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_RAW_QUERY = "CamelHttpRawQuery"; 140 String HTTP_RESPONSE_CODE = "CamelHttpResponseCode"; 141 String HTTP_URI = "CamelHttpUri"; 142 String HTTP_URL = "CamelHttpUrl"; 143 String HTTP_CHUNKED = "CamelHttpChunked"; 144 String HTTP_SERVLET_REQUEST = "CamelHttpServletRequest"; 145 String HTTP_SERVLET_RESPONSE = "CamelHttpServletResponse"; 146 147 String INTERCEPTED_ENDPOINT = "CamelInterceptedEndpoint"; 148 String INTERCEPT_SEND_TO_ENDPOINT_WHEN_MATCHED = "CamelInterceptSendToEndpointWhenMatched"; 149 150 String LANGUAGE_SCRIPT = "CamelLanguageScript"; 151 String LOG_DEBUG_BODY_MAX_CHARS = "CamelLogDebugBodyMaxChars"; 152 String LOG_DEBUG_BODY_STREAMS = "CamelLogDebugStreams"; 153 String LOOP_INDEX = "CamelLoopIndex"; 154 String LOOP_SIZE = "CamelLoopSize"; 155 156 String MAXIMUM_CACHE_POOL_SIZE = "CamelMaximumCachePoolSize"; 157 String MAXIMUM_ENDPOINT_CACHE_SIZE = "CamelMaximumEndpointCacheSize"; 158 String MESSAGE_HISTORY = "CamelMessageHistory"; 159 String MULTICAST_INDEX = "CamelMulticastIndex"; 160 String MULTICAST_COMPLETE = "CamelMulticastComplete"; 161 162 String NOTIFY_EVENT = "CamelNotifyEvent"; 163 164 String ON_COMPLETION = "CamelOnCompletion"; 165 String OVERRULE_FILE_NAME = "CamelOverruleFileName"; 166 167 String PARENT_UNIT_OF_WORK = "CamelParentUnitOfWork"; 168 169 String RECIPIENT_LIST_ENDPOINT = "CamelRecipientListEndpoint"; 170 String RECEIVED_TIMESTAMP = "CamelReceivedTimestamp"; 171 String REDELIVERED = "CamelRedelivered"; 172 String REDELIVERY_COUNTER = "CamelRedeliveryCounter"; 173 String REDELIVERY_MAX_COUNTER = "CamelRedeliveryMaxCounter"; 174 String REDELIVERY_EXHAUSTED = "CamelRedeliveryExhausted"; 175 String REDELIVERY_DELAY = "CamelRedeliveryDelay"; 176 String ROLLBACK_ONLY = "CamelRollbackOnly"; 177 String ROLLBACK_ONLY_LAST = "CamelRollbackOnlyLast"; 178 String ROUTE_STOP = "CamelRouteStop"; 179 180 String SOAP_ACTION = "CamelSoapAction"; 181 String SKIP_GZIP_ENCODING = "CamelSkipGzipEncoding"; 182 String SLIP_ENDPOINT = "CamelSlipEndpoint"; 183 String SPLIT_INDEX = "CamelSplitIndex"; 184 String SPLIT_COMPLETE = "CamelSplitComplete"; 185 String SPLIT_SIZE = "CamelSplitSize"; 186 187 String TIMER_COUNTER = "CamelTimerCounter"; 188 String TIMER_FIRED_TIME = "CamelTimerFiredTime"; 189 String TIMER_NAME = "CamelTimerName"; 190 String TIMER_PERIOD = "CamelTimerPeriod"; 191 String TIMER_TIME = "CamelTimerTime"; 192 String TO_ENDPOINT = "CamelToEndpoint"; 193 String TRACE_EVENT = "CamelTraceEvent"; 194 String TRACE_EVENT_NODE_ID = "CamelTraceEventNodeId"; 195 String TRACE_EVENT_TIMESTAMP = "CamelTraceEventTimestamp"; 196 String TRACE_EVENT_EXCHANGE = "CamelTraceEventExchange"; 197 String TRY_ROUTE_BLOCK = "TryRouteBlock"; 198 String TRANSFER_ENCODING = "Transfer-Encoding"; 199 200 String UNIT_OF_WORK_EXHAUSTED = "CamelUnitOfWorkExhausted"; 201 /** 202 * @deprecated UNIT_OF_WORK_PROCESS_SYNC is not in use and will be removed in future Camel release 203 */ 204 @Deprecated 205 String UNIT_OF_WORK_PROCESS_SYNC = "CamelUnitOfWorkProcessSync"; 206 207 String XSLT_FILE_NAME = "CamelXsltFileName"; 208 209 /** 210 * Returns the {@link ExchangePattern} (MEP) of this exchange. 211 * 212 * @return the message exchange pattern of this exchange 213 */ 214 ExchangePattern getPattern(); 215 216 /** 217 * Allows the {@link ExchangePattern} (MEP) of this exchange to be customized. 218 * 219 * This typically won't be required as an exchange can be created with a specific MEP 220 * by calling {@link Endpoint#createExchange(ExchangePattern)} but it is here just in case 221 * it is needed. 222 * 223 * @param pattern the pattern 224 */ 225 void setPattern(ExchangePattern pattern); 226 227 /** 228 * Returns a property associated with this exchange by name 229 * 230 * @param name the name of the property 231 * @return the value of the given property or <tt>null</tt> if there is no property for 232 * the given name 233 */ 234 Object getProperty(String name); 235 236 /** 237 * Returns a property associated with this exchange by name 238 * 239 * @param name the name of the property 240 * @param defaultValue the default value to return if property was absent 241 * @return the value of the given property or <tt>defaultValue</tt> if there is no 242 * property for the given name 243 */ 244 Object getProperty(String name, Object