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;
018
019 import java.util.List;
020 import java.util.Map;
021
022 import org.apache.camel.spi.Synchronization;
023 import org.apache.camel.spi.UnitOfWork;
024
025 /**
026 * An Exchange is the message container holding the information during the entire routing of
027 * a {@link Message} received by a {@link Consumer}.
028 * <p/>
029 * During processing down the {@link Processor} chain, the {@link Exchange} provides access to the
030 * current (not the original) request and response {@link Message} messages. The {@link Exchange}
031 * also holds meta-data during its entire lifetime stored as properties accessible using the
032 * various {@link #getProperty(String)} methods. The {@link #setProperty(String, Object)} is
033 * used to store a property. For example you can use this to store security, SLA related
034 * data or any other information deemed useful throughout processing. If an {@link Exchange}
035 * failed during routing the {@link Exception} that caused the failure is stored and accessible
036 * via the {@link #getException()} method.
037 * <p/>
038 * An Exchange is created when a {@link Consumer} receives a request. A new {@link Message} is
039 * created, the request is set as the body of the {@link Message} and depending on the {@link Consumer}
040 * other {@link Endpoint} and protocol related information is added as headers on the {@link Message}.
041 * Then an Exchange is created and the newly created {@link Message} is set as the in on the Exchange.
042 * Therefore an Exchange starts its life in a {@link Consumer}. The Exchange is then sent down the
043 * {@link Route} for processing along a {@link Processor} chain. The {@link Processor} as the name
044 * suggests is what processes the {@link Message} in the Exchange and Camel, in addition to
045 * providing out-of-the-box a large number of useful processors, it also allows you to create your own.
046 * The rule Camel uses is to take the out {@link Message} produced by the previous {@link Processor}
047 * and set it as the in for the next {@link Processor}. If the previous {@link Processor} did not
048 * produce an out, then the in of the previous {@link Processor} is sent as the next in. At the
049 * end of the processing chain, depending on the {@link ExchangePattern Message Exchange Pattern} (or MEP)
050 * the last out (or in of no out available) is sent by the {@link Consumer} back to the original caller.
051 * <p/>
052 * Camel, in addition to providing out-of-the-box a large number of useful processors, it also allows
053 * you to implement and use your own. When the Exchange is passed to a {@link Processor}, it always
054 * contains an in {@link Message} and no out {@link Message}. The {@link Processor} <b>may</b> produce
055 * an out, depending on the nature of the {@link Processor}. The in {@link Message} can be accessed
056 * using the {@link #getIn()} method. Since the out message is null when entering the {@link Processor},
057 * the {@link #getOut()} method is actually a convenient factory method that will lazily instantiate a
058 * {@link org.apache.camel.impl.DefaultMessage} which you could populate. As an alternative you could
059 * also instantiate your specialized {@link Message} and set it on the exchange using the
060 * {@link #setOut(org.apache.camel.Message)} method. Please note that a {@link Message} contains not only
061 * the body but also headers and attachments. If you are creating a new {@link Message} the headers and
062 * attachments of the in {@link Message} are not automatically copied to the out by Camel and you'll have
063 * to set the headers and attachments you need yourself. If your {@link Processor} is not producing a
064 * different {@link Message} but only needs to slightly modify the in, you can simply update the in
065 * {@link Message} returned by {@link #getIn()}.
066 * <p/>
067 * See this <a href="http://camel.apache.org/using-getin-or-getout-methods-on-exchange.html">FAQ entry</a>
068 * for more details.
