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