001    /**
002     * Licensed to the Apache Software Foundation (ASF) under one or more
003     * contributor license agreements.  See the NOTICE file distributed with
004     * this work for additional information regarding copyright ownership.
005     * The ASF licenses this file to You under the Apache License, Version 2.0
006     * (the "License"); you may not use this file except in compliance with
007     * the License.  You may obtain a copy of the License at
008     *
009     *      http://www.apache.org/licenses/LICENSE-2.0
010     *
011     * Unless required by applicable law or agreed to in writing, software
012     * distributed under the License is distributed on an "AS IS" BASIS,
013     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014     * See the License for the specific language governing permissions and
015     * limitations under the License.
016     */
017    package org.apache.activemq.broker.region.policy;
018    
019    import java.util.List;
020    
021    import org.apache.activemq.broker.region.MessageReference;
022    import org.apache.activemq.broker.region.Subscription;
023    import org.apache.activemq.filter.MessageEvaluationContext;
024    
025    /**
026     * Abstraction to allow different dispatching policies to be plugged
027     * into the  topic region implementations.  This is used by a topic to deliver
028     * messages to the matching subscriptions.
029     * 
030     * 
031     */
032    public interface DispatchPolicy {
033        
034        /**
035         * Decides how to dispatch a selected message to a collection of consumers.  A safe
036         * approach is to dispatch to every subscription that matches.
037         *
038         * The list will be safe to iterate over when this method is called
039         * 
040         * @return true if at least one consumer was dispatched or false if there are no active subscriptions that could be dispatched
041         */
042        boolean dispatch(MessageReference node, MessageEvaluationContext msgContext, List<Subscription> consumers) throws Exception;
043    
044    }