069 *
070 */
071 public interface Exchange {
072
073 String AUTHENTICATION = "CamelAuthentication";
074 String AUTHENTICATION_FAILURE_POLICY_ID = "CamelAuthenticationFailurePolicyId";
075 String ACCEPT_CONTENT_TYPE = "CamelAcceptContentType";
076 String AGGREGATED_SIZE = "CamelAggregatedSize";
077 String AGGREGATED_COMPLETED_BY = "CamelAggregatedCompletedBy";
078 String AGGREGATED_CORRELATION_KEY = "CamelAggregatedCorrelationKey";
079 String AGGREGATION_STRATEGY = "CamelAggregationStrategy";
080 String ASYNC_WAIT = "CamelAsyncWait";
081
082 String BATCH_INDEX = "CamelBatchIndex";
083 String BATCH_SIZE = "CamelBatchSize";
084 String BATCH_COMPLETE = "CamelBatchComplete";
085 String BEAN_METHOD_NAME = "CamelBeanMethodName";
086 String BEAN_MULTI_PARAMETER_ARRAY = "CamelBeanMultiParameterArray";
087 String BINDING = "CamelBinding";
088
089 String CHARSET_NAME = "CamelCharsetName";
090 String CONTENT_ENCODING = "Content-Encoding";
091 String CONTENT_TYPE = "Content-Type";
092 String CORRELATION_ID = "CamelCorrelationId";
093
094 String DATASET_INDEX = "CamelDataSetIndex";
095 String DEFAULT_CHARSET_PROPERTY = "org.apache.camel.default.charset";
096 String DISABLE_HTTP_STREAM_CACHE = "CamelDisableHttpStreamCache";
097
098 String EXCEPTION_CAUGHT = "CamelExceptionCaught";
099 String ERRORHANDLER_HANDLED = "CamelErrorHandlerHandled";
100
101 String FAILURE_HANDLED = "CamelFailureHandled";
102 String FAILURE_ENDPOINT = "CamelFailureEndpoint";
103 String FILTER_NON_XML_CHARS = "CamelFilterNonXmlChars";
104 String FILE_LOCAL_WORK_PATH = "CamelFileLocalWorkPath";
105 String FILE_NAME = "CamelFileName";
106 String FILE_NAME_ONLY = "CamelFileNameOnly";
107 String FILE_NAME_PRODUCED = "CamelFileNameProduced";
108 String FILE_PATH = "CamelFilePath";
109 String FILE_PARENT = "CamelFileParent";
110 String FILE_LAST_MODIFIED = "CamelFileLastModified";
111 String FILTER_MATCHED = "CamelFilterMatched";
112
113 String GROUPED_EXCHANGE = "CamelGroupedExchange";
114
115 String HTTP_BASE_URI = "CamelHttpBaseUri";
116 String HTTP_CHARACTER_ENCODING = "CamelHttpCharacterEncoding";
117 String HTTP_METHOD = "CamelHttpMethod";
118 String HTTP_PATH = "CamelHttpPath";
119 String HTTP_PROTOCOL_VERSION = "CamelHttpProtocolVersion";
120 String HTTP_QUERY = "CamelHttpQuery";
121 String HTTP_RESPONSE_CODE = "CamelHttpResponseCode";
122 String HTTP_URI = "CamelHttpUri";
123 String HTTP_URL = "CamelHttpUrl";
124 String HTTP_CHUNKED = "CamelHttpChunked";
125 String HTTP_SERVLET_REQUEST = "CamelHttpServletRequest";
126 String HTTP_SERVLET_RESPONSE = "CamelHttpServletResponse";
127
128 String INTERCEPTED_ENDPOINT = "CamelInterceptedEndpoint";
129
130 String LANGUAGE_SCRIPT = "CamelLanguageScript";
131 String LOG_DEBUG_BODY_MAX_CHARS = "CamelLogDebugBodyMaxChars";
132 String LOG_DEBUG_BODY_STREAMS = "CamelLogDebugStreams";
133 String LOOP_INDEX = "CamelLoopIndex";
134 String LOOP_SIZE = "CamelLoopSize";
135
136 String MAXIMUM_CACHE_POOL_SIZE = "CamelMaximumCachePoolSize";
137 String MULTICAST_INDEX = "CamelMulticastIndex";
138 String MULTICAST_COMPLETE = "CamelMulticastComplete";
139
140 String NOTIFY_EVENT = "CamelNotifyEvent";
141
142 String ON_COMPLETION = "CamelOnCompletion";
143
144 String REDELIVERED = "CamelRedelivered";
145 String REDELIVERY_COUNTER = "CamelRedeliveryCounter";
146 String REDELIVERY_EXHAUSTED = "CamelRedeliveryExhausted";
147 String ROLLBACK_ONLY = "CamelRollbackOnly";
148 String ROLLBACK_ONLY_LAST = "CamelRollbackOnlyLast";
149 String ROUTE_STOP = "CamelRouteStop";
150
151 String SOAP_ACTION = "CamelSoapAction";
152 String SKIP_GZIP_ENCODING = "CamelSkipGzipEncoding";
153 String SLIP_ENDPOINT = "CamelSlipEndpoint";
154 String SPLIT_INDEX = "CamelSplitIndex";
155 String SPLIT_COMPLETE = "CamelSplitComplete";
156 String SPLIT_SIZE = "CamelSplitSize";
157
158 String TIMER_FIRED_TIME = "CamelTimerFiredTime";
159 String TIMER_NAME = "CamelTimerName";
160 String TIMER_PERIOD = "CamelTimerPeriod";
161 String TIMER_TIME = "CamelTimerTime";
162 String TO_ENDPOINT = "CamelToEndpoint";
163 String TRACE_EVENT = "CamelTraceEvent";
164 String TRACE_EVENT_NODE_ID = "CamelTraceEventNodeId";
165 String TRACE_EVENT_TIMESTAMP = "CamelTraceEventTimestamp";
166 String TRACE_EVENT_EXCHANGE = "CamelTraceEventExchange";
167 String TRANSFER_ENCODING = "Transfer-Encoding";
168
169 String XSLT_FILE_NAME = "CamelXsltFileName";
170
171 /**
172 * Returns the {@link ExchangePattern} (MEP) of this exchange.
