2. Introduction

This first part of the reference documentation is a high-level overview of Spring AMQP and the underlying concepts and some code snippets that will get you up and running as quickly as possible.

2.1 Quick Tour for the impatient

2.1.1 Introduction

This is the 5 minute tour to get started with Spring AMQP.

Prerequisites: install and run the RabbitMQ broker (http://www.rabbitmq.com/download.html). Then grab the spring-rabbit JAR and all its dependencies - the easiest way to do that is to declare a dependency in your build tool, e.g. for Maven:

<dependency>
  <groupId>org.springframework.amqp</groupId>
  <artifactId>spring-rabbit</artifactId>
  <version>2.0.11.BUILD-SNAPSHOT</version>
</dependency>

And for gradle:

compile 'org.springframework.amqp:spring-rabbit:2.0.11.BUILD-SNAPSHOT'

Compatibility

The minimum Spring Framework version dependency is 5.0.x.

The minimum amqp-client java client library version is 5.0.0.

Very, Very Quick

Using plain, imperative Java to send and receive a message:

ConnectionFactory connectionFactory = new CachingConnectionFactory();
AmqpAdmin admin = new RabbitAdmin(connectionFactory);
admin.declareQueue(new Queue("myqueue"));
AmqpTemplate template = new RabbitTemplate(connectionFactory);
template.convertAndSend("myqueue", "foo");
String foo = (String) template.receiveAndConvert("myqueue");

Note that there is a ConnectionFactory in the native Java Rabbit client as well. We are using the Spring abstraction in the code above. We are relying on the default exchange in the broker (since none is specified in the send), and the default binding of all queues to the default exchange by their name (hence we can use the queue name as a routing key in the send). Those behaviours are defined in the AMQP specification.

With XML Configuration

The same example as above, but externalizing the resource configuration to XML:

ApplicationContext context =
    new GenericXmlApplicationContext("classpath:/rabbit-context.xml");
AmqpTemplate template = context.getBean(AmqpTemplate.class);
template.convertAndSend("myqueue", "foo");
String foo = (String) template.receiveAndConvert("myqueue");
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:rabbit="http://www.springframework.org/schema/rabbit"
       xsi:schemaLocation="http://www.springframework.org/schema/rabbit
           http://www.springframework.org/schema/rabbit/spring-rabbit.xsd
           http://www.springframework.org/schema/beans
           http://www.springframework.org/schema/beans/spring-beans.xsd">

    <rabbit:connection-factory id="connectionFactory"/>

    <rabbit:template id="amqpTemplate" connection-factory="connectionFactory"/>

    <rabbit:admin connection-factory="connectionFactory"/>

    <rabbit:queue name="myqueue"/>

</beans>

The <rabbit:admin/> declaration by default automatically looks for beans of type Queue, Exchange and Binding and declares them to the broker on behalf of the user, hence there is no need to use that bean explicitly in the simple Java driver. There are plenty of options to configure the properties of the components in the XML schema - you can use auto-complete features of your XML editor to explore them and look at their documentation.

With Java Configuration

The same example again with the external configuration in Java:

ApplicationContext context =
    new AnnotationConfigApplicationContext(RabbitConfiguration.class);
AmqpTemplate template = context.getBean(AmqpTemplate.class);
template.convertAndSend("myqueue", "foo");
String foo = (String) template.receiveAndConvert("myqueue");

........

@Configuration
public class RabbitConfiguration {

    @Bean
    public ConnectionFactory connectionFactory() {
        return new CachingConnectionFactory("localhost");
    }

    @Bean
    public AmqpAdmin amqpAdmin() {
        return new RabbitAdmin(connectionFactory());
    }

    @Bean
    public RabbitTemplate rabbitTemplate() {
        return new RabbitTemplate(connectionFactory());
    }

    @Bean
    public Queue myQueue() {
       return new Queue("myqueue");
    }
}

2.2 What’s New

2.2.1 Changes in 2.0 Since 1.7

CachingConnectionFactory

Starting with version 2.0.2, the RabbitTemplate can be configured to use a different connection to that used by listener containers. This is to avoid deadlocked consumers when producers are blocked for any reason. See the section called “Using a Separate Connection” for more information.

