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payment-cdi-event: Use CDI Events to Process Debit and Credit Operations

The payment-cdi-event quickstart demonstrates how to create credit and debit CDI Events in WildFly, using a JSF front-end client.

What is it?

The payment-cdi-event quickstart demonstrates how to use CDI Events in WildFly Application Server.

The JSF front-end client allows you to create both credit and debit operation events.

To test this quickstart, enter an amount, choose either a Credit or Debit operation, and then click on Pay to create the event.

A Session scoped (@SessionScoped) payment event handler catches the operation and produces (@Produces) a named list of all operations performed during this session. The event is logged in the WildFly server log and the event list is displayed in a table at the bottom of the form.

The payment-cdi-event quickstart defines the following classes and interfaces:

  • The beans package contains the PaymentBean bean class:

  • This is a session scoped bean that stores the payment form information:

    • payment amount

    • operation type: debit or credit

  • It contains the following utility methods:

    • private void init(): This is a PostConstruct (@PostConstruct) method that performs initialization before the class is put into service. It resets the amount to $0 and the paymentOption to the default type of debit.

    • public String pay(): This method processes the operation when the user clicks on submit. We have only one JSF page, so the method does not return anything and the flow of control does not change.

    • public void reset(): Reset calls the init() method reinitialize the form values.

  • The events package contains the PaymentEvent class and the enum PaymentTypeEnum.

  • PaymentEvent: We have only one event that handles both credit and debit operations. Qualifiers help us to make the difference at injection point.

  • PaymentTypeEnum: A typesafe enum is used to represent the operation payment type. It contains utility methods to convert between String and Enum.

  • The qualifiers package contains the Credit and Debit interfaces. The annotation determines the operation of the injecting Event.

  • The handler package contains interfaces and implementations of PaymentEvent observers.

  • ICreditEventObserver: Interface to listen to CREDIT event only (@Observes @Credit).

  • IDebitEventObserver: Interface to listen to DEBIT event (@Observes @Debit).

  • PaymentHandler: The concrete implementation of the payment handler.

    • It implements both ICreditEventObserver and IDebitEventObserver.

    • The payment handler exposes the list of events caught during a session (@Named name=payments).

  • The resources package contains the Resources class that produces the logger for the application.