defaultValue); 245 246 /** 247 * Returns a property associated with this exchange by name and specifying 248 * the type required 249 * 250 * @param name the name of the property 251 * @param type the type of the property 252 * @return the value of the given property or <tt>null</tt> if there is no property for 253 * the given name or <tt>null</tt> if it cannot be converted to the given type 254 */ 255 <T> T getProperty(String name, Class<T> type); 256 257 /** 258 * Returns a property associated with this exchange by name and specifying 259 * the type required 260 * 261 * @param name the name of the property 262 * @param defaultValue the default value to return if property was absent 263 * @param type the type of the property 264 * @return the value of the given property or <tt>defaultValue</tt> if there is no property for 265 * the given name or <tt>null</tt> if it cannot be converted to the given type 266 */ 267 <T> T getProperty(String name, Object defaultValue, Class<T> type); 268 269 /** 270 * Sets a property on the exchange 271 * 272 * @param name of the property 273 * @param value to associate with the name 274 */ 275 void setProperty(String name, Object value); 276 277 /** 278 * Removes the given property on the exchange 279 * 280 * @param name of the property 281 * @return the old value of the property 282 */ 283 Object removeProperty(String name); 284 285 /** 286 * Returns all of the properties associated with the exchange 287 * 288 * @return all the headers in a Map 289 */ 290 Map<String, Object> getProperties(); 291 292 /** 293 * Returns whether any properties has been set 294 * 295 * @return <tt>true</tt> if any properties has been set 296 */ 297 boolean hasProperties(); 298 299 /** 300 * Returns the inbound request message 301 * 302 * @return the message 303 */ 304 Message getIn(); 305 306 /** 307 * Returns the inbound request message as the given type 308 * 309 * @param type the given type 310 * @return the message as the given type or <tt>null</tt> if not possible to covert to given type 311 */ 312 <T> T getIn(Class<T> type); 313 314 /** 315 * Sets the inbound message instance 316 * 317 * @param in the inbound message 318 */ 319 void setIn(Message in); 320 321 /** 322 * Returns the outbound message, lazily creating one if one has not already 323 * been associated with this exchange. 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 * @return the response 335 * @see #getIn() 336 */ 337 Message getOut(); 338 339 /** 340 * Returns the outbound request message as the given type 341 * <p/> 342 * <br/><b>Important:</b> If you want to change the current message, then use {@link #getIn()} instead as it will 343 * ensure headers etc. is kept and propagated when routing continues. Bottom line end users should rarely use 344 * this method. 345 * <p/> 346 * <br/>If you want to test whether an OUT message have been set or not, use the {@link #hasOut()} method. 347 * <p/> 348 * See also the class java doc for this {@link Exchange} for more details and this 349 * <a href="http://camel.apache.org/using-getin-or-getout-methods-on-exchange.html">FAQ entry</a>. 350 * 351 * @param type the given type 352 * @return the message as the given type or <tt>null</tt> if not possible to covert to given type 353 * @see #getIn(Class) 354 */ 355 <T> T getOut(Class<T> type); 356 357 /** 358 * Returns whether an OUT message has been set or not. 359 * 360 * @return <tt>true</tt> if an OUT message exists, <tt>false</tt> otherwise. 361 */ 362 boolean hasOut(); 363 364 /** 365 * Sets the outbound message 366 * 367 * @param out the outbound message 368 */ 369 void setOut(Message out); 370 371 /** 372 * Returns the exception associated with this exchange 373 * 374 * @return the exception (or null if no faults) 375 */ 376 Exception getException(); 377 378 /** 379 * Returns the exception associated with this exchange. 380 * <p/> 381 * Is used to get the caused exception that typically have been wrapped in some sort 382 * of Camel wrapper exception 383 * <p/> 384 * The strategy is to look in the exception hierarchy to find the first given cause that matches the type. 385 * Will start from the bottom (the real cause) and walk upwards. 