Enterprise JavaBeans 3.1 with Contexts and Dependency Injection: The Perfect Synergy - 0 views
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stateless EJB 3.1 bean as boundary (Facade)
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injected managed beans (controls)
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@Inject
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@Inject
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CDI managed beans. The @EJB annotation is removed and @Inject is used instead
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Annotating the boundary (Cart) with the @Named annotation makes the Cart immediately visible for expression language (EL) expressions in JSP and JSF
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@Named annotation takes the simple name of the annotated class, puts the first character in lowercase, and exposes it directly to the JSF pages (or JSP). The Cart bean can be accessed directly, without any backed or managed beans, by the JSF pages: <h:commandButton value="Check out!" action="#{cart.checkout}" />
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If there is a need for abstraction, the class can be turned into an interface (or abstract class)
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local implementation (with CDI events
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@Inject Event<String> event;
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event.fire("Order proceeded!");
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remote implementation:
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javax.enterprise.event.Event belongs to the CDI-implementation
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class Event can be considered to be a lightweight alternative to the java.beans.PropertyChangeSupport class
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@Inject Event<String> event;
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event.fire("Order proceeded!");
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event can be received by any managed bean and also by EJB beans
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provide a method with a single @Observes annotated parameter
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@Observes String event
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there is no real event, just the payload:
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The during attribute in the @Observes annotation allows you to select in which transactional phase the event gets delivered. The default setting is IN_PROGRESS, which causes an immediate event delivery regardless of the transaction outcome. The AFTER_SUCCESS configuration causes the delivery to occur only after successful transaction completion
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Although CDI events work only inside a single process (in the default case, CDI is extensible), they are perfectly suitable for decoupling packages from modules
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The method checkout() starts a transaction that gets "reused" by the OrderSystem and CustomerNotification session beans
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ordering.placeOrder(); notifier.sendNotification();
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EJB beans cannot be directly exposed to JSF or JSP without a little help from CDI