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.servicemix.jbi.nmr.flow.st;
018    
019    import javax.jbi.messaging.MessageExchange;
020    import javax.jbi.messaging.MessagingException;
021    
022    import org.apache.servicemix.jbi.messaging.MessageExchangeImpl;
023    import org.apache.servicemix.jbi.nmr.flow.AbstractFlow;
024    import org.apache.servicemix.jbi.servicedesc.AbstractServiceEndpoint;
025    
026    /**
027     * A simple Straight through flow.
028     * 
029     * A MessageExchange is routed straight to it's destination with 
030     * no staging or buffering. A straight through flow is best suited 
031     * for the cases where the ServiceMix JBIContainer is deployed with simple 
032     * flows (no state) or embedding, or where latency needs to be as low as possible.
033     * 
034     * @version $Revision: 564607 $
035     * @org.apache.xbean.XBean element="stFlow"
036     */
037    public class STFlow extends AbstractFlow {
038        
039        /**
040         * Distribute an ExchangePacket
041         * 
042         * @param packet
043         * @throws MessagingException
044         */
045        protected void doSend(MessageExchangeImpl me) throws MessagingException {
046            if (me.getDestinationId() == null) {
047                me.setDestinationId(((AbstractServiceEndpoint) me.getEndpoint()).getComponentNameSpace());
048            }
049            doRouting(me);
050        }
051        
052        /**
053         * The type of Flow
054         * @return the type
055         */
056        public String getDescription() {
057            return "st";
058        }
059        
060        /**
061         * Check if the flow can support the requested QoS for this exchange
062         * @param me the exchange to check
063         * @return true if this flow can handle the given exchange
064         */
065        public boolean canHandle(MessageExchange me) {
066            if (isPersistent(me)) {
067                return false;
068            }
069            if (isClustered(me)) {
070                return false;
071            }
072            // We can not handle transactional exchanges:
073            //  * asynchronous is a bit weird when the transaction is conveyed
074            //  * synchronous could lead to deadlock if the provider uses Push delivery
075            if (isTransacted(me)) {
076                return false;
077            }
078            return true;
079        }
080        
081    }