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_TIMEOUT = "CamelAggregatedTimeout";
078 String AGGREGATED_COMPLETED_BY = "CamelAggregatedCompletedBy";
079 String AGGREGATED_CORRELATION_KEY = "CamelAggregatedCorrelationKey";
080 String AGGREGATION_STRATEGY = "CamelAggregationStrategy";
081 String AGGREGATION_COMPLETE_ALL_GROUPS = "CamelAggregationCompleteAllGroups";
082 String AGGREGATION_COMPLETE_ALL_GROUPS_INCLUSIVE = "CamelAggregationCompleteAllGroupsInclusive";
083 String ASYNC_WAIT = "CamelAsyncWait";
084
085 String BATCH_INDEX = "CamelBatchIndex";
086 String BATCH_SIZE = "CamelBatchSize";
087 String BATCH_COMPLETE = "CamelBatchComplete";
088 String BEAN_METHOD_NAME = "CamelBeanMethodName";
089 String BEAN_MULTI_PARAMETER_ARRAY = "CamelBeanMultiParameterArray";
090 String BINDING = "CamelBinding";
091 // do not prefix with Camel and use lower-case starting letter as its a shared key
092 // used across other Apache products such as AMQ, SMX etc.
093 String BREADCRUMB_ID = "breadcrumbId";
094
095 String CHARSET_NAME = "CamelCharsetName";
096 String CREATED_TIMESTAMP = "CamelCreatedTimestamp";
097 String CONTENT_ENCODING = "Content-Encoding";
098 String CONTENT_LENGTH = "Content-Length";
099 String CONTENT_TYPE = "Content-Type";
100 String CORRELATION_ID = "CamelCorrelationId";
101
102 String DATASET_INDEX = "CamelDataSetIndex";
103 String DEFAULT_CHARSET_PROPERTY = "org.apache.camel.default.charset";
104 String DESTINATION_OVERRIDE_URL = "CamelDestinationOverrideUrl";
105 String DISABLE_HTTP_STREAM_CACHE = "CamelDisableHttpStreamCache";
106 String DUPLICATE_MESSAGE = "CamelDuplicateMessage";
107
108 String EXCEPTION_CAUGHT = "CamelExceptionCaught";
109 String EXCEPTION_HANDLED = "CamelExceptionHandled";
110 String EVALUATE_EXPRESSION_RESULT = "CamelEvaluateExpressionResult";
111 String ERRORHANDLER_HANDLED = "CamelErrorHandlerHandled";
112 String EXTERNAL_REDELIVERED = "CamelExternalRedelivered";
113
114 String FAILURE_HANDLED = "CamelFailureHandled";
115 String FAILURE_ENDPOINT = "CamelFailureEndpoint";
116 String FAILURE_ROUTE_ID = "CamelFailureRouteId";
117 String FILTER_NON_XML_CHARS = "CamelFilterNonXmlChars";
118 String FILE_LOCAL_WORK_PATH = "CamelFileLocalWorkPath";
119 String FILE_NAME = "CamelFileName";
120 String FILE_NAME_ONLY = "CamelFileNameOnly";
121 String FILE_NAME_PRODUCED = "CamelFileNameProduced";
122 String FILE_NAME_CONSUMED = "CamelFileNameConsumed";
123 String FILE_PATH = "CamelFilePath";
124 String FILE_PARENT = "CamelFileParent";
125 String FILE_LAST_MODIFIED = "CamelFileLastModified";
126 String FILE_LENGTH = "CamelFileLength";
127 String FILTER_MATCHED = "CamelFilterMatched";
128 String FILE_LOCK_FILE_ACQUIRED = "CamelFileLockFileAcquired";
129 String FILE_LOCK_FILE_NAME = "CamelFileLockFileName";
130
131 String GROUPED_EXCHANGE = "CamelGroupedExchange";
132
133 String HTTP_BASE_URI = "CamelHttpBaseUri";
134 String HTTP_CHARACTER_ENCODING = "CamelHttpCharacterEncoding";
135 String HTTP_METHOD = "CamelHttpMethod";
136 String HTTP_PATH = "CamelHttpPath";
137 String HTTP_PROTOCOL_VERSION = "CamelHttpProtocolVersion";
138 String HTTP_QUERY = "CamelHttpQuery";
139 String HTTP_RESPONSE_CODE = "CamelHttpResponseCode";
140 String HTTP_URI = "CamelHttpUri";
141 String HTTP_URL = "CamelHttpUrl";
142 String HTTP_CHUNKED = "CamelHttpChunked";
