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 FAILURE_ROUTE_ID = "CamelFailureRouteId"; 115 String FILTER_NON_XML_CHARS = "CamelFilterNonXmlChars"; 116 String FILE_LOCAL_WORK_PATH = "CamelFileLocalWorkPath"; 117 String FILE_NAME = "CamelFileName"; 118 String FILE_NAME_ONLY = "CamelFileNameOnly"; 119 String FILE_NAME_PRODUCED = "CamelFileNameProduced"; 120 String FILE_PATH = "CamelFilePath"; 121 String FILE_PARENT = "CamelFileParent"; 122 String FILE_LAST_MODIFIED = "CamelFileLastModified"; 123 String FILE_LENGTH = "CamelFileLength"; 124 String FILTER_MATCHED = "CamelFilterMatched"; 125 String FILE_LOCK_FILE_ACQUIRED = "CamelFileLockFileAcquired"; 126 127 String GROUPED_EXCHANGE = "CamelGroupedExchange"; 128 129 String HTTP_BASE_URI = "CamelHttpBaseUri"; 130 String HTTP_CHARACTER_ENCODING = "CamelHttpCharacterEncoding"; 131 String HTTP_METHOD = "CamelHttpMethod"; 132 String HTTP_PATH = "CamelHttpPath"; 133 String HTTP_PROTOCOL_VERSION = "CamelHttpProtocolVersion"; 134 String HTTP_QUERY = "CamelHttpQuery"; 135 String HTTP_RESPONSE_CODE = "CamelHttpResponseCode"; 136 String HTTP_URI = "CamelHttpUri"; 137 String HTTP_URL = "CamelHttpUrl"; 138 String HTTP_CHUNKED = "CamelHttpChunked"; 139 String HTTP_SERVLET_REQUEST = "CamelHttpServletRequest"; 140 String HTTP_SERVLET_RESPONSE = "CamelHttpServletResponse"; 141 142 String INTERCEPTED_ENDPOINT = "CamelInterceptedEndpoint"; 143 String INTERCEPT_SEND_TO_ENDPOINT_WHEN_MATCHED = "CamelInterceptSendToEndpointWhenMatched"; 144 145 String LANGUAGE_SCRIPT = "CamelLanguageScript"; 146 String LOG_DEBUG_BODY_MAX_CHARS = "CamelLogDebugBodyMaxChars"; 147 String LOG_DEBUG_BODY_STREAMS = "CamelLogDebugStreams"; 148 String LOOP_INDEX = "CamelLoopIndex"; 149 String LOOP_SIZE = "CamelLoopSize"; 150 151 String MAXIMUM_CACHE_POOL_SIZE = "CamelMaximumCachePoolSize"; 152 String MAXIMUM_ENDPOINT_CACHE_SIZE = "CamelMaximumEndpointCacheSize"; 153 String MULTICAST_INDEX = "CamelMulticastIndex"; 154 String MULTICAST_COMPLETE = "CamelMulticastComplete"; 155 156 String NOTIFY_EVENT = "CamelNotifyEvent"; 157 158 String ON_COMPLETION = "CamelOnCompletion"; 159 160 String PARENT_UNIT_OF_WORK = "CamelParentUnitOfWork"; 161 162 String RECEIVED_TIMESTAMP = "CamelReceivedTimestamp"; 163 String REDELIVERED = "CamelRedelivered"; 164 String REDELIVERY_COUNTER = "CamelRedeliveryCounter"; 165 String REDELIVERY_MAX_COUNTER = "CamelRedeliveryMaxCounter"; 166 String REDELIVERY_EXHAUSTED = "CamelRedeliveryExhausted"; 167 String REDELIVERY_DELAY = "CamelRedeliveryDelay"; 168 String ROLLBACK_ONLY = "CamelRollbackOnly"; 169 String ROLLBACK_ONLY_LAST = "CamelRollbackOnlyLast"; 170 String ROUTE_STOP = "CamelRouteStop"; 171 172 String SOAP_ACTION = "CamelSoapAction"; 173 String SKIP_GZIP_ENCODING = "CamelSkipGzipEncoding"; 174 String SLIP_ENDPOINT = "CamelSlipEndpoint"; 175 String SPLIT_INDEX = "CamelSplitIndex"; 176 String SPLIT_COMPLETE = "CamelSplitComplete"; 177 String SPLIT_SIZE = "CamelSplitSize"; 178 179 String TIMER_COUNTER = "CamelTimerCounter"; 180 String TIMER_FIRED_TIME = "CamelTimerFiredTime"; 181 String TIMER_NAME = "CamelTimerName"; 182 String TIMER_PERIOD = "CamelTimerPeriod"; 183 String TIMER_TIME = "CamelTimerTime"; 184 String TO_ENDPOINT = "CamelToEndpoint"; 185 String TRACE_EVENT = "CamelTraceEvent"; 186 String TRACE_EVENT_NODE_ID = "CamelTraceEventNodeId"; 187 String TRACE_EVENT_TIMESTAMP = "CamelTraceEventTimestamp"; 188 String TRACE_EVENT_EXCHANGE = "CamelTraceEventExchange"; 189 String TRANSFER_ENCODING = "Transfer-Encoding"; 190 191 String UNIT_OF_WORK_EXHAUSTED = "CamelUnitOfWorkExhausted"; 192 String UNIT_OF_WORK_PROCESS_SYNC = "CamelUnitOfWorkProcessSync"; 193 194 String XSLT_FILE_NAME = "CamelXsltFileName"; 195 196 /** 197 * Returns the {@link ExchangePattern} (MEP) of this exchange. 