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APIs for CDI (Contexts and Dependency Injection for Java EE)
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/*
 * JBoss, Home of Professional Open Source
 * Copyright 2010, Red Hat, Inc., and individual contributors
 * by the @authors tag. See the copyright.txt in the distribution for a
 * full listing of individual contributors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * http://www.apache.org/licenses/LICENSE-2.0
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,  
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package javax.enterprise.event;

import java.lang.annotation.Annotation;

import javax.enterprise.util.TypeLiteral;

/**
 * 
 * Allows the application to fire events of a particular type.
 * 
 * 
 * 
 * Beans fire events via an instance of the Event interface, which may be injected:
 * 
 * 
 *  * @Inject
 * @Any
 * Event<LoggedInEvent> loggedInEvent;
 * 
 * 
 * 
 * The fire() method accepts an event object:
 * 
 * 
 *  * public void login() { 
 *    ...
 *    loggedInEvent.fire( new LoggedInEvent(user) );
 * }
 * 
 * 
 * 
 * Any combination of qualifiers may be specified at the injection point:
 * 
 * 
 *  * @Inject
 * @Admin
 * Event<LoggedInEvent> adminLoggedInEvent;
 * 
 * 
 * 
 * Or, the {@link javax.enterprise.inject.Any @Any} qualifier may be used, allowing the application to specify qualifiers
 * dynamically:
 * 
 * 
 *  * @Inject
 * @Any
 * Event<LoggedInEvent> loggedInEvent;
 * 
 * 
 * 
 * For an injected Event:
 * 
 * 
 * 
 * the specified type is the type parameter specified at the injection point, and
 * the specified qualifiers are the qualifiers specified at the injection point.
 * 
 * 
 * @author Gavin King
 * @author Pete Muir
 * @author David Allen
 * 
 * @param  the type of the event object
 */

public interface Event {

    /**
     * 
     * Fires an event with the specified qualifiers and notifies observers.
     * 
     * 
     * @param event the event object
     * @throws IllegalArgumentException if the runtime type of the event object contains a type variable
     * @throws ObserverException if a notified observer throws a checked exception, it will be wrapped and rethrown as an
     *         (unchecked) {@link ObserverException}
     */
    public void fire(T event);

    /**
     * 
     * Obtains a child Event for the given additional required qualifiers.
     * 
     * 
     * @param qualifiers the additional specified qualifiers
     * @return the child Event
     * @throws IllegalArgumentException if passed two instances of the same qualifier type, or an instance of an annotation that
     *         is not a qualifier type
     */
    public Event select(Annotation... qualifiers);

    /**
     * 
     * Obtains a child Event for the given required type and additional required qualifiers.
     * 
     * 
     * @param  the specified type
     * @param subtype a {@link java.lang.Class} representing the specified type
     * @param qualifiers the additional specified qualifiers
     * @return the child Event
     * @throws IllegalArgumentException if passed two instances of the same qualifier type, or an instance of an annotation that
     *         is not a qualifier type
     */
    public  Event select(Class subtype, Annotation... qualifiers);

    /**
     * 
     * Obtains a child Event for the given required type and additional required qualifiers.
     * 
     * 
     * @param  the specified type
     * @param subtype a {@link javax.enterprise.util.TypeLiteral} representing the specified type
     * @param qualifiers the additional specified qualifiers
     * @return the child Event
     * @throws IllegalArgumentException if passed two instances of the same qualifier type, or an instance of an annotation that
     *         is not a qualifier type
     */
    public  Event select(TypeLiteral subtype, Annotation... qualifiers);
}