我很困惑Camel在使用邮件队列时如何自动形成邮件和相关标识符。
例如，我有以下路线的两项服务
<route id="cxfToJMSRoute">
<from uri="cxf:bean:endpoint" />
<convertBodyTo type="String" />
<log message="..." />
<log message="In message: ${in.body}" />
<log message="In JMSMessageID: ${in.header.JMSMessageID}" />
<log message="In JMSCorrelationID: ${in.header.JMSCorrelationID}" />
<log message="Out message: ${out.body}" />
<log message="Out JMSMessageID: ${out.header.JMSMessageID}" />
<log message="Out JMSCorrelationID: ${out.header.JMSCorrelationID}" />
<log message="Invoking service A by sending InOut message to api queue" />
<to uri="activemq:queue:api?replyTo=result&replyToType=Exclusive"
pattern="InOut" />
<log message="..." />
<log message="Got message from Service A" />
<log message="In message: ${in.body}" />
<log message="In JMSMessageID: ${in.header.JMSMessageID}" />
<log message="In JMSCorrelationID: ${in.header.JMSCorrelationID}" />
<log message="Out message: ${out.body}" />
<log message="Out JMSMessageID: ${out.header.JMSMessageID}" />
<log message="Out JMSCorrelationID: ${out.header.JMSCorrelationID}" />
<!-- Correlation ID? -->
<pollEnrich>
<constant>activemq:queue:reply</constant>
</pollEnrich>
<log message="..." />
<log message="Got message from Service B" />
<log message="In message: ${in.body}" />
<log message="In JMSMessageID: ${in.header.JMSMessageID}" />
<log message="In JMSCorrelationID: ${in.header.JMSCorrelationID}" />
<log message="Out message: ${out.body}" />
<log message="Out JMSMessageID: ${out.header.JMSMessageID}" />
<log message="Out JMSCorrelationID: ${out.header.JMSCorrelationID}" />
<transform>
<simple>${in.body}</simple>
</transform>
<log message="After transform:" />
<log message="In message: ${in.body}" />
<log message="In JMSMessageID: ${in.header.JMSMessageID}" />
<log message="In JMSCorrelationID: ${in.header.JMSCorrelationID}" />
<log message="Out message: ${out.body}" />
<log message="Out JMSMessageID: ${out.header.JMSMessageID}" />
<log message="Out JMSCorrelationID: ${out.header.JMSCorrelationID}" />
<log message="..." />
</route>
-
<route id="apiToServiceARoute">
<from uri="activemq:queue:api"/>
<log message="..." />
<log message="In message: ${in.body}" />
<log message="In JMSMessageID: ${in.header.JMSMessageID}" />
<log message="In JMSCorrelationID: ${in.header.JMSCorrelationID}" />
<log message="Out message: ${out.body}" />
<log message="Out JMSMessageID: ${out.header.JMSMessageID}" />
<log message="Out JMSCorrelationID: ${out.header.JMSCorrelationID}" />
<log message="Mocking service B by sending InOnly message to reply queue" />
<to uri="activemq:queue:reply?exchangePattern=InOnly" pattern="InOnly" />
<transform>
<simple>Delegated</simple>
</transform>
<log message="..." />
<log message="After transform:" />
<log message="In message: ${in.body}" />
<log message="In JMSMessageID: ${in.header.JMSMessageID}" />
<log message="In JMSCorrelationID: ${in.header.JMSCorrelationID}" />
<log message="Out message: ${out.body}" />
<log message="Out JMSMessageID: ${out.header.JMSMessageID}" />
<log message="Out JMSCorrelationID: ${out.header.JMSCorrelationID}" />
<log message="..." />
</route>
以下是根据日志消息的观察结果
OUT消息始终为空。 Camel默认情况下是否总是使用IN，直到OUT被某个处理器创建为异常？JMSMessageID和JMSCorrelationID似乎没有任何联系。 Camel 仅使用JMSCorrelationID来关联消息吗？JMSCorrelationID消息发送到请求源自的另一个队列（回复）时保留InOnly。这是可取的，但它实际上是如何做到的？保留JMSCorrelationID？以下是两个示例路线的实际日志
2017-12-03 12:16:06.197 INFO 13780 --- [qtp335580595-36] cxfToJMSRoute : ...