143 String HTTP_SERVLET_REQUEST = "CamelHttpServletRequest";
144 String HTTP_SERVLET_RESPONSE = "CamelHttpServletResponse";
145
146 String INTERCEPTED_ENDPOINT = "CamelInterceptedEndpoint";
147 String INTERCEPT_SEND_TO_ENDPOINT_WHEN_MATCHED = "CamelInterceptSendToEndpointWhenMatched";
148
149 String LANGUAGE_SCRIPT = "CamelLanguageScript";
150 String LOG_DEBUG_BODY_MAX_CHARS = "CamelLogDebugBodyMaxChars";
151 String LOG_DEBUG_BODY_STREAMS = "CamelLogDebugStreams";
152 String LOOP_INDEX = "CamelLoopIndex";
153 String LOOP_SIZE = "CamelLoopSize";
154
155 String MAXIMUM_CACHE_POOL_SIZE = "CamelMaximumCachePoolSize";
156 String MAXIMUM_ENDPOINT_CACHE_SIZE = "CamelMaximumEndpointCacheSize";
157 String MESSAGE_HISTORY = "CamelMessageHistory";
158 String MULTICAST_INDEX = "CamelMulticastIndex";
159 String MULTICAST_COMPLETE = "CamelMulticastComplete";
160
161 String NOTIFY_EVENT = "CamelNotifyEvent";
162
163 String ON_COMPLETION = "CamelOnCompletion";
164 String OVERRULE_FILE_NAME = "CamelOverruleFileName";
165
166 String PARENT_UNIT_OF_WORK = "CamelParentUnitOfWork";
167
168 String RECIPIENT_LIST_ENDPOINT = "CamelRecipientListEndpoint";
169 String RECEIVED_TIMESTAMP = "CamelReceivedTimestamp";
170 String REDELIVERED = "CamelRedelivered";
171 String REDELIVERY_COUNTER = "CamelRedeliveryCounter";
172 String REDELIVERY_MAX_COUNTER = "CamelRedeliveryMaxCounter";
173 String REDELIVERY_EXHAUSTED = "CamelRedeliveryExhausted";
174 String REDELIVERY_DELAY = "CamelRedeliveryDelay";
175 String ROLLBACK_ONLY = "CamelRollbackOnly";
176 String ROLLBACK_ONLY_LAST = "CamelRollbackOnlyLast";
177 String ROUTE_STOP = "CamelRouteStop";
178
179 String SOAP_ACTION = "CamelSoapAction";
180 String SKIP_GZIP_ENCODING = "CamelSkipGzipEncoding";
181 String SLIP_ENDPOINT = "CamelSlipEndpoint";
182 String SPLIT_INDEX = "CamelSplitIndex";
183 String SPLIT_COMPLETE = "CamelSplitComplete";
184 String SPLIT_SIZE = "CamelSplitSize";
185
186 String TIMER_COUNTER = "CamelTimerCounter";
187 String TIMER_FIRED_TIME = "CamelTimerFiredTime";
188 String TIMER_NAME = "CamelTimerName";
189 String TIMER_PERIOD = "CamelTimerPeriod";
190 String TIMER_TIME = "CamelTimerTime";
191 String TO_ENDPOINT = "CamelToEndpoint";
192 String TRACE_EVENT = "CamelTraceEvent";
193 String TRACE_EVENT_NODE_ID = "CamelTraceEventNodeId";
194 String TRACE_EVENT_TIMESTAMP = "CamelTraceEventTimestamp";
195 String TRACE_EVENT_EXCHANGE = "CamelTraceEventExchange";
196 String TRANSFER_ENCODING = "Transfer-Encoding";
197
198 String UNIT_OF_WORK_EXHAUSTED = "CamelUnitOfWorkExhausted";
199 /**
200 * @deprecated UNIT_OF_WORK_PROCESS_SYNC is not in use and will be removed in future Camel release
201 */
202 @Deprecated
203 String UNIT_OF_WORK_PROCESS_SYNC = "CamelUnitOfWorkProcessSync";
204
205 String XSLT_FILE_NAME = "CamelXsltFileName";
206
207 /**
208 * Returns the {@link ExchangePattern} (MEP) of this exchange.
209 *
210 * @return the message exchange pattern of this exchange
211 */
212 ExchangePattern getPattern();
213
214 /**
215 * Allows the {@link ExchangePattern} (MEP) of this exchange to be customized.
216 *
217 * This typically won't be required as an exchange can be created with a specific MEP
218 * by calling {@link Endpoint#createExchange(ExchangePattern)} but it is here just in case
219 * it is needed.
