An Introduction To Spring JMS

1. Overview

Spring provides a JMS Integration framework that simplifies the use of the JMS API. This article introduces basic concepts of such integration.

2. Maven Dependency

In order to use Spring JMS in our application, we need to add necessary artifacts in the pom.xml:

<dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-jms</artifactId>
    <version>4.3.3.RELEASE</version>
</dependency>

The newest version of the artifact can be found here.

3. The JmsTemplate

JmsTemplate class handles the creation and releasing of resources when sending or synchronously receiving messages.

Hence the class that uses this JmsTemplate only needs to implement callback interfaces as specified in the method definition.

Starting with Spring 4.1, the JmsMessagingTemplate is built on top of JmsTemplate which provides an integration with the messaging abstraction, i.e., org.springframework.messaging.Message which in turn allows us to create a message to send in a generic manner.

4. Connection Management

In order to connect and be able to send/receive messages, we need to configure a ConnectionFactory.

A ConnectionFactory is one of the JMS administered objects which are preconfigured by an administrator. A client with the help of the configuration will make the connection with a JMS provider.

Spring provides 2 types of ConnectionFactory:

• SingleConnectionFactory – is an implementation of ConnectionFactory interface, that will return the same connection on all createConnection() calls and ignore calls to close()
• CachingConnectionFactory – extends the functionality of the SingleConnectionFactory and adds enhances it with a caching of Sessions, MessageProducers, and MessageConsumers

5. Destination Management

As discussed above, along with the ConnectionFactory , destinations are also JMS administered objects and can be stored and retrieved from a JNDI.

Spring provides generic resolvers like DynamicDestinationResolver and specific resolvers such as JndiDestinationResolver.

The JmsTemplate will delegate the resolution of the destination name to one of the implementations basing on our selection.

It will also provide a property called defaultDestination – which will be used with send and receive operations that do not refer to a specific destination.

6. Message Conversion

Spring JMS would be incomplete without the support of Message Converters.

The default conversion strategy used by JmsTemplate for both ConvertAndSend() and ReceiveAndConvert() operations is the SimpleMessageConverter class.

The SimpleMessageConverter is able to handle TextMessages, BytesMessages, MapMessages, and ObjectMessages. This class implements the MessageConverter interface.

Apart from SimpleMessageConverter, Spring JMS provides some other MessageConverter classes out of the box like MappingJackson2MessageConverter, MarshallingMessageConverter, MessagingMessageConverter.

Moreover, we can create custom message conversion functionality simply by implementing the MessageConverter interface’s toMessage() and FromMessage() methods.

Let us see a sample code snippet on implementing a custom MessageConverter,

public class SampleMessageConverter implements MessageConverter {
    public Object fromMessage(Message message) 
      throws  JMSException, MessageConversionException {
        //...
    }

    public Message toMessage(Object object, Session session)
      throws  JMSException, MessageConversionException { 
        //...
    }
}

7. Sample Spring JMS

In this section, we will see how JmsTemplate is used for sending and receiving messages.

The default method for sending the message is JmsTemplate.send(). It has two key parameters of which, first parameter is the JMS destination and the second parameter is an implementation of MessageCreator which contains the callback method createMessage() that JmsTemplate will use to construct a message to be sent.

JmsTemplate.send() is good for sending plain text messages but in order to send custom messages, JmsTemplate has another method called convertAndSend().

We can see below the implementation of these methods:

public class SampleJmsMessageSender {

    private JmsTemplate jmsTemplate;
    private Queue queue;

    // setters for jmsTemplate & queue

    public void simpleSend() {
        jmsTemplate.send(queue, s -> s.createTextMessage("hello queue world"));
    }

    public void sendMessage(Employee employee) { 
        System.out.println("Jms Message Sender : " + employee); 
        Map<String, Object> map = new HashMap<>(); 
        map.put("name", employee.getName()); map.put("age", employee.getAge()); 
        jmsTemplate.convertAndSend(map); 
    }
}

Below is the message receiver class, we call it as Message-Driven POJO (MDP). We can see that the class SampleListener is implementing the MessageListener interface and provides the text specific implementation for the interface method onMessage().

Apart from onMessage() method, our SampleListener class also called a method receiveAndConvert() for receiving custom messages:

public class SampleListener implements MessageListener {

    public JmsTemplate getJmsTemplate() {
        return getJmsTemplate();
    }

    public void onMessage(Message message) {
        if (message instanceof TextMessage) {
            try {
                String msg = ((TextMessage) message).getText();
                System.out.println("Message has been consumed : " + msg);
            } catch (JMSException ex) {
                throw new RuntimeException(ex);
            }
        } else {
            throw new IllegalArgumentException("Message Error");
        }
    }

    public Employee receiveMessage() throws JMSException {
        Map map = (Map) getJmsTemplate().receiveAndConvert();
        return new Employee((String) map.get("name"), (Integer) map.get("age"));
    }
}

We saw how to implement MessageListener and below we see the configuration in Spring application context:

<bean id="messageListener" class="com.baeldung.spring.jms.SampleListener" /> 

<bean id="jmsContainer" 
  class="org.springframework.jms.listener.DefaultMessageListenerContainer"> 
    <property name="connectionFactory" ref="connectionFactory"/> 
    <property name="destinationName" ref="IN_QUEUE"/> 
    <property name="messageListener" ref="messageListener" /> 
</bean>

DefaultMessageListenerContainer is the default message listener container Spring provides along with many other specialized containers.

8. Configuration with Annotations

@JmsListener is the only annotation required to convert a method of a normal bean into a JMS listener endpoint. Spring JMS provides many more annotations to ease the JMS implementation. We can see some of the sample classes annotated classes below,

@JmsListener(destination = "myDestination")
public void SampleJmsListenerMethod(Message<Order> order) { ... }

In order to add multiple listeners to a single method we just need to add multiple @JmsListener annotation.

@EnableJms is the annotation added to one of our configuration classes to support the above discussed @JmsListener annotated methods.

@Configuration
@EnableJms
public class AppConfig {

    @Bean
    public DefaultJmsListenerContainerFactory jmsListenerContainerFactory() {
        DefaultJmsListenerContainerFactory factory 
          = new DefaultJmsListenerContainerFactory();
        factory.setConnectionFactory(connectionFactory());
        return factory;
    }
}

9. Conclusion

In this tutorial, we discussed configuration and basic concepts of Spring JMS. We also had a brief look on the Spring specific JmsTemplate classes which are used for sending and receiving messages.

You can find the code implementation in the GitHub project.