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.camel.component.direct;
018    
019    import java.util.concurrent.CopyOnWriteArrayList;
020    
021    import org.apache.camel.Consumer;
022    import org.apache.camel.Exchange;
023    import org.apache.camel.Processor;
024    import org.apache.camel.Producer;
025    import org.apache.camel.impl.DefaultConsumer;
026    import org.apache.camel.impl.DefaultEndpoint;
027    import org.apache.camel.impl.DefaultExchange;
028    import org.apache.camel.impl.DefaultProducer;
029    import org.apache.commons.logging.Log;
030    import org.apache.commons.logging.LogFactory;
031    
032    /**
033     * Represents a direct endpoint that synchronously invokes the consumers of the
034     * endpoint when a producer sends a message to it.
035     * 
036     * @org.apache.xbean.XBean
037     * @version $Revision: 519973 $
038     */
039    public class DirectEndpoint<E extends Exchange> extends DefaultEndpoint<E> {
040        private static final Log LOG = LogFactory.getLog(DirectEndpoint.class);
041    
042        boolean allowMultipleConsumers = true;
043        private final CopyOnWriteArrayList<DefaultConsumer<E>> consumers = new CopyOnWriteArrayList<DefaultConsumer<E>>();
044    
045        public DirectEndpoint(String uri, DirectComponent<E> component) {
046            super(uri, component);
047        }
048    
049        public Producer createProducer() throws Exception {
050            return new DefaultProducer(this) {
051                public void process(Exchange exchange) throws Exception {
052                    DirectEndpoint.this.process(exchange);
053                }
054            };
055        }
056    
057        protected void process(Exchange exchange) throws Exception {
058            if (consumers.isEmpty()) {
059                LOG.warn("No consumers available on " + this + " for " + exchange);
060            } else {
061                for (DefaultConsumer<E> consumer : consumers) {
062                    consumer.getProcessor().process(exchange);
063                }
064            }
065        }
066    
067        public Consumer<E> createConsumer(Processor processor) throws Exception {
068            return new DefaultConsumer<E>(this, processor) {
069                @Override
070                public void start() throws Exception {
071                    if (!allowMultipleConsumers && !consumers.isEmpty()) {
072                        throw new IllegalStateException("Endpoint " + getEndpointUri() + " only allows 1 active consumer but you attempted to start a 2nd consumer.");
073                    }
074    
075                    consumers.add(this);
076                    super.start();
077                }
078    
079                @Override
080                public void stop() throws Exception {
081                    super.stop();
082                    consumers.remove(this);
083                }
084            };
085        }
086    
087        public E createExchange() {
088            // How can we create a specific Exchange if we are generic??
089            // perhaps it would be better if we did not implement this.
090            return (E)new DefaultExchange(getContext());
091        }
092    
093        public boolean isAllowMultipleConsumers() {
094            return allowMultipleConsumers;
095        }
096    
097        public void setAllowMultipleConsumers(boolean allowMutlipleConsumers) {
098            this.allowMultipleConsumers = allowMutlipleConsumers;
099        }
100    
101        public boolean isSingleton() {
102            return true;
103        }
104    
105    }