173 *
174 * @return the message exchange pattern of this exchange
175 */
176 ExchangePattern getPattern();
177
178 /**
179 * Allows the {@link ExchangePattern} (MEP) of this exchange to be customized.
180 *
181 * This typically won't be required as an exchange can be created with a specific MEP
182 * by calling {@link Endpoint#createExchange(ExchangePattern)} but it is here just in case
183 * it is needed.
184 *
185 * @param pattern the pattern
186 */
187 void setPattern(ExchangePattern pattern);
188
189 /**
190 * Returns a property associated with this exchange by name
191 *
192 * @param name the name of the property
193 * @return the value of the given property or <tt>null</tt> if there is no property for
194 * the given name
195 */
196 Object getProperty(String name);
197
198 /**
199 * Returns a property associated with this exchange by name
200 *
201 * @param name the name of the property
202 * @param defaultValue the default value to return if property was absent
203 * @return the value of the given property or <tt>defaultValue</tt> if there is no
204 * property for the given name
205 */
206 Object getProperty(String name, Object defaultValue);
207
208 /**
209 * Returns a property associated with this exchange by name and specifying
210 * the type required
211 *
212 * @param name the name of the property
213 * @param type the type of the property
214 * @return the value of the given property or <tt>null</tt> if there is no property for
215 * the given name or <tt>null</tt> if it cannot be converted to the given type
216 */
217 <T> T getProperty(String name, Class<T> type);
218
219 /**
220 * Returns a property associated with this exchange by name and specifying
221 * the type required
222 *
223 * @param name the name of the property
224 * @param defaultValue the default value to return if property was absent
225 * @param type the type of the property
226 * @return the value of the given property or <tt>defaultValue</tt> if there is no property for
227 * the given name or <tt>null</tt> if it cannot be converted to the given type
228 */
229 <T> T getProperty(String name, Object defaultValue, Class<T> type);
230
231 /**
232 * Sets a property on the exchange
233 *
234 * @param name of the property
235 * @param value to associate with the name
236 */
237 void setProperty(String name, Object value);
238
239 /**
240 * Removes the given property on the exchange
241 *
242 * @param name of the property
243 * @return the old value of the property
244 */
245 Object removeProperty(String name);
246
247 /**
248 * Returns all of the properties associated with the exchange
249 *
250 * @return all the headers in a Map
251 */
252 Map<String, Object> getProperties();
253
254 /**
255 * Returns whether any properties has been set
256 *
257 * @return <tt>true</tt> if any properties has been set
258 */
259 boolean hasProperties();
260
261 /**
262 * Returns the inbound request message
263 *
264 * @return the message
265 */
266 Message getIn();
267
268 /**
269 * Returns the inbound request message as the given type
270 *
271 * @param type the given type
272 * @return the message as the given type or <tt>null</tt> if not possible to covert to given type
273 */
274 <T> T getIn(Class<T> type);
275
276 /**
277 * Sets the inbound message instance
278 *
279 * @param in the inbound message
280 */
281 void setIn(Message in);
282
283 /**
284 * Returns the outbound message, lazily creating one if one has not already
285 * been associated with this exchange.
286 * <p/>
287 * <br/><b>Important:</b> If you want to change the current message, then use {@link #getIn()} instead as it will
288 * ensure headers etc. is kept and propagated when routing continues. Bottom line end users should rarely use
289 * this method.
290 * <p/>
291 * <br/>If you want to test whether an OUT message have been set or not, use the {@link #hasOut()} method.
292 * <p/>
293 * See also the class java doc for this {@link Exchange} for more details and this
294 * <a href="http://camel.apache.org/using-getin-or-getout-methods-on-exchange.html">FAQ entry</a>.
295 *
296 * @return the response
297 * @see #getIn()
298 */
299 Message getOut();
300
301 /**
302 * Returns the outbound request message as the given type
303 * <p/>
304 * <br/><b>Important:</b> If you want to change the current message, then use {@link #getIn()} instead as it will
305 * ensure headers etc. is kept and propagated when routing continues. Bottom line end users should rarely use
306 * this method.
307 * <p/>
308 * <br/>If you want to test whether an OUT message have been set or not, use the {@link #hasOut()} method.
