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