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 RECEIVED_TIMESTAMP = "CamelReceivedTimestamp";
147 String REDELIVERED = "CamelRedelivered";
148 String REDELIVERY_COUNTER = "CamelRedeliveryCounter";
149 String REDELIVERY_MAX_COUNTER = "CamelRedeliveryMaxCounter";
150 String REDELIVERY_EXHAUSTED = "CamelRedeliveryExhausted";
151 String ROLLBACK_ONLY = "CamelRollbackOnly";
152 String ROLLBACK_ONLY_LAST = "CamelRollbackOnlyLast";
153 String ROUTE_STOP = "CamelRouteStop";
154
155 String SOAP_ACTION = "CamelSoapAction";
156 String SKIP_GZIP_ENCODING = "CamelSkipGzipEncoding";
157 String SLIP_ENDPOINT = "CamelSlipEndpoint";
158 String SPLIT_INDEX = "CamelSplitIndex";
159 String SPLIT_COMPLETE = "CamelSplitComplete";
160 String SPLIT_SIZE = "CamelSplitSize";
161
162 String TIMER_FIRED_TIME = "CamelTimerFiredTime";
163 String TIMER_NAME = "CamelTimerName";
164 String TIMER_PERIOD = "CamelTimerPeriod";
165 String TIMER_TIME = "CamelTimerTime";
166 String TO_ENDPOINT = "CamelToEndpoint";
167 String TRACE_EVENT = "CamelTraceEvent";
168 String TRACE_EVENT_NODE_ID = "CamelTraceEventNodeId";
169 String TRACE_EVENT_TIMESTAMP = "CamelTraceEventTimestamp";
170 String TRACE_EVENT_EXCHANGE = "CamelTraceEventExchange";
171 String TRANSFER_ENCODING = "Transfer-Encoding";
172
173 String XSLT_FILE_NAME = "CamelXsltFileName";
174
175 /**
176 * Returns the {@link ExchangePattern} (MEP) of this exchange.
177 *
178 * @return the message exchange pattern of this exchange
179 */
180 ExchangePattern getPattern();
181
182 /**
183 * Allows the {@link ExchangePattern} (MEP) of this exchange to be customized.
184 *
185 * This typically won't be required as an exchange can be created with a specific MEP
186 * by calling {@link Endpoint#createExchange(ExchangePattern)} but it is here just in case
187 * it is needed.
188 *
189 * @param pattern the pattern
190 */
191 void setPattern(ExchangePattern pattern);
192
193 /**
194 * Returns a property associated with this exchange by name
195 *
196 * @param name the name of the property
197 * @return the value of the given property or <tt>null</tt> if there is no property for
198 * the given name
199 */
200 Object getProperty(String name);
201
202 /**
203 * Returns a property associated with this exchange by name
204 *
205 * @param name the name of the property
206 * @param defaultValue the default value to return if property was absent
207 * @return the value of the given property or <tt>defaultValue</tt> if there is no
208 * property for the given name
209 */
210 Object getProperty(String name, Object defaultValue);
211
212 /**
213 * Returns a property associated with this exchange by name and specifying
214 * the type required
215 *
216 * @param name the name of the property
217 * @param type the type of the property
218 * @return the value of the given property or <tt>null</tt> if there is no property for
219 * the given name or <tt>null</tt> if it cannot be converted to the given type
220 */
221 <T> T getProperty(String name, Class<T> type);
222
223 /**
224 * Returns a property associated with this exchange by name and specifying
225 * the type required
226 *
227 * @param name the name of the property
228 * @param defaultValue the default value to return if property was absent
229 * @param type the type of the property
230 * @return the value of the given property or <tt>defaultValue</tt> if there is no property for
231 * the given name or <tt>null</tt> if it cannot be converted to the given type
232 */
233 <T> T getProperty(String name, Object defaultValue, Class<T> type);
234
235 /**
236 * Sets a property on the exchange
237 *
238 * @param name of the property
239 * @param value to associate with the name
240 */
241 void setProperty(String name, Object value);
242
243 /**
244 * Removes the given property on the exchange
245 *
246 * @param name of the property
247 * @return the old value of the property
248 */
249 Object removeProperty(String name);
250
251 /**
252 * Returns all of the properties associated with the exchange
253 *
254 * @return all the headers in a Map
255 */
256 Map<String, Object> getProperties();
257
258 /**
259 * Returns whether any properties has been set
260 *
261 * @return <tt>true</tt> if any properties has been set
262 */
263 boolean hasProperties();
264
265 /**
266 * Returns the inbound request message
267 *
268 * @return the message
269 */
270 Message getIn();
271
272 /**
273 * Returns the inbound request message as the given type
274 *
275 * @param type the given type
276 * @return the message as the given type or <tt>null</tt> if not possible to covert to given type
277 */
278 <T> T getIn(Class<T> type);
279
280 /**
281 * Sets the inbound message instance
282 *
283 * @param in the inbound message
284 */
285 void setIn(Message in);
286
287 /**
288 * Returns the outbound message, lazily creating one if one has not already
289 * been associated with this exchange.
