Chapter 10. Weld-OSGi events

10.1. CDI container lifecycle events
10.2. Bundle lifecycle events
10.3. Service lifecyle events
10.4. Bean bundle required service dependency validation events
10.5. Intra and inter bundles communication events

Weld-OSGi provides numerous events about OSGi events and bean bundle lifecycle events. It also allows decoupled bean bundle communication.

All these features uses CDI events mechanisms:

These events may be listened with a Observes annotated parameter method
```
public void bindBundle(@Observes AbstractBundleEvent event) {
}
```

These events may be fired with the regular CDI mechanisms

BeanManager beanManager;
...
beanManager.fireEvent(new BundleContainerEvents.BundleContainerInitialized(bundle.getBundleContext()));

Event<Object> event;
...
event.select(AbstractBundleEvent.class).fire(new BundleInstalled(bundle));

10.1. CDI container lifecycle events

Weld-OSGi provides a CDI event notification for bean bundle about bean bundle CDI container lifecycle events:

A BundleContainerInitialized event is fired every time a bean bundle CDI container is initialized
A BundleContainerShutdown event is fired every time a bean bundle CDI container is shutdown

10.2. Bundle lifecycle events

Weld-OSGi provides a CDI event notification for bean bundle about bundle lifecycle events:

Such an event is fired every time the correspondent OSGi bundle event is fired
All bundle lifecycle events may be listened using the AbstractBundleEvent event
Specific bundle lifecycle events are: BundleInstalled, BundleUninstalled, BundleLazyActivation, BundleResolved, BundleUnresolved, BundleUpdated, BundleStarted, BundleStarting, BundleStopped and BundleStopping

It is possible to filter the listened source bundle by bundle symbolic name and version (optional)

public void bindBundle(@Observes @BundleName("com.sample.gui") @BundleVersion("4.2.1") AbstractBundleEvent event) {
}
public void bindBundle(@Observes @BundleName("com.sample.gui") BundleInstalled event) {
}

Only the events from the corresponding bundle are listened.

If a BundleVersion annotation is provided without a BundleName annotation Weld-OSGi detects the problem and treats it as an error.

10.3. Service lifecyle events

Weld-OSGi provides a CDI event notification for bean bundle about service lifecycle events:

Such an event is fired every time the correspondent OSGi service event is fired
All service lifecycle events may be listen using the AbstractServiceEvent event
Specific bundle lifecycle events are: ServiceArrival, ServiceDeparture and ServiceChanged

It is possible to filter the listened source service by specification and or OSGi LDAP properties and filter

public void bindService(@Observes @Specification(MyService.class) AbstractServiceEvent event) {
}
public void bindService(@Observes @AnyQualifier ServiceArrival event) {
}
public void bindService(@Observes @Specification(MyService.class) @Filter("(&(lang=EN)(country=US))") ServiceChanged event) {
}

Only the corresponding service events are listened.

10.4. Bean bundle required service dependency validation events

Weld-OSGi provides a CDI event notification for bean bundle about bean bundle required service dependency validation:

A Valid event is fired every time a bean bundle got all its required service dependency validated
A Invalid event is fired every time a bean bundle got one of its required service dependency invalidated

10.5. Intra and inter bundles communication events

Weld-OSGi provides a way to communicate within and between bean bundles:

A InterBundleEvent is fired by a bean bundle

@Inject Event<InterBundleEvent> event;
MyMessage myMessage = new MyMessage();
event.fire(new InterBundleEvent(myMessage));

A InterBundleEvent may be listened by every active bean bundle

It is possible to filter the listened source message by message type and ignoring the events from the current bundle

public void listenAllEventsFromOtherBundles(@Observes @Sent InterBundleEvent event) {
}
public void listenMyMessageEvents(@Observes @Specification(MyMessage.class) InterBundleEvent event) {
}
public void listenMyMessageEventsFromOtherBundles(@Observes @Sent @Specification(MyMessage.class) InterBundleEvent event) {
}

Only the corresponding events are listened.