Veto.java

/*
 * Copyright (c) 2009, Paul Merlin. All Rights Reserved.
 *
 * 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 org.swing.on.steroids.messagebus;

/**
 * @author Paul Merlin 
 */
public interface Veto
{

    /**
     * Determine whether a Message should be vetoed or published.
     *
     * All MessageBus implementations call this method before Message delivery. If any of the Veto
     * return true, then none of the Subscribers for that MessageType are called.
     *
     * @param <S>       Subscriber mark type, for type safety
     * @param message   Message
     * @return          True if the Message has to be vetoed, false otherwise.
     */
    <S extends Subscriber> boolean veto( Message<S> message );

}