290 * <p/>
291 * <br/><b>Important:</b> If you want to change the current message, then use {@link #getIn()} instead as it will
292 * ensure headers etc. is kept and propagated when routing continues. Bottom line end users should rarely use
293 * this method.
294 * <p/>
295 * <br/>If you want to test whether an OUT message have been set or not, use the {@link #hasOut()} method.
296 * <p/>
297 * See also the class java doc for this {@link Exchange} for more details and this
298 * <a href="http://camel.apache.org/using-getin-or-getout-methods-on-exchange.html">FAQ entry</a>.
299 *
300 * @return the response
301 * @see #getIn()
302 */
303 Message getOut();
304
305 /**
306 * Returns the outbound request message as the given type
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 * @param type the given type
318 * @return the message as the given type or <tt>null</tt> if not possible to covert to given type
319 * @see #getIn(Class)
320 */
321 <T> T getOut(Class<T> type);
322
323 /**
324 * Returns whether an OUT message has been set or not.
325 *
326 * @return <tt>true</tt> if an OUT message exists, <tt>false</tt> otherwise.
327 */
328 boolean hasOut();
329
330 /**
331 * Sets the outbound message
332 *
333 * @param out the outbound message
334 */
335 void setOut(Message out);
336
337 /**
338 * Returns the exception associated with this exchange
339 *
340 * @return the exception (or null if no faults)
341 */
342 Exception getException();
343
344 /**
345 * Returns the exception associated with this exchange.
346 * <p/>
347 * Is used to get the caused exception that typically have been wrapped in some sort
348 * of Camel wrapper exception
349 * <p/>
350 * The strategy is to look in the exception hierarchy to find the first given cause that matches the type.
351 * Will start from the bottom (the real cause) and walk upwards.
352 *
353 * @param type the exception type
354 * @return the exception (or <tt>null</tt> if no caused exception matched)
355 */
356 <T> T getException(Class<T> type);
357
358 /**
359 * Sets the exception associated with this exchange
360 * <p/>
361 * Camel will wrap {@link Throwable} into {@link Exception} type to
362 * accommodate for the {@link #getException()} method returning a plain {@link Exception} type.
363 *
364 * @param t the caused exception
365 */
366 void setException(Throwable t);
367
368 /**
369 * Returns true if this exchange failed due to either an exception or fault
370 *
371 * @return true if this exchange failed due to either an exception or fault
372 * @see Exchange#getException()
373 * @see Message#setFault(boolean)
374 * @see Message#isFault()
375 */
376 boolean isFailed();
377
378 /**
379 * Returns true if this exchange is transacted
380 */
381 boolean isTransacted();
382
383 /**
384 * Returns true if this exchange is marked for rollback
385 */
386 boolean isRollbackOnly();
387
388 /**
389 * Returns the container so that a processor can resolve endpoints from URIs
390 *
391 * @return the container which owns this exchange
392 */
393 CamelContext getContext();
394
395 /**
396 * Creates a copy of the current message exchange so that it can be
397 * forwarded to another destination
398 */
399 Exchange copy();
400
401 /**
402 * Returns the endpoint which originated this message exchange if a consumer on an endpoint
403 * created the message exchange, otherwise this property will be <tt>null</tt>
404 */
405 Endpoint getFromEndpoint();
406
407 /**
408 * Sets the endpoint which originated this message exchange. This method
409 * should typically only be called by {@link org.apache.camel.Endpoint} implementations
410 *
411 * @param fromEndpoint the endpoint which is originating this message exchange
412 */
413 void setFromEndpoint(Endpoint fromEndpoint);
414
415 /**
416 * Returns the route id which originated this message exchange if a route consumer on an endpoint
417 * created the message exchange, otherwise this property will be <tt>null</tt>
418 */
419 String getFromRouteId();
420
421 /**
422 * Sets the route id which originated this message exchange. This method
423 * should typically only be called by the internal framework.
424 *
425 * @param fromRouteId the from route id
426 */
427 void setFromRouteId(String fromRouteId);
428
429 /**
430 * Returns the unit of work that this exchange belongs to; which may map to
431 * zero, one or more physical transactions
432 */
433 UnitOfWork getUnitOfWork();
434
435 /**
436 * Sets the unit of work that this exchange belongs to; which may map to
437 * zero, one or more physical transactions
438 */
439 void setUnitOfWork(UnitOfWork unitOfWork);
440
441 /**
442 * Returns the exchange id (unique)
443 */
444 String getExchangeId();
445
446 /**
447 * Set the exchange id
448 */
449 void setExchangeId(String id);
450
451 /**
452 * Adds a {@link org.apache.camel.spi.Synchronization} to be invoked as callback when
453 * this exchange is completed.
454 *
455 * @param onCompletion the callback to invoke on completion of this exchange
456 */
457 void addOnCompletion(Synchronization onCompletion);
458
459 /**
460 * Handover all the on completions from this exchange to the target exchange.
461 *
462 * @param target the target exchange
463 */
464 void handoverCompletions(Exchange target);
465
466 /**
467 * Handover all the on completions from this exchange
468 *
469 * @return the on completions
470 */
471 List<Synchronization> handoverCompletions();
472
473 }