Camel in/out 消息和相关 ID 混淆

【问题标题】：Camel in/out messages and correlation ID confusionCamel in/out 消息和相关 ID 混淆
【发布时间】：2018-05-16 23:44:15
【问题描述】：

我很困惑 Camel 在使用消息队列时如何自动形成消息和相关标识符。

例如，我有两个具有以下路线的服务

<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&amp;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>

这是我根据日志消息的观察结果

  1. OUT 消息始终为空。 Camel 是否总是默认使用IN，直到OUT 被某些处理器明确创建？
  2. JMSMessageID 和 JMSCorrelationID 似乎没有任何联系。 Camel 是否仅使用JMSCorrelationID 来关联消息？
  3. Camel 在将InOnly 消息发送到请求来源的另一个队列（回复）时设法保留JMSCorrelationID。这是可取的，但它实际上是如何做到的呢？保留JMSCorrelationID的具体规则是什么？

这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                       : ...

【问题讨论】：

  • 它几乎总是基于correlationId。在 IBM MQ 和 RabbitMQ 中也是如此。

标签： apache-camel jms activemq integration messaging


【解决方案1】：
  1. OUT 消息始终为空。 Camel 是否总是默认使用IN，直到OUT 由某个处理器显式创建？

是的。克隆整个org.apache.camel.Message 真的很贵。 OUT 是在第一次调用Exchange#getOut 期间按需创建的

见Apache Camel: Message exchange patterns and the Exchange object

  1. JMSMessageID 和 JMSCorrelationID 似乎没有任何联系。 Camel 是否仅使用 JMSCorrelationID 来关联消息？

不完全是。 camel-jms（以及扩展它的camel-activemq）组件将标题JMSCorrelationID 复制到标题CamelCorrelationId。

pollEnrich 中的相关性再次与CamelCorrelationId 一起使用，camel-jms 将此标头转换为消息选择器JMSCorrelationID=CamelCorrelationId。

所以是的，在camel-jms（和继承的组件）端点和exchangePattern=InOnly 之间进行通信时，将在标头JMSCorrelationID 上有效地完成相关性。

见Apache Camel: Correlation Identifier

  1. Camel 在将 InOnly 消息发送到请求来源的另一个队列（回复）时设法保留 JMSCorrelationID。这是可取的，但它实际上是如何做到的呢？保留JMSCorrelationID的具体规则是什么？

Camel 在使用exchangePattern=InOnly 时no 转换JMSCorrelationID。

在输入路由上，Camel 从输入 javax.jms.Message 获取相关 id 并将其保存到 org.apache.camel.Message#headers.JMSCorrelationId。

在输出路由上，Camel 从 org.apache.camel.Message#headers.JMSCorrelationId 获取关联 id 并将其设置为 javax.jms.Message.setJMSCorrelationID()。

注意：我不是 Apache Camel 的开发者。我在这个答案中写的每一个字都是基于使用这个框架时的用户体验。答案可能存在细微差异。

【讨论】：

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