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.processor; 018 019 import java.util.Collection; 020 import java.util.Iterator; 021 import java.util.List; 022 023 import org.apache.camel.AsyncCallback; 024 import org.apache.camel.AsyncProcessor; 025 import org.apache.camel.CamelContext; 026 import org.apache.camel.Exchange; 027 import org.apache.camel.Processor; 028 import org.apache.camel.Traceable; 029 import org.apache.camel.util.AsyncProcessorConverterHelper; 030 import org.apache.camel.util.AsyncProcessorHelper; 031 import org.apache.camel.util.ExchangeHelper; 032 import org.slf4j.Logger; 033 import org.slf4j.LoggerFactory; 034 035 import static org.apache.camel.processor.PipelineHelper.continueProcessing; 036 037 /** 038 * Creates a Pipeline pattern where the output of the previous step is sent as 039 * input to the next step, reusing the same message exchanges 040 * 041 * @version 042 */ 043 public class Pipeline extends MulticastProcessor implements AsyncProcessor, Traceable { 044 private static final transient Logger LOG = LoggerFactory.getLogger(Pipeline.class); 045 046 public Pipeline(CamelContext camelContext, Collection<Processor> processors) { 047 super(camelContext, processors); 048 } 049 050 public static Processor newInstance(CamelContext camelContext, List<Processor> processors) { 051 if (processors.isEmpty()) { 052 return null; 053 } else if (processors.size() == 1) { 054 return processors.get(0); 055 } 056 return new Pipeline(camelContext, processors); 057 } 058 059 public void process(Exchange exchange) throws Exception { 060 AsyncProcessorHelper.process(this, exchange); 061 } 062 063 public boolean process(Exchange exchange, AsyncCallback callback) { 064 Iterator<Processor> processors = getProcessors().iterator(); 065 Exchange nextExchange = exchange; 066 boolean first = true; 067 068 while (continueRouting(processors, nextExchange)) { 069 if (first) { 070 first = false; 071 } else { 072 // prepare for next run 073 nextExchange = createNextExchange(nextExchange); 074 } 075 076 // get the next processor 077 Processor processor = processors.next(); 078 079 AsyncProcessor async = AsyncProcessorConverterHelper.convert(processor); 080 boolean sync = process(exchange, nextExchange, callback, processors, async); 081 082 // continue as long its being processed synchronously 083 if (!sync) { 084 LOG.trace("Processing exchangeId: {} is continued being processed asynchronously", exchange.getExchangeId()); 085 // the remainder of the pipeline will be completed async 086 // so we break out now, then the callback will be invoked which then continue routing from where we left here 087 return false; 088 } 089 090 LOG.trace("Processing exchangeId: {} is continued being processed synchronously", exchange.getExchangeId()); 091 092 // check for error if so we should break out 093 if (!continueProcessing(nextExchange, "so breaking out of pipeline", LOG)) { 094 break; 095 } 096 } 097 098 // logging nextExchange as it contains the exchange that might have altered the payload and since 099 // we are logging the completion if will be confusing if we log the original instead 100 // we could also consider logging the original and the nextExchange then we have *before* and *after* snapshots 101 LOG.trace("Processing complete for exchangeId: {} >>> {}", exchange.getExchangeId(), nextExchange); 102 103 // copy results back to the original exchange 104 ExchangeHelper.copyResults(exchange, nextExchange); 105 106 callback.done(true); 107 return true; 108 } 109 110 private boolean process(final Exchange original, final Exchange exchange, final AsyncCallback callback, 111 final Iterator<Processor> processors, final AsyncProcessor asyncProcessor) { 112 // this does the actual processing so log at trace level 113 LOG.trace("Processing exchangeId: {} >>> {}", exchange.getExchangeId(), exchange); 114 115 // implement asynchronous routing logic in callback so we can have the callback being 116 // triggered and then continue routing where we left 117 boolean sync = AsyncProcessorHelper.process(asyncProcessor, exchange, new AsyncCallback() { 118 public void done(boolean doneSync) { 119 // we only have to handle async completion of the pipeline 120 if (doneSync) { 121 return; 122 } 123 124 // continue processing the pipeline asynchronously 125 Exchange nextExchange = exchange; 126 while (continueRouting(processors, nextExchange)) { 127 AsyncProcessor processor = AsyncProcessorConverterHelper.convert(processors.next()); 128 129 // check for error if so we should break out 130 if (!continueProcessing(nextExchange, "so breaking out of pipeline", LOG)) { 131 break; 132 } 133 134 nextExchange = createNextExchange(nextExchange); 135 doneSync = process(original, nextExchange, callback, processors, processor); 136 if (!doneSync) { 137 LOG.trace("Processing exchangeId: {} is continued being processed asynchronously", exchange.getExchangeId()); 138 return; 139 } 140 } 141 142 ExchangeHelper.copyResults(original, nextExchange); 143 LOG.trace("Processing complete for exchangeId: {} >>> {}", original.getExchangeId(), original); 144 callback.done(false); 145 } 146 }); 147 148 return sync; 149 } 150 151 /** 152 * Strategy method to create the next exchange from the previous exchange. 153 * <p/> 154 * Remember to copy the original exchange id otherwise correlation of ids in the log is a problem 155 * 156 * @param previousExchange the previous exchange 157 * @return a new exchange 158 */ 159 protected Exchange createNextExchange(Exchange previousExchange) { 160 Exchange answer = previousExchange; 161 162 // now lets set the input of the next exchange to the output of the 163 // previous message if it is not null 164 if (answer.hasOut()) { 165 answer.setIn(answer.getOut()); 166 answer.setOut(null); 167 } 168 return answer; 169 } 170 171 protected boolean continueRouting(Iterator<Processor> it, Exchange exchange) { 172 boolean answer = true; 173 174 Object stop = exchange.getProperty(Exchange.ROUTE_STOP); 175 if (stop != null) { 176 boolean doStop = exchange.getContext().getTypeConverter().convertTo(Boolean.class, stop); 177 if (doStop) { 178 LOG.debug("ExchangeId: {} is marked to stop routing: {}", exchange.getExchangeId(), exchange); 179 answer = false; 180 } 181 } else { 182 // continue if there are more processors to route 183 answer = it.hasNext(); 184 } 185 186 LOG.trace("ExchangeId: {} should continue routing: {}", exchange.getExchangeId(), answer); 187 return answer; 188 } 189 190 @Override 191 public String toString() { 192 return "Pipeline[" + getProcessors() + "]"; 193 } 194 195 @Override 196 public String getTraceLabel() { 197 return "pipeline"; 198 } 199 }