386 * 387 * @param type the exception type 388 * @return the exception (or <tt>null</tt> if no caused exception matched) 389 */ 390 <T> T getException(Class<T> type); 391 392 /** 393 * Sets the exception associated with this exchange 394 * <p/> 395 * Camel will wrap {@link Throwable} into {@link Exception} type to 396 * accommodate for the {@link #getException()} method returning a plain {@link Exception} type. 397 * 398 * @param t the caused exception 399 */ 400 void setException(Throwable t); 401 402 /** 403 * Returns true if this exchange failed due to either an exception or fault 404 * 405 * @return true if this exchange failed due to either an exception or fault 406 * @see Exchange#getException() 407 * @see Message#setFault(boolean) 408 * @see Message#isFault() 409 */ 410 boolean isFailed(); 411 412 /** 413 * Returns true if this exchange is transacted 414 */ 415 boolean isTransacted(); 416 417 /** 418 * Returns true if this exchange is an external initiated redelivered message (such as a JMS broker). 419 * <p/> 420 * <b>Important: </b> It is not always possible to determine if the message is a redelivery 421 * or not, and therefore <tt>null</tt> is returned. Such an example would be a JDBC message. 422 * However JMS brokers provides details if a message is redelivered. 423 * 424 * @return <tt>true</tt> if redelivered, <tt>false</tt> if not, <tt>null</tt> if not able to determine 425 */ 426 Boolean isExternalRedelivered(); 427 428 /** 429 * Returns true if this exchange is marked for rollback 430 */ 431 boolean isRollbackOnly(); 432 433 /** 434 * Returns the container so that a processor can resolve endpoints from URIs 435 * 436 * @return the container which owns this exchange 437 */ 438 CamelContext getContext(); 439 440 /** 441 * Creates a copy of the current message exchange so that it can be 442 * forwarded to another destination 443 */ 444 Exchange copy(); 445 446 /** 447 * Returns the endpoint which originated this message exchange if a consumer on an endpoint 448 * created the message exchange, otherwise this property will be <tt>null</tt> 449 */ 450 Endpoint getFromEndpoint(); 451 452 /** 453 * Sets the endpoint which originated this message exchange. This method 454 * should typically only be called by {@link org.apache.camel.Endpoint} implementations 455 * 456 * @param fromEndpoint the endpoint which is originating this message exchange 457 */ 458 void setFromEndpoint(Endpoint fromEndpoint); 459 460 /** 461 * Returns the route id which originated this message exchange if a route consumer on an endpoint 462 * created the message exchange, otherwise this property will be <tt>null</tt> 463 */ 464 String getFromRouteId(); 465 466 /** 467 * Sets the route id which originated this message exchange. This method 468 * should typically only be called by the internal framework. 469 * 470 * @param fromRouteId the from route id 471 */ 472 void setFromRouteId(String fromRouteId); 473 474 /** 475 * Returns the unit of work that this exchange belongs to; which may map to 476 * zero, one or more physical transactions 477 */ 478 UnitOfWork getUnitOfWork(); 479 480 /** 481 * Sets the unit of work that this exchange belongs to; which may map to 482 * zero, one or more physical transactions 483 */ 484 void setUnitOfWork(UnitOfWork unitOfWork); 485 486 /** 487 * Returns the exchange id (unique) 488 */ 489 String getExchangeId(); 490 491 /** 492 * Set the exchange id 493 */ 494 void setExchangeId(String id); 495 496 /** 497 * Adds a {@link org.apache.camel.spi.Synchronization} to be invoked as callback when 498 * this exchange is completed. 499 * 500 * @param onCompletion the callback to invoke on completion of this exchange 501 */ 502 void addOnCompletion(Synchronization onCompletion); 503 504 /** 505 * Checks if the passed {@link org.apache.camel.spi.Synchronization} instance is 506 * already contained on this exchange. 507 * 508 * @param onCompletion the callback instance that is being checked for 509 * @return <tt>true</tt>, if callback instance is already contained on this exchange, else <tt>false</tt> 510 */ 511 boolean containsOnCompletion(Synchronization onCompletion); 512 513 /** 514 * Handover all the on completions from this exchange to the target exchange. 515 * 516 * @param target the target exchange 517 */ 518 void handoverCompletions(Exchange target); 519 520 /** 521 * Handover all the on completions from this exchange 522 * 523 * @return the on completions 524 */ 525 List<Synchronization> handoverCompletions(); 526 527 }