.

Parent topic: Programming Application Life Cycle Events

Programming Basic Life Cycle Listener Functionality

You can create a listener by extending the abstract class (provided with WebLogic Server) weblogic.application.ApplicationLifecycleListener. The container then searches for your listener.

You override the following methods provided in the WebLogic Server ApplicationLifecycleListener abstract class to extend your application and add any required functionality:

  • preStart{}

  • postStart{}

  • preStop{}

  • postStop{}

Example 13-1 illustrates how you override the ApplicationLifecycleListener. In this example, the public class MyListener extends ApplicationLifecycleListener.

Example 13-1 MyListener

import weblogic.application.ApplicationLifecycleListener;
import weblogic.application.ApplicationLifecycleEvent;
public class MyListener extends ApplicationLifecycleListener {
  public void preStart(ApplicationLifecycleEvent evt) {
     System.out.println
     ("MyListener(preStart) -- we should always see you..");
   } // preStart
  public void postStart(ApplicationLifecycleEvent evt) {
     System.out.println
     ("MyListener(postStart) -- we should always see you..");
   } // postStart
  public void preStop(ApplicationLifecycleEvent evt) {
     System.out.println
     ("MyListener(preStop) -- we should always see you..");
   } // preStop
  public void postStop(ApplicationLifecycleEvent evt) {
     System.out.println
     ("MyListener(postStop) -- we should always see you..");
   } // postStop
   public static void main(String[] args) {
     System.out.println
     ("MyListener(main): in main .. we should never see you..");
   } // main
}

Example 13-2 illustrates how you implement the shutdown class. The shutdown class is attachable to preStop and postStop events. In this example, the public class MyShutdown does not extend ApplicationLifecycleListener because a shutdown class declared in the weblogic-application.xml deployment descriptor does not need to depend on any WebLogic Server-specific interfaces.

Example 13-2 MyShutdown

import weblogic.application.ApplicationLifecycleListener;
import weblogic.application.ApplicationLifecycleEvent;
public class MyShutdown {
   public static void main(String[] args) {
     System.out.println
     ("MyShutdown(main): in main .. should be for post-stop");
   } // main
}

Example 13-3 illustrates how you implement the startup class. The startup class is attachable to preStart and postStart events. In this example, the public class MyStartup does not extend ApplicationLifecycleListener because a startup class declared in the weblogic-application.xml deployment descriptor does not need to depend on any WebLogic Server-specific interfaces.

Example 13-3 MyStartup

import weblogic.application.ApplicationLifecycleListener;
import weblogic.application.ApplicationLifecycleEvent;
public class MyStartup {
   public static void main(String[] args) {
     System.out.println
     ("MyStartup(main): in main .. should be for pre-start");
   } // main
}

Parent topic: Programming Application Life Cycle Events

Configuring a Role-Based Application Life Cycle Listener

You can configure an application life cycle event with role-based capability where a user identity can be specified to startup and shutdown events using the run-as-principal-name element. However, if the run-as-principal-name identity defined for the application life cycle listener is an administrator, the application deployer must have administrator privileges; otherwise, deployment will fail.

  1. Follow the basic programming steps outlined in Programming Basic Life Cycle Listener Functionality.
  2. Within the listener element add the run-as-principal-name element to specify the user who has privileges to startup and/or shutdown the event. For example:
    <listener>
  <listener-class>myApp.MySessionAttributeListenerClass</listener-class>
  <run-as-principal-name>javajoe</run-as-principal-name>
</listener>

The identity specified here should be a valid user name in the system. If run-as-principal-name is not specified, the deployment initiator user identity will be used as the run-as identity for the execution of the application life cycle listener.

Parent topic: Programming Basic Life Cycle Listener Functionality

Examples of Configuring Life Cycle Events with and without the URI Parameter

You can configure application life cycle events with or without using the URI parameter in the weblogic-application.xml deployment descriptor file.

The following examples illustrate how you configure application life cycle events in the weblogic-application.xml deployment descriptor file. The URI parameter is not required. You can place classes anywhere in the application $CLASSPATH. However, you must ensure that the class locations are defined in the $CLASSPATH. You can place listeners in APP-INF/classes or APP-INF/lib, if these directories are present in the EAR. In this case, they are automatically included in the $CLASSPATH.

The following example illustrates how you configure application life cycle events using the URI parameter. In this case, the archive foo.jar contains the classes and exists at the top level of the EAR file. For example: myEar/foo.jar.

Example 13-4 Configuring Application Life Cycle Events Using the URI Parameter

<listener>
     <listener-class>MyListener</listener-class>
     <listener-uri>foo.jar</listener-uri>
</listener>
<startup>
     <startup-class>MyStartup</startup-class>
     <startup-uri>foo.jar</startup-uri>
</startup>
<shutdown>
     <shutdown-class>MyShutdown</shutdown-class>
     <shutdown-uri>foo.jar</shutdown-uri>
</shutdown>

The following example illustrates how you configure application life cycle events without using the URI parameter.