2017-12-03 12:16:06.197 INFO 13780 --- [qtp335580595-36] cxfToJMSRoute : In message: testi2
2017-12-03 12:16:06.198 INFO 13780 --- [qtp335580595-36] cxfToJMSRoute : In JMSMessageID:
2017-12-03 12:16:06.198 INFO 13780 --- [qtp335580595-36] cxfToJMSRoute : In JMSCorrelationID:
2017-12-03 12:16:06.198 INFO 13780 --- [qtp335580595-36] cxfToJMSRoute : Out message:
2017-12-03 12:16:06.198 INFO 13780 --- [qtp335580595-36] cxfToJMSRoute : Out JMSMessageID:
2017-12-03 12:16:06.198 INFO 13780 --- [qtp335580595-36] cxfToJMSRoute : Out JMSCorrelationID:
2017-12-03 12:16:06.198 INFO 13780 --- [qtp335580595-36] cxfToJMSRoute : Invoking service A by sending InOut message to api queue
2017-12-03 12:16:06.569 INFO 13780 --- [Manager[result]] cxfToJMSRoute : ...
2017-12-03 12:16:06.570 INFO 13780 --- [Manager[result]] cxfToJMSRoute : Got message from Service A
2017-12-03 12:16:06.570 INFO 13780 --- [Manager[result]] cxfToJMSRoute : In message: Delegated
2017-12-03 12:16:06.582 INFO 13780 --- [Manager[result]] cxfToJMSRoute : In JMSMessageID: ID:DESKTOP-LI5P50P-54036-1512296151920-1:1:1:1:1
2017-12-03 12:16:06.582 INFO 13780 --- [Manager[result]] cxfToJMSRoute : In JMSCorrelationID: Camel-ID-DESKTOP-LI5P50P-1512296077166-0-2
2017-12-03 12:16:06.582 INFO 13780 --- [Manager[result]] cxfToJMSRoute : Out message:
2017-12-03 12:16:06.582 INFO 13780 --- [Manager[result]] cxfToJMSRoute : Out JMSMessageID:
2017-12-03 12:16:06.583 INFO 13780 --- [Manager[result]] cxfToJMSRoute : Out JMSCorrelationID:
2017-12-03 12:16:06.596 INFO 13780 --- [Manager[result]] cxfToJMSRoute : ...
2017-12-03 12:16:06.596 INFO 13780 --- [Manager[result]] cxfToJMSRoute : Got message from Service B
2017-12-03 12:16:06.596 INFO 13780 --- [Manager[result]] cxfToJMSRoute : In message: testi2
2017-12-03 12:16:06.597 INFO 13780 --- [Manager[result]] cxfToJMSRoute : In JMSMessageID: ID:DESKTOP-LI5P50P-54036-1512296151920-3:1:1:1:1
2017-12-03 12:16:06.597 INFO 13780 --- [Manager[result]] cxfToJMSRoute : In JMSCorrelationID: Camel-ID-DESKTOP-LI5P50P-1512296077166-0-2
2017-12-03 12:16:06.597 INFO 13780 --- [Manager[result]] cxfToJMSRoute : Out message:
2017-12-03 12:16:06.597 INFO 13780 --- [Manager[result]] cxfToJMSRoute : Out JMSMessageID:
2017-12-03 12:16:06.597 INFO 13780 --- [Manager[result]] cxfToJMSRoute : Out JMSCorrelationID:
2017-12-03 12:16:06.598 INFO 13780 --- [Manager[result]] cxfToJMSRoute : After transform:
2017-12-03 12:16:06.598 INFO 13780 --- [Manager[result]] cxfToJMSRoute : In message: testi2
2017-12-03 12:16:06.598 INFO 13780 --- [Manager[result]] cxfToJMSRoute : In JMSMessageID: ID:DESKTOP-LI5P50P-54036-1512296151920-3:1:1:1:1
2017-12-03 12:16:06.598 INFO 13780 --- [Manager[result]] cxfToJMSRoute : In JMSCorrelationID: Camel-ID-DESKTOP-LI5P50P-1512296077166-0-2
2017-12-03 12:16:06.598 INFO 13780 --- [Manager[result]] cxfToJMSRoute : Out message:
2017-12-03 12:16:06.598 INFO 13780 --- [Manager[result]] cxfToJMSRoute : Out JMSMessageID:
2017-12-03 12:16:06.598 INFO 13780 --- [Manager[result]] cxfToJMSRoute : Out JMSCorrelationID:
2017-12-03 12:16:06.598 INFO 13780 --- [Manager[result]] cxfToJMSRoute : ...