220 *
221 * @param pattern the pattern
222 */
223 void setPattern(ExchangePattern pattern);
224
225 /**
226 * Returns a property associated with this exchange by name
227 *
228 * @param name the name of the property
229 * @return the value of the given property or <tt>null</tt> if there is no property for
230 * the given name
231 */
232 Object getProperty(String name);
233
234 /**
235 * Returns a property associated with this exchange by name
236 *
237 * @param name the name of the property
238 * @param defaultValue the default value to return if property was absent
239 * @return the value of the given property or <tt>defaultValue</tt> if there is no
240 * property for the given name
241 */
242 Object getProperty(String name, Object defaultValue);
243
244 /**
245 * Returns a property associated with this exchange by name and specifying
246 * the type required
247 *
248 * @param name the name of the property
249 * @param type the type of the property
250 * @return the value of the given property or <tt>null</tt> if there is no property for
251 * the given name or <tt>null</tt> if it cannot be converted to the given type
252 */
253 <T> T getProperty(String name, Class<T> type);
254
255 /**
256 * Returns a property associated with this exchange by name and specifying
257 * the type required
258 *
259 * @param name the name of the property
260 * @param defaultValue the default value to return if property was absent
261 * @param type the type of the property
262 * @return the value of the given property or <tt>defaultValue</tt> if there is no property for
263 * the given name or <tt>null</tt> if it cannot be converted to the given type
264 */
265 <T> T getProperty(String name, Object defaultValue, Class<T> type);
266
267 /**
268 * Sets a property on the exchange
269 *
270 * @param name of the property
271 * @param value to associate with the name
272 */
273 void setProperty(String name, Object value);
274
275 /**
276 * Removes the given property on the exchange
277 *
278 * @param name of the property
279 * @return the old value of the property
280 */
281 Object removeProperty(String name);
282
283 /**
284 * Returns all of the properties associated with the exchange
285 *
286 * @return all the headers in a Map
287 */
288 Map<String, Object> getProperties();
289
290 /**
291 * Returns whether any properties has been set
292 *
293 * @return <tt>true</tt> if any properties has been set
294 */
295 boolean hasProperties();
296
297 /**
298 * Returns the inbound request message
299 *
300 * @return the message
301 */
302 Message getIn();
303
304 /**
305 * Returns the inbound request message as the given type
306 *
307 * @param type the given type
308 * @return the message as the given type or <tt>null</tt> if not possible to covert to given type
309 */
310 <T> T getIn(Class<T> type);
311
312 /**
313 * Sets the inbound message instance
314 *
315 * @param in the inbound message
316 */
317 void setIn(Message in);
318
319 /**
320 * Returns the outbound message, lazily creating one if one has not already
321 * been associated with this exchange.
322 * <p/>
323 * <br/><b>Important:</b> If you want to change the current message, then use {@link #getIn()} instead as it will
324 * ensure headers etc. is kept and propagated when routing continues. Bottom line end users should rarely use
325 * this method.
326 * <p/>
327 * <br/>If you want to test whether an OUT message have been set or not, use the {@link #hasOut()} method.
328 * <p/>
329 * See also the class java doc for this {@link Exchange} for more details and this
330 * <a href="http://camel.apache.org/using-getin-or-getout-methods-on-exchange.html">FAQ entry</a>.
331 *
332 * @return the response
333 * @see #getIn()
334 */
335 Message getOut();
336
337 /**
338 * Returns the outbound request message as the given type
339 * <p/>
340 * <br/><b>Important:</b> If you want to change the current message, then use {@link #getIn()} instead as it will
341 * ensure headers etc. is kept and propagated when routing continues. Bottom line end users should rarely use
342 * this method.
343 * <p/>
344 * <br/>If you want to test whether an OUT message have been set or not, use the {@link #hasOut()} method.
345 * <p/>
346 * See also the class java doc for this {@link Exchange} for more details and this
347 * <a href="http://camel.apache.org/using-getin-or-getout-methods-on-exchange.html">FAQ entry</a>.
348 *
349 * @param type the given type
350 * @return the message as the given type or <tt>null</tt> if not possible to covert to given type
351 * @see #getIn(Class)
352 */
353 <T> T getOut(Class<T> type);
354
355 /**
356 * Returns whether an OUT message has been set or not.
357 *
358 * @return <tt>true</tt> if an OUT message exists, <tt>false</tt> otherwise.
359 */
360 boolean hasOut();
361
362 /**
363 * Sets the outbound message
364 *
365 * @param out the outbound message
366 */
367 void setOut(Message out);
368
369 /**
370 * Returns the exception associated with this exchange
371 *
372 * @return the exception (or null if no faults)
373 */
374 Exception getException();
375
376 /**
377 * Returns the exception associated with this exchange.
