Question

我正在使用AMQP端点，并且在我的Mule应用程序的其他位置使用它（在此处提到一个警告[Possible bug with Mule AMQP transport 3.6.2 community）。

我正在尝试构建一个可靠的SMTP队列，但遇到了问题。

我假设如果SMTP连接器无法执行，则会抛出异常，因此通过将消息确认设置为MANUAL，并捕获SMTP异常并拒绝（并重新排列）异常策略中的消息，系统应该处理SMTP中断。

我的代码（略微简化）如下所示：

<amqp:connector name="connector.amqp.mule.default" ackMode="MANUAL" doc:name="AMQP Connector" validateConnections="true" host="${amiab-rabbitmq-hostname}" port="${amiab-rabbitmq-portnumber}" password="${amiab-rabbitmq-password}" username="${amiab-rabbitmq-username}"/>
<smtp:connector name="smtpConnector" contentType="text/html" doc:name="SMTPConnector"/>
<flow name="utility-smtpFlow">
  <amqp:inbound-endpoint exchangeName="AMQP.DEFAULT.EXCHANGE" queueName="utilitySMTP" exchangeType="direct"  responseTimeout="10000"  doc:name="AMQP-0-9" queueDurable="true"/>
    <logger message="Recevied SMTP Message from Queue" level="INFO" doc:name="Logger"/>
    <smtp:outbound-endpoint host="${smtp-hostname}" user="${smtp-username}" password="{smtp-password}" to="#[flowVars.smtpTo]" subject="Testing Message" responseTimeout="10000" doc:name="SMTP"/>
    <amqp:acknowledge-message doc:name="AMQP-0-9 Acknowledge Message"/>
    <catch-exception-strategy doc:name="Catch Exception Strategy">
        <logger message="SMTP Error, Requeuing" level="INFO" doc:name="Logger"/>
        <amqp:reject-message requeue="true" doc:name="AMQP-0-9 Reject Message"/>
    </catch-exception-strategy>

当我的SMTP连接器抛出异常时，正确启动了异常策略，但是AMQP会抛出错误，如下所示：

INFO  2015-06-18 16:32:22,383 [HTTP_Listener_AMIAB.worker.01] org.mule.transport.service.DefaultTransportServiceDescriptor: Loading default outbound transformer: org.mule.transport.amqp.internal.transformer.ObjectToAmqpMessage
INFO  2015-06-18 16:32:22,383 [HTTP_Listener_AMIAB.worker.01] org.mule.transport.service.DefaultTransportServiceDescriptor: Loading default response transformer: org.mule.transport.amqp.internal.transformer.ObjectToAmqpMessage
INFO  2015-06-18 16:32:22,387 [HTTP_Listener_AMIAB.worker.01] org.mule.lifecycle.AbstractLifecycleManager: Initialising: 'connector.amqp.mule.default.dispatcher.936721322'. Object is: Dispatcher
INFO  2015-06-18 16:32:22,389 [HTTP_Listener_AMIAB.worker.01] org.mule.lifecycle.AbstractLifecycleManager: Starting: 'connector.amqp.mule.default.dispatcher.936721322'. Object is: Dispatcher
INFO  2015-06-18 16:32:22,446 [[amiab-esb-utility].utility-smtpFlow.stage1.02] org.mule.api.processor.LoggerMessageProcessor: Recevied SMTP Message from Queue
INFO  2015-06-18 16:32:22,457 [[amiab-esb-utility].smtpConnector.dispatcher.01] org.mule.transport.service.DefaultTransportServiceDescriptor: Loading default outbound transformer: org.mule.transport.email.transformers.ObjectToMimeMessage
INFO  2015-06-18 16:32:22,481 [[amiab-esb-utility].smtpConnector.dispatcher.01] org.mule.lifecycle.AbstractLifecycleManager: Initialising: 'smtpConnector.dispatcher.404056326'. Object is: SmtpMessageDispatcher
ERROR 2015-06-18 16:32:22,568 [[amiab-esb-utility].smtpConnector.dispatcher.01] org.mule.exception.CatchMessagingExceptionStrategy: 
********************************************************************************
Message               : Unable to connect to mail transport.
Code                  : MULE_ERROR--2
--------------------------------------------------------------------------------
Exception stack is:
1. mail.lyrical.co.uk (java.net.UnknownHostException)
  java.net.AbstractPlainSocketImpl:178 (null)
2. Unknown SMTP host: mail.lyrical.co.uk (javax.mail.MessagingException)
  com.sun.mail.smtp.SMTPTransport:1704 (http://java.sun.com/j2ee/sdk_1.3/techdocs/api/javax/mail/MessagingException.html)
3. Unable to connect to mail transport. (org.mule.api.endpoint.EndpointException)
  org.mule.transport.email.SmtpMessageDispatcher:67 (http://www.mulesoft.org/docs/site/current3/apidocs/org/mule/api/endpoint/EndpointException.html)
--------------------------------------------------------------------------------
Root Exception stack trace:
java.net.UnknownHostException: mail.lyrical.co.uk
    at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:178)
    at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:172)
    at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:392)
    + 3 more (set debug level logging or '-Dmule.verbose.exceptions=true' for everything)
********************************************************************************

