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 */
017package org.apache.activemq.broker.region.policy;
018
019import java.util.List;
020
021import org.apache.activemq.broker.region.MessageReference;
022import org.apache.activemq.broker.region.Subscription;
023import 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 */
032public 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}