/*
 * JBoss, Home of Professional Open Source
 * Copyright 2009 Red Hat Inc. and/or its affiliates and other
 * contributors as indicated by the @author tags. All rights reserved.
 * See the copyright.txt in the distribution for a full listing of
 * individual contributors.
 *
 * This is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation; either version 2.1 of
 * the License, or (at your option) any later version.
 *
 * This software is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this software; if not, write to the Free
 * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
 */
package org.infinispan.notifications;

import java.util.Set;

/**
 * Interface that denotes that the implementation can have listeners attached to it.
 *
 * @author Manik Surtani
 * @since 4.0
 */
public interface Listenable {

   /**
    * Adds a listener to the component.  Typically, listeners would need to be annotated with {@link Listener} and
    * further to that, contain methods annotated appropriately, otherwise the listener will not be registered.
    * <p/>
    * See the {@link Listener} annotation for more information.
    * <p/>
    *
    * @param listener must not be null.
    */
   void addListener(Object listener);

   /**
    * Removes a listener from the component.
    *
    * @param listener listener to remove.  Must not be null.
    */
   void removeListener(Object listener);

   /**
    * @return a set of all listeners registered on this component.
    */
   Set<Object> getListeners();
}