-
2017-12-03 12:16:06.528 INFO 16972 --- [msConsumer[api]] apiToServiceARoute : ...
2017-12-03 12:16:06.531 INFO 16972 --- [msConsumer[api]] apiToServiceARoute : In message: testi2
2017-12-03 12:16:06.534 INFO 16972 --- [msConsumer[api]] apiToServiceARoute : In JMSMessageID: ID:DESKTOP-LI5P50P-54046-1512296166309-1:1:2:1:1
2017-12-03 12:16:06.534 INFO 16972 --- [msConsumer[api]] apiToServiceARoute : In JMSCorrelationID: Camel-ID-DESKTOP-LI5P50P-1512296077166-0-2
2017-12-03 12:16:06.534 INFO 16972 --- [msConsumer[api]] apiToServiceARoute : Out message:
2017-12-03 12:16:06.535 INFO 16972 --- [msConsumer[api]] apiToServiceARoute : Out JMSMessageID:
2017-12-03 12:16:06.535 INFO 16972 --- [msConsumer[api]] apiToServiceARoute : Out JMSCorrelationID:
2017-12-03 12:16:06.535 INFO 16972 --- [msConsumer[api]] apiToServiceARoute : Mocking service B by sending InOnly message to reply queue
2017-12-03 12:16:06.558 INFO 16972 --- [msConsumer[api]] apiToServiceARoute : ...
2017-12-03 12:16:06.558 INFO 16972 --- [msConsumer[api]] apiToServiceARoute : After transform:
2017-12-03 12:16:06.558 INFO 16972 --- [msConsumer[api]] apiToServiceARoute : In message: Delegated
2017-12-03 12:16:06.558 INFO 16972 --- [msConsumer[api]] apiToServiceARoute : In JMSMessageID: ID:DESKTOP-LI5P50P-54046-1512296166309-1:1:2:1:1
2017-12-03 12:16:06.559 INFO 16972 --- [msConsumer[api]] apiToServiceARoute : In JMSCorrelationID: Camel-ID-DESKTOP-LI5P50P-1512296077166-0-2
2017-12-03 12:16:06.559 INFO 16972 --- [msConsumer[api]] apiToServiceARoute : Out message:
2017-12-03 12:16:06.559 INFO 16972 --- [msConsumer[api]] apiToServiceARoute : Out JMSMessageID:
2017-12-03 12:16:06.559 INFO 16972 --- [msConsumer[api]] apiToServiceARoute : Out JMSCorrelationID:
2017-12-03 12:16:06.559 INFO 16972 --- [msConsumer[api]] apiToServiceARoute : ...
答案 0 :(得分：4)
OUT消息始终为空。默认情况下，Camel是否始终使用IN，直到某些处理器明确创建OUT为止？
是。克隆整个org.apache.camel.Message非常昂贵。在第一次调用OUT
Exchange#getOut
请参阅Apache Camel: Message exchange patterns and the Exchange object
JMSMessageID和JMSCorrelationID似乎没有任何联系。 Camel仅使用JMSCorrelationID来关联消息吗？
不完全是。 camel-jms（以及正在扩展它的camel-activemq）组件标头JMSCorrelationID到标头CamelCorrelationId。
pollEnrich中的相关性再次与CamelCorrelationId合作，而camel-jms将此标头转换为消息选择器JMSCorrelationID=CamelCorrelationId。
是的，在camel-jms（和继承的组件）端点与exchangePattern=InOnly之间进行通信时，将在标头JMSCorrelationID上有效地进行关联。
请参阅Apache Camel: Correlation Identifier
- 当将InOnly消息发送到请求源自的另一个队列（回复）时，Camel设法保留
的具体规则是什么？JMSCorrelationID。这是可取的，但它实际上是如何做到的？保留JMSCorrelationID？
使用JMSCorrelationID时，Camel对exchangePattern=InOnly进行了无转换。
在输入路线上，Camel从输入javax.jms.Message获取相关ID并将其保存到org.apache.camel.Message#headers.JMSCorrelationId。
在输出路线上，Camel从org.apache.camel.Message#headers.JMSCorrelationId获取相关ID并将其设置为javax.jms.Message.setJMSCorrelationID()。
注意：我不是Apache Camel的开发人员。我在这个答案中写的每个字都是基于使用这个框架时的用户体验。答案可能存在细微的差异。