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< title > ActiveMQ JMS Queue Example< / title >
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< h1 > JMS Queue Example< / h1 >
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< p > This example shows you how to send and receive a message to a JMS Queue using ActiveMQ.< / p >
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< p > Queues are a standard part of JMS, please consult the JMS 1.1 specification for full details.< / p >
< p > A Queue is used to send messages point to point, from a producer to a consumer. The queue guarantees message ordering between these 2 points.< / p >
< h2 > Example step-by-step< / h2 >
< p > < i > To run the example, simply type < code > mvn verify< / code > from this directory< / i > < / p >
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< li > First we need to get an initial context so we can look-up the JMS connection factory and destination objects from JNDI. This initial context will get it's properties from the < code > client-jndi.properties< / code > file in the directory < code > ../common/config< / code > < / li >
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< code > InitialContext initialContext = getContext();< / code >
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< li > We look-up the JMS queue object from JNDI< / li >
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< code > Queue queue = (Queue) initialContext.lookup("/queue/exampleQueue");< / code >
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< li > We look-up the JMS connection factory object from JNDI< / li >
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< code > ConnectionFactory cf = (ConnectionFactory) initialContext.lookup("/ConnectionFactory");< / code >
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< li > We create a JMS connection< / li >
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< code > connection = cf.createConnection();< / code >
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< li > We create a JMS session. The session is created as non transacted and will auto acknowledge messages.< / li >
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< code > Session session = connection.createSession(false, Session.AUTO_ACKNOWLEDGE);< / code >
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< li > We create a JMS message producer on the session. This will be used to send the messages.< / li >
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< code > MessageProducer messageProducer = session.createProducer(topic);< / code >
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< li > We create a JMS text message that we are going to send.< / li >
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< code > TextMessage message = session.createTextMessage("This is a text message");< / code >
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< li > We send message to the queue< / li >
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< code > messageProducer.send(message);< / code >
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< li > We create a JMS Message Consumer to receive the message.< / li >
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< code > MessageConsumer messageConsumer = session.createConsumer(queue);< / code >
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< li > We start the connection. In order for delivery to occur on any consumers or subscribers on a connection, the connection must be started< / li >
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< code > connection.start();< / code >
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< li > The message arrives at the consumer. In this case we use a timeout of 5000 milliseconds but we could use a blocking 'receive()'< / li >
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< code > TextMessage messageReceived = (TextMessage) messageConsumer.receive(5000);< / code >
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< li > And finally, < b > always< / b > remember to close your JMS connections and resources after use, in a < code > finally< / code > block. Closing a JMS connection will automatically close all of its sessions, consumers, producer and browser objects< / li >
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< code > finally
{
if (initialContext != null)
{
initialContext.close();
}
if (connection != null)
{
connection.close();
}
}< / code >
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