AMQP Client library

Spring AMQP now uses the new 5.0.x version of the amqp-client library provided by the RabbitMQ team. This client has auto recovery configured by default; see the section called “RabbitMQ Automatic Connection/Topology recovery”.

[Note]Note

As of version 4.0, the client enables automatic recovery by default; while compatible with this feature, Spring AMQP has its own recovery mechanisms and the client recovery feature generally isn’t needed. It is recommended to disable amqp-client automatic recovery, to avoid getting AutoRecoverConnectionNotCurrentlyOpenException s when the broker is available, but the connection has not yet recovered. Starting with version 1.7.1, Spring AMQP disables it unless you explicitly create your own RabbitMQ connection factory and provide it to the CachingConnectionFactory. RabbitMQ ConnectionFactory instances created by the RabbitConnectionFactoryBean will also have the option disabled by default.

General Changes

The ExchangeBuilder now builds durable exchanges by default. The @Exchange annotation used within a @QeueueBinding also declares durable exchanges by default. The @Queue annotation used within a @RabbitListener by default declares durable queues if named and non-durable if anonymous. See the section called “Builder API for Queues and Exchanges” and the section called “Annotation-driven Listener Endpoints” for more information.

Deleted classes

UniquelyNameQueue is no longer provided. It is unusual to create a durable non auto-delete queue with a unique name. This class has been deleted; if you require its functionality, use new Queue(UUID.randomUUID().toString()).

New Listener Container

The DirectMessageListenerContainer has been added alongside the existing SimpleMessageListenerContainer. See the section called “Choosing a Container” and Section 3.1.15, “Message Listener Container Configuration” for information about choosing which container to use as well as how to configure them.

Log4j Appender

This appender is no longer available due to the end-of-life of log4j. See Section 3.2, “Logging Subsystem AMQP Appenders” for information about the available log appenders.

Logback Appender

This appender no longer captures caller data (method, line number) by default; it can be re-enabled by setting the includeCallerData configuration option. See Section 3.2, “Logging Subsystem AMQP Appenders” for information about the available log appenders.

RabbitTemplate Changes

[Important]Important

Previously, a non-transactional RabbitTemplate participated in an existing transaction if it ran on a transactional listener container thread. This was a serious bug; however, users might have relied on this behavior. Starting with version 1.6.2, you must set the channelTransacted boolean on the template for it to participate in the container transaction.

The RabbitTemplate now uses a DirectReplyToMessageListenerContainer (by default) instead of creating a new consumer for each request. See the section called “RabbitMQ Direct reply-to” for more information.

The AsyncRabbitTemplate now supports Direct reply-to; see the section called “AsyncRabbitTemplate” for more information.

The RabbitTemplate and AsyncRabbitTemplate now have receiveAndConvert and convertSendAndReceiveAsType methods that take a ParameterizedTypeReference<T> argument, allowing the caller to specify the type to convert the result to. This is particularly useful for complex types or when type information is not conveyed in message headers. Requires a SmartMessageConverter such as the Jackson2JsonMessageConverter. See Section 3.1.6, “Receiving messages”, Section 3.1.9, “Request/Reply Messaging”, the section called “AsyncRabbitTemplate”, and the section called “Converting From a Message With RabbitTemplate” for more information.

You can now use a RabbitTemplate to perform multiple operations on a dedicated channel. See the section called “Scoped Operations” for more information.

Listener Adapter

A convenient FunctionalInterface is available for using lambdas with the MessageListenerAdapter. See the section called “MessageListenerAdapter” for more information.

Listener Container Changes

Prefetch default value

The prefetch default value used to be 1, which could lead to under-utilization of efficient consumers. The default prefetch value is now 250, which should keep consumers busy in most common scenarios and thus improve throughput.

[Important]Important

There are nevertheless scenarios where the prefetch value should be low: for example, with large messages, especially if the processing is slow (messages could add up to a large amount of memory in the client process), and if strict message ordering is necessary (the prefetch value should be set back to 1 in this case). Also, with low-volume messaging and multiple consumers (including concurrency within a single listener container instance), you may wish to reduce the prefetch to get a more even distribution of messages across consumers.

For more background about prefetch, see this post about consumer utilization in RabbitMQ and this post about queuing theory.