198 * 199 * @return the message exchange pattern of this exchange 200 */ 201 ExchangePattern getPattern(); 202 203 /** 204 * Allows the {@link ExchangePattern} (MEP) of this exchange to be customized. 205 * 206 * This typically won't be required as an exchange can be created with a specific MEP 207 * by calling {@link Endpoint#createExchange(ExchangePattern)} but it is here just in case 208 * it is needed. 209 * 210 * @param pattern the pattern 211 */ 212 void setPattern(ExchangePattern pattern); 213 214 /** 215 * Returns a property associated with this exchange by name 216 * 217 * @param name the name 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 220 */ 221 Object getProperty(String name); 222 223 /** 224 * Returns a property associated with this exchange by name 225 * 226 * @param name the name of the property 227 * @param defaultValue the default value to return if property was absent 228 * @return the value of the given property or <tt>defaultValue</tt> if there is no 229 * property for the given name 230 */ 231 Object getProperty(String name, Object defaultValue); 232 233 /** 234 * Returns a property associated with this exchange by name and specifying 235 * the type required 236 * 237 * @param name the name of the property 238 * @param type the type of the property 239 * @return the value of the given property or <tt>null</tt> if there is no property for 240 * the given name or <tt>null</tt> if it cannot be converted to the given type 241 */ 242 <T> T getProperty(String name, Class<T> type); 243 244 /** 245 * Returns a property associated with this exchange by name and specifying 246 * the type required 247 * 248 * @param name the name of the property 249 * @param defaultValue the default value to return if property was absent 250 * @param type the type of the property 251 * @return the value of the given property or <tt>defaultValue</tt> if there is no property for 252 * the given name or <tt>null</tt> if it cannot be converted to the given type 253 */ 254 <T> T getProperty(String name, Object defaultValue, Class<T> type); 255 256 /** 257 * Sets a property on the exchange 258 * 259 * @param name of the property 260 * @param value to associate with the name 261 */ 262 void setProperty(String name, Object value); 263 264 /** 265 * Removes the given property on the exchange 266 * 267 * @param name of the property 268 * @return the old value of the property 269 */ 270 Object removeProperty(String name); 271 272 /** 273 * Returns all of the properties associated with the exchange 274 * 275 * @return all the headers in a Map 276 */ 277 Map<String, Object> getProperties(); 278 279 /** 280 * Returns whether any properties has been set 281 * 282 * @return <tt>true</tt> if any properties has been set 283 */ 284 boolean hasProperties(); 285 286 /** 287 * Returns the inbound request message 288 * 289 * @return the message 290 */ 291 Message getIn(); 292 293 /** 294 * Returns the inbound request message as the given type 295 * 296 * @param type the given type 297 * @return the message as the given type or <tt>null</tt> if not possible to covert to given type 298 */ 299 <T> T getIn(Class<T> type); 300 301 /** 302 * Sets the inbound message instance 303 * 304 * @param in the inbound message 305 */ 306 void setIn(Message in); 307 308 /** 309 * Returns the outbound message, lazily creating one if one has not already 310 * been associated with this exchange. 