The following sections describe how to create applications that respond to WebLogic Server application life cycle events:
Examples of Configuring Life Cycle Events with and without the URI Parameter
Understanding Application Life Cycle Event Behavior During Re-deployment
Programming Application Version Life Cycle Events
Note: :
Application-scoped startup and shutdown classes have been deprecated as of release 9.0 of WebLogic Server. The information in this chapter about startup and shutdown classes is provided only for backwards compatibility. Instead, you should use life cycle listener events in your applications.Application life cycle listener events provide handles on which developers can control behavior during deployment, undeployment, and redeployment. This section discusses 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.
Notes:
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).
In order to use these events, you must register them in the weblogic-application.xml deployment descriptor. See Appendix A, "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.
You 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 10-1 illustrates how you override the ApplicationLifecycleListener. In this example, the public class MyListener extends ApplicationLifecycleListener.
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 10-2 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.
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 10-3 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.
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
}
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.
Follow the basic programming steps outlined in Programming Basic Life Cycle Listener Functionality.
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.
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 10-4 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.
Application life cycle events are only triggered if a full re-deployment of the application occurs. During a full re-deployment 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:
preStop{}
postStop{}
Initialization takes place. (Unless you have set debug flags, you do not see the initialization.)
preStart{}
postStart{}
The following sections describe how to create applications that respond to WebLogic Server application version life cycle events:
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 Appendix A, "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.
Four application version life cycle events are provided with WebLogic Server:
public void preDeploy(ApplicationVersionLifecycleEvent evt)
The preDeloy event is invoked when an application version deploy or redeploy operation is initiated.
public void postDeploy(ApplicationVersionLifecycleEvent evt)
The postDeloy event is invoked when an application version is deployed or redeployed successfully.
public void preUndeploy(ApplicationVersionLifecycleEvent evt)
The preUndeloy event is invoked when an application version undeploy operation is initiated.
public void postDelete(ApplicationVersionLifecycleEvent evt)
The postDelete event is invoked when an application version is deleted.
Note:
ApostDelete event is only fired after the entire application version is completely removed. It does not include a partial undeploy, such as undeploying a module or from a subset of targets.The following table provides an example of a deployment (V1), production redeployment (V2), and an undeploy (V2).
Table 10-1 Sequence of Deployment Actions and Application Version Life Cycle Events
| Deployment action | Time | Version V1 | Version V2 |
|---|---|---|---|
|
Deployment of Version V1 |
T0 |
|
|
|
T1 |
Deployment starts. |
||
|
T2 |
Application life cycle listeners for V1 are registered. |
||
|
T3 |
V1 is active version, Deployment is complete. |
||
|
T4 |
|
||
|
T5 |
Application Listeners gets |
||
|
Production Redeployment of Version V2 |
T6 |
|
|
|
T7 |
Application version listener receives |
||
|
T8 |
Deployment starts. |
||
|
T9 |
Application life cycle listeners for V2 are registered. |
||
|
T10 |
If deploy(V2) succeeds, V1 ceases to be active version. |
If deploy(V2) succeeds, V2 replaces V1 as active version. Deployment is complete. |
|
|
T11 |
Note: This event occurs even if the deployment fails. |
||
|
T12 |
Application version listener gets |
||
|
T13 |
Application listeners gets |
||
|
T14 |
If deploy(V2) succeeds, V1 begins retirement. |
||
|
T15 |
Application listeners for V1 are unregistered. |
||
|
T16 |
V1 is retired. |
||
|
Undeployment of V2 |
T17 |
|
|
|
T18 |
Application listeners gets |
||
|
T19 |
Undeployment begins. |
||
|
T20 |
V2 is no longer active version. |
||
|
T21 |
Application version listeners for V2 are unregistered. |
||
|
T22 |
Undeployment is complete. |
||
|
T23 |
If the entire application is undeployed, Note: This event occurs even if the undeployment fails. |