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