311 * <p/> 312 * <br/><b>Important:</b> If you want to change the current message, then use {@link #getIn()} instead as it will 313 * ensure headers etc. is kept and propagated when routing continues. Bottom line end users should rarely use 314 * this method. 315 * <p/> 316 * <br/>If you want to test whether an OUT message have been set or not, use the {@link #hasOut()} method. 317 * <p/> 318 * See also the class java doc for this {@link Exchange} for more details and this 319 * <a href="http://camel.apache.org/using-getin-or-getout-methods-on-exchange.html">FAQ entry</a>. 320 * 321 * @return the response 322 * @see #getIn() 323 */ 324 Message getOut(); 325 326 /** 327 * Returns the outbound request message as the given type 328 * <p/> 329 * <br/><b>Important:</b> If you want to change the current message, then use {@link #getIn()} instead as it will 330 * ensure headers etc. is kept and propagated when routing continues. Bottom line end users should rarely use 331 * this method. 332 * <p/> 333 * <br/>If you want to test whether an OUT message have been set or not, use the {@link #hasOut()} method. 334 * <p/> 335 * See also the class java doc for this {@link Exchange} for more details and this 336 * <a href="http://camel.apache.org/using-getin-or-getout-methods-on-exchange.html">FAQ entry</a>. 337 * 338 * @param type the given type 339 * @return the message as the given type or <tt>null</tt> if not possible to covert to given type 340 * @see #getIn(Class) 341 */ 342 <T> T getOut(Class<T> type); 343 344 /** 345 * Returns whether an OUT message has been set or not. 346 * 347 * @return <tt>true</tt> if an OUT message exists, <tt>false</tt> otherwise. 348 */ 349 boolean hasOut(); 350 351 /** 352 * Sets the outbound message 353 * 354 * @param out the outbound message 355 */ 356 void setOut(Message out); 357 358 /** 359 * Returns the exception associated with this exchange 360 * 361 * @return the exception (or null if no faults) 362 */ 363 Exception getException(); 364 365 /** 366 * Returns the exception associated with this exchange. 367 * <p/> 368 * Is used to get the caused exception that typically have been wrapped in some sort 369 * of Camel wrapper exception 370 * <p/> 371 * The strategy is to look in the exception hierarchy to find the first given cause that matches the type. 372 * Will start from the bottom (the real cause) and walk upwards. 373 * 374 * @param type the exception type 375 * @return the exception (or <tt>null</tt> if no caused exception matched) 376 */ 377 <T> T getException(Class<T> type); 378 379 /** 380 * Sets the exception associated with this exchange 381 * <p/> 382 * Camel will wrap {@link Throwable} into {@link Exception} type to 383 * accommodate for the {@link #getException()} method returning a plain {@link Exception} type. 384 * 385 * @param t the caused exception 386 */ 387 void setException(Throwable t); 388 389 /** 390 * Returns true if this exchange failed due to either an exception or fault 391 * 392 * @return true if this exchange failed due to either an exception or fault 393 * @see Exchange#getException() 394 * @see Message#setFault(boolean) 395 * @see Message#isFault() 396 */ 397 boolean isFailed(); 398 399 /** 400 * Returns true if this exchange is transacted 401 */ 402 boolean isTransacted(); 403 404 /** 405 * Returns true if this exchange is an external initiated redelivered message (such as a JMS broker). 