Example 13-5 Configuring Application Life Cycle Events without Using the URI Parameter

<listener>
      <listener-class>MyListener</listener-class>
 </listener>
 <startup>
      <startup-class>MyStartup</startup-class>
 </startup>
 <shutdown>
      <shutdown-class>MyShutdown</shutdown-class>
 </shutdown>

Parent topic: Programming Application Life Cycle Events

Understanding Application Life Cycle Event Behavior During Redeployment

Application life cycle events are only triggered if a full redeployment of the application occurs. During a full redeployment of the application—provided the application life cycle events have been registered—the application life cycle first commences the shutdown sequence, next re-initializes its classes, and then performs the startup sequence.

For example, if your listener is registered for the full application life cycle set of events (preStart, postStart, preStop, postStop), during a full re-deployment, you see the following sequence of events:

  1. preStop{}

  2. postStop{}

  3. Initialization takes place. (Unless you have set debug flags, you do not see the initialization.)

  4. preStart{}

  5. postStart{}

Parent topic: Programming Application Life Cycle Events

Programming Application Version Life Cycle Events

Learn how to create applications that respond to WebLogic Server application version life cycle events.

Parent topic: Programming Application Life Cycle Events

Understanding Application Version Life Cycle Event Behavior

WebLogic Server provides application version life cycle event notifications by allowing you to extend the ApplicationVersionLifecycleListener class and specify a life cycle listener in weblogic-application.xml. See Enterprise Application Deployment Descriptor Elements and Examples of Configuring Life Cycle Events with and without the URI Parameter.

Application version life cycle events are invoked:

  • For both static and dynamic deployments.

  • Using either anonymous ID or using user identity.

  • Only if the current application is versioned; otherwise, version life cycle events are ignored.

  • For all application versions, including the version that registers the listener. Use the ApplicationVersionLifecycleEvent.isOwnVersion method to determine if an event belongs to a particular version. See the ApplicationVersionLifecycleEvent class for more information on types of version life cycle events.

Parent topic: Programming Application Version Life Cycle Events

Types of Application Version Life Cycle Events

Four application version life cycle events are provided with WebLogic Server:

Parent topic: Programming Application Version Life Cycle Events

Example of Production Deployment Sequence When Using Application Version Life Cycle Events

The following table provides an example of a deployment (V1), production redeployment (V2), and an undeploy (V2).

Table 13-1 Sequence of Deployment Actions and Application Version Life Cycle Events

Deployment action Time Version V1 Version V2

Deployment of Version V1

T0

preDeploy(V1) invoked.

Deployment of Version V1

T1

Deployment starts.

Deployment of Version V1

T2

Application life cycle listeners for V1 are registered.

Deployment of Version V1

T3

V1 is active version, Deployment is complete.

Deployment of Version V1

T4

postDeploy(V1) invoked.

Deployment of Version V1

T5

Application Listeners gets postDeploy(V1).

Production Redeployment of Version V2

T6

preDeploy(V2) invoked.

Production Redeployment of Version V2

T7

Application version listener receives preDeploy(V1).

Production Redeployment of Version V2

T8

Deployment starts.

Production Redeployment of Version V2

T9

Application life cycle listeners for V2 are registered.

Production Redeployment of Version V2

T10

If deploy(V2) succeeds, V1 ceases to be active version.

If deploy(V2) succeeds, V2 replaces V1 as active version.

Deployment is complete.

Production Redeployment of Version V2

T11

postDeploy(V2) invoked.

Note: This event occurs even if the deployment fails.

Production Redeployment of Version V2

T12

Application version listener gets postDeploy(V2). If deploy(V2) fails, V1 remains active.

Production Redeployment of Version V2

T13

Application listeners gets postDeploy(V2).

Production Redeployment of Version V2

T14

If deploy(V2) succeeds, V1 begins retirement.

Production Redeployment of Version V2

T15

Application listeners for V1 are unregistered.

Production Redeployment of Version V2

T16

V1 is retired.

Undeployment of V2

T17

preUndeploy(v2) invoked.

Undeployment of V2

T18

Application listeners gets preUndeploy(v2) invoked.

Undeployment of V2

T19

Undeployment begins.

Undeployment of V2

T20

V2 is no longer active version.

Undeployment of V2

T21

Application version listeners for V2 are unregistered.

Undeployment of V2

T22

Undeployment is complete.

Undeployment of V2

T23

If the entire application is undeployed, postDelete(V2) is invoked.

Note: This event occurs even if the undeployment fails.

Parent topic: Programming Application Version Life Cycle Events