309 * <p/>
310 * See also the class java doc for this {@link Exchange} for more details and this
311 * <a href="http://camel.apache.org/using-getin-or-getout-methods-on-exchange.html">FAQ entry</a>.
312 *
313 * @param type the given type
314 * @return the message as the given type or <tt>null</tt> if not possible to covert to given type
315 * @see #getIn(Class)
316 */
317 <T> T getOut(Class<T> type);
318
319 /**
320 * Returns whether an OUT message has been set or not.
321 *
322 * @return <tt>true</tt> if an OUT message exists, <tt>false</tt> otherwise.
323 */
324 boolean hasOut();
325
326 /**
327 * Sets the outbound message
328 *
329 * @param out the outbound message
330 */
331 void setOut(Message out);
332
333 /**
334 * Returns the exception associated with this exchange
335 *
336 * @return the exception (or null if no faults)
337 */
338 Exception getException();
339
340 /**
341 * Returns the exception associated with this exchange.
342 * <p/>
343 * Is used to get the caused exception that typically have been wrapped in some sort
344 * of Camel wrapper exception
345 * <p/>
346 * The strategy is to look in the exception hierarchy to find the first given cause that matches the type.
347 * Will start from the bottom (the real cause) and walk upwards.
348 *
349 * @param type the exception type
350 * @return the exception (or <tt>null</tt> if no caused exception matched)
351 */
352 <T> T getException(Class<T> type);
353
354 /**
355 * Sets the exception associated with this exchange
356 * <p/>
357 * Camel will wrap {@link Throwable} into {@link Exception} type to
358 * accommodate for the {@link #getException()} method returning a plain {@link Exception} type.
359 *
360 * @param t the caused exception
361 */
362 void setException(Throwable t);
363
364 /**
365 * Returns true if this exchange failed due to either an exception or fault
366 *
367 * @return true if this exchange failed due to either an exception or fault
368 * @see Exchange#getException()
369 * @see Message#setFault(boolean)
370 * @see Message#isFault()
371 */
372 boolean isFailed();
373
374 /**
375 * Returns true if this exchange is transacted
376 */
377 boolean isTransacted();
378
379 /**
380 * Returns true if this exchange is marked for rollback
381 */
382 boolean isRollbackOnly();
383
384 /**
385 * Returns the container so that a processor can resolve endpoints from URIs
386 *
387 * @return the container which owns this exchange
388 */
389 CamelContext getContext();
390
391 /**
392 * Creates a copy of the current message exchange so that it can be
393 * forwarded to another destination
394 */
395 Exchange copy();
396
397 /**
398 * Returns the endpoint which originated this message exchange if a consumer on an endpoint
399 * created the message exchange, otherwise this property will be <tt>null</tt>
400 */
401 Endpoint getFromEndpoint();
402
403 /**
404 * Sets the endpoint which originated this message exchange. This method
405 * should typically only be called by {@link org.apache.camel.Endpoint} implementations
406 *
407 * @param fromEndpoint the endpoint which is originating this message exchange
408 */
409 void setFromEndpoint(Endpoint fromEndpoint);
410
411 /**
412 * Returns the route id which originated this message exchange if a route consumer on an endpoint
413 * created the message exchange, otherwise this property will be <tt>null</tt>
414 */
415 String getFromRouteId();
416
417 /**
418 * Sets the route id which originated this message exchange. This method
419 * should typically only be called by the internal framework.
420 *
421 * @param fromRouteId the from route id
422 */
423 void setFromRouteId(String fromRouteId);
424
425 /**
426 * Returns the unit of work that this exchange belongs to; which may map to
427 * zero, one or more physical transactions
428 */
429 UnitOfWork getUnitOfWork();
430
431 /**
432 * Sets the unit of work that this exchange belongs to; which may map to
433 * zero, one or more physical transactions
434 */
435 void setUnitOfWork(UnitOfWork unitOfWork);
436
437 /**
438 * Returns the exchange id (unique)
439 */
440 String getExchangeId();
441
442 /**
443 * Set the exchange id
444 */
445 void setExchangeId(String id);
446
447 /**
448 * Adds a {@link org.apache.camel.spi.Synchronization} to be invoked as callback when
449 * this exchange is completed.
450 *
451 * @param onCompletion the callback to invoke on completion of this exchange
452 */
453 void addOnCompletion(Synchronization onCompletion);
454
455 /**
456 * Handover all the on completions from this exchange to the target exchange.
457 *
458 * @param target the target exchange
459 */
460 void handoverCompletions(Exchange target);
461
462 /**
463 * Handover all the on completions from this exchange
464 *
465 * @return the on completions
466 */
467 List<Synchronization> handoverCompletions();
468
469 }