About using Camel to send and receive messages and JMSReplyTo - 6.3

Talend ESB Mediation Developer Guide

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6.3
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Talend Data Fabric
Talend Data Services Platform
Talend ESB
Talend MDM Platform
Talend Open Studio for ESB
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task
Design and Development
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Talend ESB

The JMS component is complex and you have to pay close attention to how it works in some cases. So this is a short summary of some of the areas/pitfalls to look for.

When Camel sends a message using its JMSProducer, it checks the following conditions:

  • The message exchange pattern,

  • Whether a JMSReplyTo was set in the endpoint or in the message headers,

  • Whether any of the following options have been set on the JMS endpoint: disableReplyTo, preserveMessageQos, explicitQosEnabled.

All this can be complex to understand and configure to support your use case.

JmsProducer

The JmsProducer behaves as follows, depending on configuration:

Exchange Pattern

Other options

Description

InOut

-

Camel will expect a reply, set a temporary JMSReplyTo, and after sending the message, it will start to listen for the reply message on the temporary queue.

InOut

JMSReplyTo is set

Camel will expect a reply and, after sending the message, it will start to listen for the reply message on the specified JMSReplyTo queue.

InOnly

-

Camel will send the message and not expect a reply.

InOnly

JMSReplyTo is set

By default, Camel discards the JMSReplyTo destination and clears the JMSReplyTo header before sending the message. Camel then sends the message and does not expect a reply. Camel logs this in the log at DEBUG level. You can use preserveMessageQuo=true to instruct Camel to keep the JMSReplyTo. In all situations the JmsProducer does not expect any reply and thus continue after sending the message.

JmsConsumer

The JmsConsumer behaves as follows, depending on configuration:

Exchange Pattern

Other options

Description

InOut

-

Camel will send the reply back to the JMSReplyTo queue.

InOnly

-

Camel will not send a reply back, as the pattern is InOnly.

-

disableReplyTo=true

This option suppresses replies.

Thus, pay attention to the message exchange pattern set on your exchanges.

If you send a message to a JMS destination in the middle of your route you can specify the exchange pattern to use, see more at Request Reply. This is useful if you want to send an InOnly message to a JMS topic:

from("activemq:queue:in")
   .to("bean:validateOrder")
   .to(ExchangePattern.InOnly, "activemq:topic:order")
   .to("bean:handleOrder");