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 String INTERCEPT_SEND_TO_ENDPOINT_WHEN_MATCHED = "CamelInterceptSendToEndpointWhenMatched"; 141 142 String LANGUAGE_SCRIPT = "CamelLanguageScript"; 143 String LOG_DEBUG_BODY_MAX_CHARS = "CamelLogDebugBodyMaxChars"; 144 String LOG_DEBUG_BODY_STREAMS = "CamelLogDebugStreams"; 145 String LOOP_INDEX = "CamelLoopIndex"; 146 String LOOP_SIZE = "CamelLoopSize"; 147 148 String MAXIMUM_CACHE_POOL_SIZE = "CamelMaximumCachePoolSize"; 149 String MAXIMUM_ENDPOINT_CACHE_SIZE = "CamelMaximumEndpointCacheSize"; 150 String MULTICAST_INDEX = "CamelMulticastIndex"; 151 String MULTICAST_COMPLETE = "CamelMulticastComplete"; 152 153 String NOTIFY_EVENT = "CamelNotifyEvent"; 154 155 String ON_COMPLETION = "CamelOnCompletion"; 156 157 String PARENT_UNIT_OF_WORK = "CamelParentUnitOfWork"; 158 159 String RECEIVED_TIMESTAMP = "CamelReceivedTimestamp"; 160 String REDELIVERED = "CamelRedelivered"; 161 String REDELIVERY_COUNTER = "CamelRedeliveryCounter"; 162 String REDELIVERY_MAX_COUNTER = "CamelRedeliveryMaxCounter"; 163 String REDELIVERY_EXHAUSTED = "CamelRedeliveryExhausted"; 164 String REDELIVERY_DELAY = "CamelRedeliveryDelay"; 165 String ROLLBACK_ONLY = "CamelRollbackOnly"; 166 String ROLLBACK_ONLY_LAST = "CamelRollbackOnlyLast"; 167 String ROUTE_STOP = "CamelRouteStop"; 168 169 String SOAP_ACTION = "CamelSoapAction"; 170 String SKIP_GZIP_ENCODING = "CamelSkipGzipEncoding"; 171 String SLIP_ENDPOINT = "CamelSlipEndpoint"; 172 String SPLIT_INDEX = "CamelSplitIndex"; 173 String SPLIT_COMPLETE = "CamelSplitComplete"; 174 String SPLIT_SIZE = "CamelSplitSize"; 175 176 String TIMER_COUNTER = "CamelTimerCounter"; 177 String TIMER_FIRED_TIME = "CamelTimerFiredTime"; 178 String TIMER_NAME = "CamelTimerName"; 179 String TIMER_PERIOD = "CamelTimerPeriod"; 180 String TIMER_TIME = "CamelTimerTime"; 181 String TO_ENDPOINT = "CamelToEndpoint"; 182 String TRACE_EVENT = "CamelTraceEvent"; 183 String TRACE_EVENT_NODE_ID = "CamelTraceEventNodeId"; 184 String TRACE_EVENT_TIMESTAMP = "CamelTraceEventTimestamp"; 185 String TRACE_EVENT_EXCHANGE = "CamelTraceEventExchange"; 186 String TRANSFER_ENCODING = "Transfer-Encoding"; 187 188 String UNIT_OF_WORK_EXHAUSTED = "CamelUnitOfWorkExhausted"; 189 String UNIT_OF_WORK_PROCESS_SYNC = "CamelUnitOfWorkProcessSync"; 190 191 String XSLT_FILE_NAME = "CamelXsltFileName"; 192 193 /** 194 * Returns the {@link ExchangePattern} (MEP) of this exchange. 195 * 196 * @return the message exchange pattern of this exchange 197 */ 198 ExchangePattern getPattern(); 199 200 /** 201 * Allows the {@link ExchangePattern} (MEP) of this exchange to be customized. 202 * 203 * This typically won't be required as an exchange can be created with a specific MEP 204 * by calling {@link Endpoint#createExchange(ExchangePattern)} but it is here just in case 205 * it is needed. 206 * 207 * @param pattern the pattern 208 */ 209 void setPattern(ExchangePattern pattern); 210 211 /** 212 * Returns a property associated with this exchange by name 213 * 214 * @param name the name of the property 215 * @return the value of the given property or <tt>null</tt> if there is no property for 216 * the given name 217 */ 218 Object getProperty(String name); 219 220 /** 221 * Returns a property associated with this exchange by name 222 * 223 * @param name the name of the property 224 * @param defaultValue the default value to return if property was absent 225 * @return the value of the given property or <tt>defaultValue</tt> if there is no 226 * property for the given name 227 */ 228 Object getProperty(String name, Object defaultValue); 229 230 /** 231 * Returns a property associated with this exchange by name and specifying 232 * the type required 233 * 234 * @param name the name of the property 235 * @param type the type of the property 236 * @return the value of the given property or <tt>null</tt> if there is no property for 237 * the given name or <tt>null</tt> if it cannot be converted to the given type 238 */ 239 <T> T getProperty(String name, Class<T> type); 240 241 /** 242 * Returns a property associated with this exchange by name and specifying 243 * the type required 244 * 245 * @param name the name of the property 246 * @param defaultValue the default value to return if property was