Message Count

Previously, MessageProperties.getMessageCount() returned 0 for messages emitted by the container. This property only applies when using basicGet (e.g. from RabbitTemplate.receive() methods) and is now initialized to null for container messages.

Transaction Rollback behavior

Message requeue on transaction rollback is now consistent, regardless of whether or not a transaction manager is configured. See the section called “A note on Rollback of Received Messages” for more information.

Shutdown Behavior

If the container threads do not respond to a shutdown within shutdownTimeout, the channel(s) will be forced closed, by default. See Section 3.1.15, “Message Listener Container Configuration” for more information.

After Receive Message Post Processors

If a MessagePostProcessor in the afterReceiveMessagePostProcessors property returns null, the message is discarded (and acknowledged if appropriate).

Connection Factory Changes

The connection and channel listener interfaces now provide a mechanism to obtain information about exceptions. See the section called “Connection and Channel Listeners” and the section called “Publishing is Asynchronous - How to Detect Success and Failures” for more information.

A new ConnectionNameStrategy is now provided to populate the application-specific identification of the target RabbitMQ connection from the AbstractConnectionFactory. See Section 3.1.2, “Connection and Resource Management” for more information.

Retry Changes

The MissingMessageIdAdvice is no longer provided; it’s functionality is now built-in; see the section called “Failures in Synchronous Operations and Options for Retry” for more information.

Anonymous Queue Naming

By default, AnonymousQueues are now named with the default Base64UrlNamingStrategy instead of a simple UUID string. See the section called “AnonymousQueue” for more information.

@RabbitListener Changes

You can now provide simple queue declarations (only bound to the default exchange) in @RabbitListener annotations. See the section called “Annotation-driven Listener Endpoints” for more information.

You can now configure @RabbitListener annotations so that any exceptions thrown will be returned to the sender. You can also configure a RabbitListenerErrorHandler to handle exceptions. See the section called “Handling Exceptions” for more information.

You can now bind a queue with multiple routing keys when using the @QueueBinding annotation. Also @QueueBinding.exchange() now supports custom exchange types and declares durable exchanges by default.

You can now set the concurrency of the listener container at the annotation level rather than having to configure a different container factory for different concurrency settings.

You can now set the autoStartup property of the listener container at the annotation level, overriding the default setting in the container factory.

You can now set after receive and before send (reply) MessagePostProcessor s in the RabbitListener container factories.

See the section called “Annotation-driven Listener Endpoints” for more information.

Starting with version 2.0.3, one of the @RabbitHandler s on a class-level @RabbitListener can be designated as the default. See the section called “Multi-Method Listeners” for more information.

The listener container factory can now be configured with a RetryTemplate and, optionally, a RecoveryCallback used when sending replies. See the section called “Enable Listener Endpoint Annotations” for more information.

Container Conditional Rollback

When using an external transaction manager (e.g. JDBC), rule-based rollback is now supported when providing the container with a transaction attribute. It is also now more flexible when using a transaction advice. See the section called “Conditional Rollback” for more information.

Remove Jackson 1.x support

Deprecated in previous versions, Jackson 1.x converters and related components have now been deleted; use similar components based on Jackson 2.x. See the section called “Jackson2JsonMessageConverter” for more information.

JSON Message Converter

When the __TypeId__ is set to Hashtable for an inbound JSON message, the default conversion type is now LinkedHashMap; previously it was Hashtable. To revert to a Hashtable use setDefaultMapType on the DefaultClassMapper.

XML Parsers

When parsing Queue and Exchange XML components, the parsers no longer register the name attribute value as a bean alias if an id attribute is present. See the section called “A Note On "id" and "name" Attributes” for more information.

Blocked Connection

The com.rabbitmq.client.BlockedListener can now be injected into the org.springframework.amqp.rabbit.connection.Connection object. Also the ConnectionBlockedEvent and ConnectionUnblockedEvent events are emitted by the ConnectionFactory, when the connection is blocked or unblocked by the Broker.

See Section 3.1.2, “Connection and Resource Management” for more information.

Connection Factory Bean Changes

The RabbitConnectionFactoryBean now provides an enableHostnameVerification property; set it to true to enable host name verification. Host name verification requires overriding the amqp-client to 5.4.0 or later.

2.2.2 Earlier Releases

See Section A.2, “Previous Releases” for changes in previous versions.