JMS from Synchronous to Asynchronous

Question

I was able to create a Synchronous service bus using the JMS, but I was not able to turn it to Asynchronous. I'm trying to post a request to a service asynchronously, so if the service is down, I want the JMS queue keeps the request message and when the service starts up it delivers the message to the service and get back the response.

here is my code

<camelContext xmlns="http://camel.apache.org/schema/spring">
        <route >
            <from id ="server" uri="jetty:http://0.0.0.0:9500/rsb/toService?matchOnUriPrefix=true&amp;enableMultipartFilter=false&amp;disableStreamCache=false"/>
            <wireTap uri="log:test?level=INFO"><body><simple>Enter JMS test route and sending message to queue</simple></body></wireTap>
            <!--<to uri="direct:queue"/>-->
            <to uri="jms://testqueue?requestTimeout=360000&amp;replyTo=bar&amp;replyToDeliveryPersistent=true&amp;exchangePattern=InOut&amp;acknowledgementModeName=AUTO_ACKNOWLEDGE"/>
        </route>
        <route id="testqueuelistener" streamCache="true">
            <from uri="jms://testqueue?replyToDeliveryPersistent=true&amp;replyTo=bar" />
            <wireTap uri="log:test?level=INFO"><body><simple>Message recieved from queue: ${body}</simple></body></wireTap>             
            <to uri="http://localhost:18402/Home/addUser?bridgeEndpoint=true&amp;throwExceptionOnFailure=false"/>
            <to uri="jms:service"/> 
        </route>
        <route >
            <from uri="jms:service"/>
            <transform>
                <simple>${body}</simple>
            </transform>
        </route>
    </camelContext>

What is the actual issue you meet (what happens when you try this)? Also, which JMS implementation do you use, and how is it configured? — Cyäegha
jms configuration <osgi:reference id="jmsConnectionPool" interface="javax.jms.ConnectionFactory"/> <bean id="jms" class="org.apache.camel.component.jms.JmsComponent"> <property name="connectionFactory" ref="jmsConnectionPool" /> </bean> my actual issue is if the service "localhost:18402/Home/addUser"; is down -not running- I got Error 404 Not Found Problem accessing /rsb/toService. Reason: Not Found I was hoping to keep the request message in the queue "testqueue" until the service starts up and then receive the message in the queue. — Joey

Cyäegha Cyäegha · Accepted Answer · 2016-06-16T18:59:16

The issue is that you are accessing the JMS queue without using a transaction - so as soon as you get the message, it's gone from the queue. You need to use a transaction and only commit (or rollback) the message consumption after you've finished processing it.

The relevant Enterprise Integration Pattern is the transactional client. The JMS component documentation also provides some information about transaction. Finally, chapter 9 of Camel in Action (chapter 12 for the second edition) is dedicated to transactions (and I can't recommend it enough!).

You need to:

Obtain a JMS transaction manager (which transaction manager you use may depend on your specific use case)
Configure the Camel JMS component to use the transaction manager
Use a transaction policy to configure the transactional behavior of your route (or just mark the route as transacted, and use the default policy)

The configuration can look something like:

<!-- Import JMS connection factory -->
<osgi:reference id="jmsConnectionPool" interface="javax.jms.ConnectionFactory" />
<!-- We create a Spring JmsTransactionManager (our transaction manager could also be an
imported OSGi service, like we do for the connection factory; for example an XA transaction
manager) -->
<bean id="jmsTxManager" class="org.springframework.jms.connection.JmsTransactionManager">
    <property name="connectionFactory" ref="jmsConnectionPool"/>
</bean>
<!-- We configure the JMS component to use the transaction manager-->
<bean id="jms" class="org.apache.camel.component.jms.JmsComponent">
    <property name="connectionFactory" ref="jmsConnectionPool" />
    <property name="transacted" value="true"/>
    <property name="transactionManager" ref="jmsTxManager"/>
</bean>

<!-- Here's an example of a transaction policy -->
<bean id="requiresNew" class="org.apache.camel.spring.spi.SpringTransactionPolicy">
    <property name="transactionManager" ref="jtaTransactionManager"/>
    <property name="propagationBehaviorName" value="PROPAGATION_REQUIRES_NEW"/>
</bean>

Here's a transacted route:

<route id="myRoute">
    <from uri="jms://..." />
    <transacted/>
    ...
</route>

And a route can use a specific transaction policy if we want:

<route id="myRoute">
    <from uri="jms://..." />
    <transacted ref="requiresNew" />
    ...
</route>

JMS from Synchronous to Asynchronous

1 Answers