absent 247 * @param type the type of the property 248 * @return the value of the given property or <tt>defaultValue</tt> if there is no property for 249 * the given name or <tt>null</tt> if it cannot be converted to the given type 250 */ 251 <T> T getProperty(String name, Object defaultValue, Class<T> type); 252 253 /** 254 * Sets a property on the exchange 255 * 256 * @param name of the property 257 * @param value to associate with the name 258 */ 259 void setProperty(String name, Object value); 260 261 /** 262 * Removes the given property on the exchange 263 * 264 * @param name of the property 265 * @return the old value of the property 266 */ 267 Object removeProperty(String name); 268 269 /** 270 * Returns all of the properties associated with the exchange 271 * 272 * @return all the headers in a Map 273 */ 274 Map<String, Object> getProperties(); 275 276 /** 277 * Returns whether any properties has been set 278 * 279 * @return <tt>true</tt> if any properties has been set 280 */ 281 boolean hasProperties(); 282 283 /** 284 * Returns the inbound request message 285 * 286 * @return the message 287 */ 288 Message getIn(); 289 290 /** 291 * Returns the inbound request message as the given type 292 * 293 * @param type the given type 294 * @return the message as the given type or <tt>null</tt> if not possible to covert to given type 295 */ 296 <T> T getIn(Class<T> type); 297 298 /** 299 * Sets the inbound message instance 300 * 301 * @param in the inbound message 302 */ 303 void setIn(Message in); 304 305 /** 306 * Returns the outbound message, lazily creating one if one has not already 307 * been associated with this exchange. 308 * <p/> 309 * <br/><b>Important:</b> If you want to change the current message, then use {@link #getIn()} instead as it will 310 * ensure headers etc. is kept and propagated when routing continues. Bottom line end users should rarely use 311 * this method. 312 * <p/> 313 * <br/>If you want to test whether an OUT message have been set or not, use the {@link #hasOut()} method. 314 * <p/> 315 * See also the class java doc for this {@link Exchange} for more details and this 316 * <a href="http://camel.apache.org/using-getin-or-getout-methods-on-exchange.html">FAQ entry</a>. 317 * 318 * @return the response 319 * @see #getIn() 320 */ 321 Message getOut(); 322 323 /** 324 * Returns the outbound request message as the given type 325 * <p/> 326 * <br/><b>Important:</b> If you want to change the current message, then use {@link #getIn()} instead as it will 327 * ensure headers etc. is kept and propagated when routing continues. Bottom line end users should rarely use 328 * this method. 329 * <p/> 330 * <br/>If you want to test whether an OUT message have been set or not, use the {@link #hasOut()} method. 331 * <p/> 332 * See also the class java doc for this {@link Exchange} for more details and this 333 * <a href="http://camel.apache.org/using-getin-or-getout-methods-on-exchange.html">FAQ entry</a>. 334 * 335 * @param type the given type 336 * @return the message as the given type or <tt>null</tt> if not possible to covert to given type 337 * @see #getIn(Class) 338 */ 339 <T> T getOut(Class<T> type); 340 341 /** 342 * Returns whether an OUT message has been set or not. 343 * 344 * @return <tt>true</tt> if an OUT message exists, <tt>false</tt> otherwise. 345 */ 346 boolean hasOut(); 347 348 /** 349 * Sets the outbound message 350 * 351 * @param out the outbound message 352 */ 353 void setOut(Message out); 354 355 /** 356 * Returns the exception associated with this exchange 357 * 358 * @return the exception (or null if no faults) 359 */ 360 Exception getException(); 361 362 /** 363 * Returns the exception associated with this exchange. 364 * <p/> 365 * Is used to get the caused exception that typically have been wrapped in some sort 366 * of Camel wrapper exception 367 * <p/> 368 * The strategy is to look in the exception hierarchy to find the first given cause that matches the type. 369 * Will start from the bottom (the real cause) and walk upwards. 