406 * <p/> 407 * <b>Important: </b> It is not always possible to determine if the message is a redelivery 408 * or not, and therefore <tt>null</tt> is returned. Such an example would be a JDBC message. 409 * However JMS brokers provides details if a message is redelivered. 410 * 411 * @return <tt>true</tt> if redelivered, <tt>false</tt> if not, <tt>null</tt> if not able to determine 412 */ 413 Boolean isExternalRedelivered(); 414 415 /** 416 * Returns true if this exchange is marked for rollback 417 */ 418 boolean isRollbackOnly(); 419 420 /** 421 * Returns the container so that a processor can resolve endpoints from URIs 422 * 423 * @return the container which owns this exchange 424 */ 425 CamelContext getContext(); 426 427 /** 428 * Creates a copy of the current message exchange so that it can be 429 * forwarded to another destination 430 */ 431 Exchange copy(); 432 433 /** 434 * Returns the endpoint which originated this message exchange if a consumer on an endpoint 435 * created the message exchange, otherwise this property will be <tt>null</tt> 436 */ 437 Endpoint getFromEndpoint(); 438 439 /** 440 * Sets the endpoint which originated this message exchange. This method 441 * should typically only be called by {@link org.apache.camel.Endpoint} implementations 442 * 443 * @param fromEndpoint the endpoint which is originating this message exchange 444 */ 445 void setFromEndpoint(Endpoint fromEndpoint); 446 447 /** 448 * Returns the route id which originated this message exchange if a route consumer on an endpoint 449 * created the message exchange, otherwise this property will be <tt>null</tt> 450 */ 451 String getFromRouteId(); 452 453 /** 454 * Sets the route id which originated this message exchange. This method 455 * should typically only be called by the internal framework. 456 * 457 * @param fromRouteId the from route id 458 */ 459 void setFromRouteId(String fromRouteId); 460 461 /** 462 * Returns the unit of work that this exchange belongs to; which may map to 463 * zero, one or more physical transactions 464 */ 465 UnitOfWork getUnitOfWork(); 466 467 /** 468 * Sets the unit of work that this exchange belongs to; which may map to 469 * zero, one or more physical transactions 470 */ 471 void setUnitOfWork(UnitOfWork unitOfWork); 472 473 /** 474 * Returns the exchange id (unique) 475 */ 476 String getExchangeId(); 477 478 /** 479 * Set the exchange id 480 */ 481 void setExchangeId(String id); 482 483 /** 484 * Adds a {@link org.apache.camel.spi.Synchronization} to be invoked as callback when 485 * this exchange is completed. 486 * 487 * @param onCompletion the callback to invoke on completion of this exchange 488 */ 489 void addOnCompletion(Synchronization onCompletion); 490 491 /** 492 * Checks if the passed {@link org.apache.camel.spi.Synchronization} instance is 493 * already contained on this exchange. 494 * 495 * @param onCompletion the callback instance that is being checked for 496 * @return <tt>true</tt>, if callback instance is already contained on this exchange, else <tt>false</tt> 497 */ 498 boolean containsOnCompletion(Synchronization onCompletion); 499 500 /** 501 * Handover all the on completions from this exchange to the target exchange. 502 * 503 * @param target the target exchange 504 */ 505 void handoverCompletions(Exchange target); 506 507 /** 508 * Handover all the on completions from this exchange 509 * 510 * @return the on completions 511 */ 512 List<Synchronization> handoverCompletions(); 513 514 }