378 * <p/>
379 * Is used to get the caused exception that typically have been wrapped in some sort
380 * of Camel wrapper exception
381 * <p/>
382 * The strategy is to look in the exception hierarchy to find the first given cause that matches the type.
383 * Will start from the bottom (the real cause) and walk upwards.
384 *
385 * @param type the exception type
386 * @return the exception (or <tt>null</tt> if no caused exception matched)
387 */
388 <T> T getException(Class<T> type);
389
390 /**
391 * Sets the exception associated with this exchange
392 * <p/>
393 * Camel will wrap {@link Throwable} into {@link Exception} type to
394 * accommodate for the {@link #getException()} method returning a plain {@link Exception} type.
395 *
396 * @param t the caused exception
397 */
398 void setException(Throwable t);
399
400 /**
401 * Returns true if this exchange failed due to either an exception or fault
402 *
403 * @return true if this exchange failed due to either an exception or fault
404 * @see Exchange#getException()
405 * @see Message#setFault(boolean)
406 * @see Message#isFault()
407 */
408 boolean isFailed();
409
410 /**
411 * Returns true if this exchange is transacted
412 */
413 boolean isTransacted();
414
415 /**
416 * Returns true if this exchange is an external initiated redelivered message (such as a JMS broker).
417 * <p/>
418 * <b>Important: </b> It is not always possible to determine if the message is a redelivery
419 * or not, and therefore <tt>null</tt> is returned. Such an example would be a JDBC message.
420 * However JMS brokers provides details if a message is redelivered.
421 *
422 * @return <tt>true</tt> if redelivered, <tt>false</tt> if not, <tt>null</tt> if not able to determine
423 */
424 Boolean isExternalRedelivered();
425
426 /**
427 * Returns true if this exchange is marked for rollback
428 */
429 boolean isRollbackOnly();
430
431 /**
432 * Returns the container so that a processor can resolve endpoints from URIs
433 *
434 * @return the container which owns this exchange
435 */
436 CamelContext getContext();
437
438 /**
439 * Creates a copy of the current message exchange so that it can be
440 * forwarded to another destination
441 */
442 Exchange copy();
443
444 /**
445 * Returns the endpoint which originated this message exchange if a consumer on an endpoint
446 * created the message exchange, otherwise this property will be <tt>null</tt>
447 */
448 Endpoint getFromEndpoint();
449
450 /**
451 * Sets the endpoint which originated this message exchange. This method
452 * should typically only be called by {@link org.apache.camel.Endpoint} implementations
453 *
454 * @param fromEndpoint the endpoint which is originating this message exchange
455 */
456 void setFromEndpoint(Endpoint fromEndpoint);
457
458 /**
459 * Returns the route id which originated this message exchange if a route consumer on an endpoint
460 * created the message exchange, otherwise this property will be <tt>null</tt>
461 */
462 String getFromRouteId();
463
464 /**
465 * Sets the route id which originated this message exchange. This method
466 * should typically only be called by the internal framework.
467 *
468 * @param fromRouteId the from route id
469 */
470 void setFromRouteId(String fromRouteId);
471
472 /**
473 * Returns the unit of work that this exchange belongs to; which may map to
474 * zero, one or more physical transactions
475 */
476 UnitOfWork getUnitOfWork();
477
478 /**
479 * Sets the unit of work that this exchange belongs to; which may map to
480 * zero, one or more physical transactions
481 */
482 void setUnitOfWork(UnitOfWork unitOfWork);
483
484 /**
485 * Returns the exchange id (unique)
486 */
487 String getExchangeId();
488
489 /**
490 * Set the exchange id
491 */
492 void setExchangeId(String id);
493
494 /**
495 * Adds a {@link org.apache.camel.spi.Synchronization} to be invoked as callback when
496 * this exchange is completed.
497 *
498 * @param onCompletion the callback to invoke on completion of this exchange
499 */
500 void addOnCompletion(Synchronization onCompletion);
501
502 /**
503 * Checks if the passed {@link org.apache.camel.spi.Synchronization} instance is
504 * already contained on this exchange.
505 *
506 * @param onCompletion the callback instance that is being checked for
507 * @return <tt>true</tt>, if callback instance is already contained on this exchange, else <tt>false</tt>
508 */
509 boolean containsOnCompletion(Synchronization onCompletion);
510
511 /**
512 * Handover all the on completions from this exchange to the target exchange.
513 *
514 * @param target the target exchange
515 */
516 void handoverCompletions(Exchange target);
517
518 /**
519 * Handover all the on completions from this exchange
520 *
521 * @return the on completions
522 */
523 List<Synchronization> handoverCompletions();
524
525 }