370 * 371 * @param type the exception type 372 * @return the exception (or <tt>null</tt> if no caused exception matched) 373 */ 374 <T> T getException(Class<T> type); 375 376 /** 377 * Sets the exception associated with this exchange 378 * <p/> 379 * Camel will wrap {@link Throwable} into {@link Exception} type to 380 * accommodate for the {@link #getException()} method returning a plain {@link Exception} type. 381 * 382 * @param t the caused exception 383 */ 384 void setException(Throwable t); 385 386 /** 387 * Returns true if this exchange failed due to either an exception or fault 388 * 389 * @return true if this exchange failed due to either an exception or fault 390 * @see Exchange#getException() 391 * @see Message#setFault(boolean) 392 * @see Message#isFault() 393 */ 394 boolean isFailed(); 395 396 /** 397 * Returns true if this exchange is transacted 398 */ 399 boolean isTransacted(); 400 401 /** 402 * Returns true if this exchange is an external initiated redelivered message (such as a JMS broker). 403 * <p/> 404 * <b>Important: </b> It is not always possible to determine if the message is a redelivery 405 * or not, and therefore <tt>null</tt> is returned. Such an example would be a JDBC message. 406 * However JMS brokers provides details if a message is redelivered. 407 * 408 * @return <tt>true</tt> if redelivered, <tt>false</tt> if not, <tt>null</tt> if not able to determine 409 */ 410 Boolean isExternalRedelivered(); 411 412 /** 413 * Returns true if this exchange is marked for rollback 414 */ 415 boolean isRollbackOnly(); 416 417 /** 418 * Returns the container so that a processor can resolve endpoints from URIs 419 * 420 * @return the container which owns this exchange 421 */ 422 CamelContext getContext(); 423 424 /** 425 * Creates a copy of the current message exchange so that it can be 426 * forwarded to another destination 427 */ 428 Exchange copy(); 429 430 /** 431 * Returns the endpoint which originated this message exchange if a consumer on an endpoint 432 * created the message exchange, otherwise this property will be <tt>null</tt> 433 */ 434 Endpoint getFromEndpoint(); 435 436 /** 437 * Sets the endpoint which originated this message exchange. This method 438 * should typically only be called by {@link org.apache.camel.Endpoint} implementations 439 * 440 * @param fromEndpoint the endpoint which is originating this message exchange 441 */ 442 void setFromEndpoint(Endpoint fromEndpoint); 443 444 /** 445 * Returns the route id which originated this message exchange if a route consumer on an endpoint 446 * created the message exchange, otherwise this property will be <tt>null</tt> 447 */ 448 String getFromRouteId(); 449 450 /** 451 * Sets the route id which originated this message exchange. This method 452 * should typically only be called by the internal framework. 453 * 454 * @param fromRouteId the from route id 455 */ 456 void setFromRouteId(String fromRouteId); 457 458 /** 459 * Returns the unit of work that this exchange belongs to; which may map to 460 * zero, one or more physical transactions 461 */ 462 UnitOfWork getUnitOfWork(); 463 464 /** 465 * Sets the unit of work that this exchange belongs to; which may map to 466 * zero, one or more physical transactions 467 */ 468 void setUnitOfWork(UnitOfWork unitOfWork); 469 470 /** 471 * Returns the exchange id (unique) 472 */ 473 String getExchangeId(); 474 475 /** 476 * Set the exchange id 477 */ 478 void setExchangeId(String id); 479 480 /** 481 * Adds a {@link org.apache.camel.spi.Synchronization} to be invoked as callback when 482 * this exchange is completed. 483 * 484 * @param onCompletion the callback to invoke on completion of this exchange 485 */ 486 void addOnCompletion(Synchronization onCompletion); 487 488 /** 489 * Checks if the passed {@link org.apache.camel.spi.Synchronization} instance is 490 * already contained on this exchange. 491 * 492 * @param onCompletion the callback instance that is being checked for 493 * @return <tt>true</tt>, if callback instance is already contained on this exchange, else <tt>false</tt> 494 */ 495 boolean containsOnCompletion(Synchronization onCompletion); 496 497 /** 498 * Handover all the on completions from this exchange to the target exchange. 499 * 500 * @param target the target exchange 501 */ 502 void handoverCompletions(Exchange target); 503 504 /** 505 * Handover all the on completions from this exchange 506 * 507 * @return the on completions 508 */ 509 List<Synchronization> handoverCompletions(); 510 511 }