What is the cleanest way to listen to JMS from inside a Spring-batch step? - activemq

Question

Spring batch documentation recommends using the JmsItemReader, which is a wrapper around the JMSTemplate. However, I have discovered that the JMSTemplate has some issues - see http://activemq.apache.org/jmstemplate-gotchas.html .
This post came to my attention only because the queue was appearing to disappear before I could actually read the data of of it. The opportunity to miss messages seems like a fairly significant issue to me.

Answer 1

For consumers atleast try using DefaultMessageListenerContainer coupled with a SingleConnectionFactory or any such connection factory , it not need a scheduler to wake them up.there are log of examples explaining this , this one is really good in explaining stuff
http://bsnyderblog.blogspot.com/2010/05/tuning-jms-message-consumption-in.html

Answer 2

Here is the solution I ended up with. Since the query was about the "cleanest" way to listen to JMS from within a spring-batch step, I'm going to leave the question open for a while longer just in case there's a better way.
If someone can figure out why the code isn't formatting correctly, please let me know how to fix it.
1. In the a job listener, implement queue setup and teardown inside the beforeJob and afterJob events, respectively:
public void beforeJob(JobExecution jobExecution) {
try {
jobParameters = jobExecution.getJobParameters();
readerConnection = connectionFactory.createConnection();
readerConnection.start();
} catch (JMSException ex) {
// handle the exception as appropriate
}
}
public void afterJob(JobExecution jobExecution) {
try {
readerConnection.close();
} catch (JMSException e) {
// handle the exception as appropriate
}
}
2. In the reader, implement the StepListener and beforeStep / afterStep methods.
public void beforeStep(StepExecution stepExecution) {
this.stepExecution = stepExecution;
this.setJobExecution(stepExecution.getJobExecution());
try {
this.connection = jmsJobExecutionListener.getReaderConnection();
this.jmsSession = connection.createSession(false, Session.AUTO_ACKNOWLEDGE);
this.messageConsumer = jmsSession.createConsumer(jmsJobExecutionListener.getQueue());
}
catch (JMSException ex)
{
// handle the exception as appropriate
}
}
public ExitStatus afterStep(StepExecution stepExecution) {
try {
messageConsumer.close();
jmsSession.close();
} catch (JMSException e) {
// handle the exception as appropriate
}
return stepExecution.getExitStatus();
}
3. Implement the read() method:
public TreeModel<SelectedDataElementNode> read() throws Exception,
UnexpectedInputException, ParseException,
NonTransientResourceException {
Object result = null;
logger.debug("Attempting to receive message on connection: ", connection.toString());
ObjectMessage msg = (ObjectMessage) messageConsumer.receive();
logger.debug("Received: {}", msg.toString());
result = msg.getObject();
return result;
}
4. Add the listeners to the Spring Batch context as appropriate:
<batch:job id="doStuff">
<batch:listeners>
<batch:listener ref="jmsJobExecutionListener" />
</batch:listeners>
... snip ...
<batch:step id="step0003-do-stuff">
<batch:tasklet transaction-manager="jtaTransactionManager"
start-limit="100">
<batch:chunk reader="selectedDataJmsReader" writer="someWriter"
commit-interval="1" />
</batch:tasklet>
<batch:listeners>
<batch:listener ref="selectedDataJmsReader" />
</batch:listeners>
</batch:step>
</batch:job>