/*
* JBoss, Home of Professional Open Source
* Copyright 2008, Red Hat Middleware LLC, 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 static java.lang.annotation.ElementType.PARAMETER;
import static java.lang.annotation.RetentionPolicy.RUNTIME;

import java.lang.annotation.Documented;
import java.lang.annotation.Retention;
import java.lang.annotation.Target;

/**
 * <p>Identifies the event parameter of an observer method. May be applied to 
 * a parameter of a method of a bean class or 
 * {@linkplain javax.enterprise.inject.spi.Extension extension}.</p>
 * 
 * <pre>
 * public void afterLogin(&#064;Observes LoggedInEvent event) { ... }
 * </pre>
 * 
 * <p>An observer method is a non-abstract method of a managed bean class or 
 * session bean class (or of an extension). An observer method may be either 
 * static or non-static. If the bean is a session bean, the observer method 
 * must be either a business method of the EJB or a static method of the bean 
 * class.</p>
 * 
 * <p>Each observer method must have exactly one event parameter, of the same 
 * type as the event type it observes. Event qualifiers may be declared 
 * by annotating the event parameter. When searching for observer methods for 
 * an event, the container considers the type and qualifiers of the event 
 * parameter.</p>
 * 
 * <p>If the event parameter does not explicitly declare any qualifier, the 
 * observer method observes events with no qualifier.</p> 
 * 
 * <p>The event parameter type may contain a type variable or wildcard.</p>
 * 
 * <p>A bean (or extension) may declare multiple observer methods.</p>
 * 
 * <p>Observer methods are inherited by bean subclasses.</p>
 * 
 * <p>Interceptors and decorators may not declare observer 
 * methods.</p>
 * 
 * @author Gavin King
 * @author Pete Muir
 * @author David Allen
 */

@Target(PARAMETER)
@Retention(RUNTIME)
@Documented
public @interface Observes
{
   /**
    * <p>Specifies 
    * {@linkplain javax.enterprise.event.Reception under what conditions the 
    * observer method is notified}.</p>
    * 
    * <p>By default, the observer method is notified even if no instance of
    * the bean that defines the observer method already exists in the current 
    * context.</p>
    */
	public Reception notifyObserver() default Reception.ALWAYS;
	
	/**
	 * <p>Specifies 
	 * {@linkplain javax.enterprise.event.Reception at what time the observer
	 * method is notified}.</p>
	 * 
	 * <p>By default, the observer method is notified when the event is fired.</p>
	 */
	public TransactionPhase during() default TransactionPhase.IN_PROGRESS;
}
