Document Information


Part I Introduction

1.  Overview

2.  Using the Tutorial Examples

Part II The Web Tier

3.  Getting Started with Web Applications

4.  JavaServer Faces Technology

5.  Introduction to Facelets

6.  Expression Language

7.  Using JavaServer Faces Technology in Web Pages

8.  Using Converters, Listeners, and Validators

9.  Developing with JavaServer Faces Technology

10.  JavaServer Faces Technology: Advanced Concepts

11.  Using Ajax with JavaServer Faces Technology

12.  Composite Components: Advanced Topics and Example

13.  Creating Custom UI Components and Other Custom Objects

14.  Configuring JavaServer Faces Applications

15.  Java Servlet Technology

16.  Uploading Files with Java Servlet Technology

17.  Internationalizing and Localizing Web Applications

Part III Web Services

18.  Introduction to Web Services

19.  Building Web Services with JAX-WS

20.  Building RESTful Web Services with JAX-RS

21.  JAX-RS: Advanced Topics and Example

Part IV Enterprise Beans

22.  Enterprise Beans

23.  Getting Started with Enterprise Beans

24.  Running the Enterprise Bean Examples

25.  A Message-Driven Bean Example

26.  Using the Embedded Enterprise Bean Container

27.  Using Asynchronous Method Invocation in Session Beans

Part V Contexts and Dependency Injection for the Java EE Platform

28.  Introduction to Contexts and Dependency Injection for the Java EE Platform

29.  Running the Basic Contexts and Dependency Injection Examples

30.  Contexts and Dependency Injection for the Java EE Platform: Advanced Topics

Using Alternatives in CDI Applications

Using Specialization

Using Producer Methods, Producer Fields, and Disposer Methods in CDI Applications

Using Producer Methods

Using Producer Fields to Generate Resources

Using a Disposer Method

Using Predefined Beans in CDI Applications

Using Interceptors in CDI Applications

Using Decorators in CDI Applications

Using Stereotypes in CDI Applications

31.  Running the Advanced Contexts and Dependency Injection Examples

Part VI Persistence

32.  Introduction to the Java Persistence API

33.  Running the Persistence Examples

34.  The Java Persistence Query Language

35.  Using the Criteria API to Create Queries

36.  Creating and Using String-Based Criteria Queries

37.  Controlling Concurrent Access to Entity Data with Locking

38.  Using a Second-Level Cache with Java Persistence API Applications

Part VII Security

39.  Introduction to Security in the Java EE Platform

40.  Getting Started Securing Web Applications

41.  Getting Started Securing Enterprise Applications

42.  Java EE Security: Advanced Topics

Part VIII Java EE Supporting Technologies

43.  Introduction to Java EE Supporting Technologies

44.  Transactions

45.  Resources and Resource Adapters

46.  The Resource Adapter Example

47.  Java Message Service Concepts

48.  Java Message Service Examples

49.  Bean Validation: Advanced Topics

50.  Using Java EE Interceptors

Part IX Case Studies

51.  Duke's Bookstore Case Study Example

52.  Duke's Tutoring Case Study Example

53.  Duke's Forest Case Study Example



Using Events in CDI Applications

Events allow beans to communicate without any compile-time dependency. One bean can define an event, another bean can fire the event, and yet another bean can handle the event. The beans can be in separate packages and even in separate tiers of the application.

Defining Events

An event consists of the following:

  • The event object, a Java object

  • Zero or more qualifier types, the event qualifiers

For example, in the billpayment example described in The billpayment Example: Using Events and Interceptors, a PaymentEvent bean defines an event using three properties, which have setter and getter methods:

    public String paymentType;
    public BigDecimal value;
    public Date datetime;

    public PaymentEvent() {

The example also defines qualifiers that distinguish between two kinds of PaymentEvent. Every event also has the default qualifier @Any.

Using Observer Methods to Handle Events

An event handler uses an observer method to consume events.

Each observer method takes as a parameter an event of a specific event type that is annotated with the @Observes annotation and with any qualifiers for that event type. The observer method is notified of an event if the event object matches the event type and if all the qualifiers of the event match the observer method event qualifiers.

The observer method can take other parameters in addition to the event parameter. The additional parameters are injection points and can declare qualifiers.

The event handler for the billpayment example, PaymentHandler, defines two observer methods, one for each type of PaymentEvent:

public void creditPayment(@Observes @Credit PaymentEvent event) {

public void debitPayment(@Observes @Debit PaymentEvent event) {

Observer methods can also be conditional or transactional:

  • A conditional observer method is notified of an event only if an instance of the bean that defines the observer method already exists in the current context. To declare a conditional observer method, specify notifyObserver=IF_EXISTS as an argument to @Observes:


    To obtain the default unconditional behavior, you can specify @Observes(notifyObserver=ALWAYS).

  • A transactional observer method is notified of an event during the before-completion or after-completion phase of the transaction in which the event was fired. You can also specify that the notification is to occur only after the transaction has completed successfully or unsuccessfully. To specify a transactional observer method, use any of the following arguments to @Observes:


    To obtain the default non-transactional behavior, specify @Observes(during=IN_PROGRESS).

    An observer method that is called before completion of a transaction may call the setRollbackOnly method on the transaction instance to force a transaction rollback.

Observer methods may throw exceptions. If a transactional observer method throws an exception, the exception is caught by the container. If the observer method is non-transactional, the exception terminates processing of the event, and no other observer methods for the event are called.

Firing Events

To activate an event, call the method. This method fires an event and notifies any observer methods.

In the billpayment example, a managed bean called PaymentBean fires the appropriate event by using information it receives from the user interface. There are actually four event beans, two for the event object and two for the payload. The managed bean injects the two event beans. The pay method uses a switch statement to choose which event to fire, using new to create the payload.

    Event<PaymentEvent> creditEvent;

    Event<PaymentEvent> debitEvent;

    private static final int DEBIT = 1;
    private static final int CREDIT = 2;
    private int paymentOption = DEBIT;

    public String pay() {
        switch (paymentOption) {
            case DEBIT:
                PaymentEvent debitPayload = new PaymentEvent();
                // populate payload ... 
            case CREDIT:
                PaymentEvent creditPayload = new PaymentEvent();
                // populate payload ... 
                logger.severe("Invalid payment option!");

The argument to the fire method is a PaymentEvent that contains the payload. The fired event is then consumed by the observer methods.