INFO  2015-06-17 15:25:47,190 [[amiab-esb-utility].smtpConnector.dispatcher.01] org.mule.api.processor.LoggerMessageProcessor: SMTP Error, Requeuing
WARN  2015-06-17 15:25:47,193 [amqpReceiver.01] org.mule.transport.amqp.internal.endpoint.receiver.MessageReceiverConsumer: Received shutdown signal for consumer tag: amq.ctag-NZ96mnj_oscnpJKAPy16ng, the message receiver will try to restart.
com.rabbitmq.client.ShutdownSignalException: channel error; protocol method: #method<channel.close>(reply-code=406, reply-text=PRECONDITION_FAILED - unknown delivery tag 1, class-id=60, method-id=90)
    at com.rabbitmq.client.impl.ChannelN.asyncShutdown(ChannelN.java:478) ~[?:?]
    at com.rabbitmq.client.impl.ChannelN.processAsync(ChannelN.java:315) ~[?:?]
    at com.rabbitmq.client.impl.AMQChannel.handleCompleteInboundCommand(AMQChannel.java:144) ~[?:?]
    at com.rabbitmq.client.impl.AMQChannel.handleFrame(AMQChannel.java:91) ~[?:?]
    at com.rabbitmq.client.impl.AMQConnection$MainLoop.run(AMQConnection.java:550) ~[?:?]
    at java.lang.Thread.run(Thread.java:745) [?:1.7.0_75]
INFO  2015-06-17 15:25:47,195 [amqpReceiver.01] org.mule.lifecycle.AbstractLifecycleManager: Stopping: 'null'. Object is: MultiChannelMessageSubReceiver
INFO  2015-06-17 15:25:47,195 [amqpReceiver.01] org.mule.transport.amqp.internal.endpoint.receiver.MultiChannelMessageSubReceiver: Connecting clusterizable message receiver
INFO  2015-06-17 15:25:47,195 [amqpReceiver.01] org.mule.lifecycle.AbstractLifecycleManager: Starting: 'null'. Object is: MultiChannelMessageSubReceiver
INFO  2015-06-17 15:25:47,196 [amqpReceiver.01] org.mule.transport.amqp.internal.endpoint.receiver.MultiChannelMessageSubReceiver: Starting clusterizable message receiver
INFO  2015-06-17 15:25:47,203 [amqpReceiver.01] org.mule.transport.amqp.internal.endpoint.receiver.MultiChannelMessageSubReceiver: Started subscription: amq.ctag-sCCRCnOWKyREyip26pSYDA on channel: AMQChannel(amqp://guest@127.0.0.1:5672/,3)

我是否遗漏了一些明显的东西，或者我误解了应该如何使用它？非常感谢有人能指出我正确的方向。

Answer 1

正如您在评论中指出的那样，smtp:outbound-endpoint是one-way端点，其调度操作在另一个线程中执行，因此它与流的执行并行发生。因此，amqp:acknowledge-message无论如何都会被调用，而与smtp:outbound-endpoint操作的成功或失败无关。

您可以通过在流上设置processingStrategy="synchronous"来解决此问题：这将强制在入站线程上执行所有端点交互。

无耻插件：Mule in Action第二版第11.2章对此进行了详细讨论。

Mule AMQP连接器尝试重新排队消息失败

1 个答案: