Spring RabbitMQ

Since Camel 3.8

Both producer and consumer are supported

The Spring RabbitMQ component allows you to produce and consume messages from RabbitMQ instances. Using the Spring RabbitMQ client.

Maven users will need to add the following dependency to their pom.xml for this component:

<dependency>
    <groupId>org.apache.camel</groupId>
    <artifactId>camel-spring-rabbitmq</artifactId>
    <version>x.x.x</version>
    <!-- use the same version as your Camel core version -->
</dependency>

URI format

spring-rabbitmq:exchangeName?[options]

The exchange name determines the exchange to which the produced messages will be sent to. In the case of consumers, the exchange name determines the exchange the queue will be bound to.

Configuring Options

Camel components are configured on two separate levels:

  • component level

  • endpoint level

Configuring Component Options

The component level is the highest level which holds general and common configurations that are inherited by the endpoints. For example a component may have security settings, credentials for authentication, urls for network connection and so forth.

Some components only have a few options, and others may have many. Because components typically have pre configured defaults that are commonly used, then you may often only need to configure a few options on a component; or none at all.

Configuring components can be done with the Component DSL, in a configuration file (application.properties|yaml), or directly with Java code.

Configuring Endpoint Options

Where you find yourself configuring the most is on endpoints, as endpoints often have many options, which allows you to configure what you need the endpoint to do. The options are also categorized into whether the endpoint is used as consumer (from) or as a producer (to), or used for both.

Configuring endpoints is most often done directly in the endpoint URI as path and query parameters. You can also use the Endpoint DSL and DataFormat DSL as a type safe way of configuring endpoints and data formats in Java.

A good practice when configuring options is to use Property Placeholders, which allows to not hardcode urls, port numbers, sensitive information, and other settings. In other words placeholders allows to externalize the configuration from your code, and gives more flexibility and reuse.

The following two sections lists all the options, firstly for the component followed by the endpoint.

Component Options

The Spring RabbitMQ component supports 29 options, which are listed below.

Name Description Default Type

amqpAdmin (common)

Autowired Optional AMQP Admin service to use for auto declaring elements (queues, exchanges, bindings).

AmqpAdmin

connectionFactory (common)

Autowired The connection factory to be use. A connection factory must be configured either on the component or endpoint.

ConnectionFactory

testConnectionOnStartup (common)

Specifies whether to test the connection on startup. This ensures that when Camel starts that all the JMS consumers have a valid connection to the JMS broker. If a connection cannot be granted then Camel throws an exception on startup. This ensures that Camel is not started with failed connections. The JMS producers is tested as well.

false

boolean

autoDeclare (consumer)

Specifies whether the consumer should auto declare binding between exchange, queue and routing key when starting. Enabling this can be good for development to make it easy to standup exchanges, queues and bindings on the broker.

false

boolean

autoStartup (consumer)

Specifies whether the consumer container should auto-startup.

true

boolean

bridgeErrorHandler (consumer)

Allows for bridging the consumer to the Camel routing Error Handler, which mean any exceptions (if possible) occurred while the Camel consumer is trying to pickup incoming messages, or the likes, will now be processed as a message and handled by the routing Error Handler. Important: This is only possible if the 3rd party component allows Camel to be alerted if an exception was thrown. Some components handle this internally only, and therefore bridgeErrorHandler is not possible. In other situations we may improve the Camel component to hook into the 3rd party component and make this possible for future releases. By default the consumer will use the org.apache.camel.spi.ExceptionHandler to deal with exceptions, that will be logged at WARN or ERROR level and ignored.

false

boolean

deadLetterExchange (consumer)

The name of the dead letter exchange.

String

deadLetterExchangeType (consumer)

The type of the dead letter exchange.

Enum values:

  • direct

  • fanout

  • headers

  • topic

direct

String

deadLetterQueue (consumer)

The name of the dead letter queue.

String

deadLetterRoutingKey (consumer)

The routing key for the dead letter exchange.

String

maximumRetryAttempts (consumer)

How many times a Rabbitmq consumer will retry the same message if Camel failed to process the message.

5

int

rejectAndDontRequeue (consumer)

Whether a Rabbitmq consumer should reject the message without requeuing. This enables failed messages to be sent to a Dead Letter Exchange/Queue, if the broker is so configured.

true

boolean

retryDelay (consumer)

Delay in msec a Rabbitmq consumer will wait before redelivering a message that Camel failed to process.

1000

int

concurrentConsumers (consumer (advanced))

The number of consumers.

1

int

errorHandler (consumer (advanced))

To use a custom ErrorHandler for handling exceptions from the message listener (consumer).

ErrorHandler

listenerContainerFactory (consumer (advanced))

To use a custom factory for creating and configuring ListenerContainer to be used by the consumer for receiving messages.

ListenerContainerFactory

maxConcurrentConsumers (consumer (advanced))

The maximum number of consumers (available only with SMLC).

Integer

messageListenerContainerType (consumer (advanced))

The type of the MessageListenerContainer.

Enum values:

  • DMLC

  • SMLC

DMLC

String

prefetchCount (consumer (advanced))

Tell the broker how many messages to send to each consumer in a single request. Often this can be set quite high to improve throughput.

250

int

retry (consumer (advanced))

Custom retry configuration to use. If this is configured then the other settings such as maximumRetryAttempts for retry are not in use.

RetryOperationsInterceptor

shutdownTimeout (consumer (advanced))

The time to wait for workers in milliseconds after the container is stopped. If any workers are active when the shutdown signal comes they will be allowed to finish processing as long as they can finish within this timeout.

5000

long

allowNullBody (producer)

Whether to allow sending messages with no body. If this option is false and the message body is null, then an MessageConversionException is thrown.

false

boolean

lazyStartProducer (producer)

Whether the producer should be started lazy (on the first message). By starting lazy you can use this to allow CamelContext and routes to startup in situations where a producer may otherwise fail during starting and cause the route to fail being started. By deferring this startup to be lazy then the startup failure can be handled during routing messages via Camel’s routing error handlers. Beware that when the first message is processed then creating and starting the producer may take a little time and prolong the total processing time of the processing.

false

boolean

replyTimeout (producer)

Specify the timeout in milliseconds to be used when waiting for a reply message when doing request/reply messaging. The default value is 5 seconds. A negative value indicates an indefinite timeout.

5000

long

autowiredEnabled (advanced)

Whether autowiring is enabled. This is used for automatic autowiring options (the option must be marked as autowired) by looking up in the registry to find if there is a single instance of matching type, which then gets configured on the component. This can be used for automatic configuring JDBC data sources, JMS connection factories, AWS Clients, etc.

true

boolean

ignoreDeclarationExceptions (advanced)

Switch on ignore exceptions such as mismatched properties when declaring.

false

boolean

messageConverter (advanced)

To use a custom MessageConverter so you can be in control how to map to/from a org.springframework.amqp.core.Message.

MessageConverter

messagePropertiesConverter (advanced)

To use a custom MessagePropertiesConverter so you can be in control how to map to/from a org.springframework.amqp.core.MessageProperties.

MessagePropertiesConverter

headerFilterStrategy (filter)

To use a custom org.apache.camel.spi.HeaderFilterStrategy to filter header to and from Camel message.

HeaderFilterStrategy

Endpoint Options

The Spring RabbitMQ endpoint is configured using URI syntax:

spring-rabbitmq:exchangeName

with the following path and query parameters:

Path Parameters (1 parameters)

Name Description Default Type

exchangeName (common)

Required The exchange name determines the exchange to which the produced messages will be sent to. In the case of consumers, the exchange name determines the exchange the queue will be bound to. Note: to use default exchange then do not use empty name, but use default instead.

String

Query Parameters (37 parameters)

Name Description Default Type

connectionFactory (common)

The connection factory to be use. A connection factory must be configured either on the component or endpoint.

ConnectionFactory

disableReplyTo (common)

Specifies whether Camel ignores the ReplyTo header in messages. If true, Camel does not send a reply back to the destination specified in the ReplyTo header. You can use this option if you want Camel to consume from a route and you do not want Camel to automatically send back a reply message because another component in your code handles the reply message. You can also use this option if you want to use Camel as a proxy between different message brokers and you want to route message from one system to another.

false

boolean

routingKey (common)

The value of a routing key to use. Default is empty which is not helpful when using the default (or any direct) exchange, but fine if the exchange is a headers exchange for instance.

String

testConnectionOnStartup (common)

Specifies whether to test the connection on startup. This ensures that when Camel starts that all the JMS consumers have a valid connection to the JMS broker. If a connection cannot be granted then Camel throws an exception on startup. This ensures that Camel is not started with failed connections. The JMS producers is tested as well.

false

boolean

acknowledgeMode (consumer)

Flag controlling the behaviour of the container with respect to message acknowledgement. The most common usage is to let the container handle the acknowledgements (so the listener doesn’t need to know about the channel or the message). Set to AcknowledgeMode.MANUAL if the listener will send the acknowledgements itself using Channel.basicAck(long, boolean). Manual acks are consistent with either a transactional or non-transactional channel, but if you are doing no other work on the channel at the same other than receiving a single message then the transaction is probably unnecessary. Set to AcknowledgeMode.NONE to tell the broker not to expect any acknowledgements, and it will assume all messages are acknowledged as soon as they are sent (this is autoack in native Rabbit broker terms). If AcknowledgeMode.NONE then the channel cannot be transactional (so the container will fail on start up if that flag is accidentally set).

Enum values:

  • NONE

  • MANUAL

  • AUTO

AcknowledgeMode

asyncConsumer (consumer)

Whether the consumer processes the Exchange asynchronously. If enabled then the consumer may pickup the next message from the queue, while the previous message is being processed asynchronously (by the Asynchronous Routing Engine). This means that messages may be processed not 100% strictly in order. If disabled (as default) then the Exchange is fully processed before the consumer will pickup the next message from the queue.

false

boolean

autoDeclare (consumer)

Specifies whether the consumer should auto declare binding between exchange, queue and routing key when starting.

true

boolean

autoStartup (consumer)

Specifies whether the consumer container should auto-startup.

true

boolean

deadLetterExchange (consumer)

The name of the dead letter exchange.

String

deadLetterExchangeType (consumer)

The type of the dead letter exchange.

Enum values:

  • direct

  • fanout

  • headers

  • topic

direct

String

deadLetterQueue (consumer)

The name of the dead letter queue.

String

deadLetterRoutingKey (consumer)

The routing key for the dead letter exchange.

String

exchangeType (consumer)

The type of the exchange.

Enum values:

  • direct

  • fanout

  • headers

  • topic

direct

String

exclusive (consumer)

Set to true for an exclusive consumer.

false

boolean

maximumRetryAttempts (consumer)

How many times a Rabbitmq consumer will retry the same message if Camel failed to process the message.

5

int

noLocal (consumer)

Set to true for an no-local consumer.

false

boolean

queues (consumer)

The queue(s) to use for consuming messages. Multiple queue names can be separated by comma. If none has been configured then Camel will generate an unique id as the queue name for the consumer.

String

rejectAndDontRequeue (consumer)

Whether a Rabbitmq consumer should reject the message without requeuing. This enables failed messages to be sent to a Dead Letter Exchange/Queue, if the broker is so configured.

true

boolean

retryDelay (consumer)

Delay in millis a Rabbitmq consumer will wait before redelivering a message that Camel failed to process.

1000

int

bridgeErrorHandler (consumer (advanced))

Allows for bridging the consumer to the Camel routing Error Handler, which mean any exceptions (if possible) occurred while the Camel consumer is trying to pickup incoming messages, or the likes, will now be processed as a message and handled by the routing Error Handler. Important: This is only possible if the 3rd party component allows Camel to be alerted if an exception was thrown. Some components handle this internally only, and therefore bridgeErrorHandler is not possible. In other situations we may improve the Camel component to hook into the 3rd party component and make this possible for future releases. By default the consumer will use the org.apache.camel.spi.ExceptionHandler to deal with exceptions, that will be logged at WARN or ERROR level and ignored.

false

boolean

concurrentConsumers (consumer (advanced))

The number of consumers.

Integer

exceptionHandler (consumer (advanced))

To let the consumer use a custom ExceptionHandler. Notice if the option bridgeErrorHandler is enabled then this option is not in use. By default the consumer will deal with exceptions, that will be logged at WARN or ERROR level and ignored.

ExceptionHandler

exchangePattern (consumer (advanced))

Sets the exchange pattern when the consumer creates an exchange.

Enum values:

  • InOnly

  • InOut

ExchangePattern

maxConcurrentConsumers (consumer (advanced))

The maximum number of consumers (available only with SMLC).

Integer

messageListenerContainerType (consumer (advanced))

The type of the MessageListenerContainer.

Enum values:

  • DMLC

  • SMLC

DMLC

String

prefetchCount (consumer (advanced))

Tell the broker how many messages to send in a single request. Often this can be set quite high to improve throughput.

Integer

retry (consumer (advanced))

Custom retry configuration to use. If this is configured then the other settings such as maximumRetryAttempts for retry are not in use.

RetryOperationsInterceptor

allowNullBody (producer)

Whether to allow sending messages with no body. If this option is false and the message body is null, then an MessageConversionException is thrown.

false

boolean

confirm (producer)

Controls whether to wait for confirms. The connection factory must be configured for publisher confirms and this method. auto = Camel detects if the connection factory uses confirms or not. disabled = Confirms is disabled. enabled = Confirms is enabled.

Enum values:

  • auto

  • enabled

  • disabled

auto

String

confirmTimeout (producer)

Specify the timeout in milliseconds to be used when waiting for a message sent to be confirmed by RabbitMQ when doing send only messaging (InOnly). The default value is 5 seconds. A negative value indicates an indefinite timeout.

5000

long

replyTimeout (producer)

Specify the timeout in milliseconds to be used when waiting for a reply message when doing request/reply (InOut) messaging. The default value is 30 seconds. A negative value indicates an indefinite timeout (Beware that this will cause a memory leak if a reply is not received).

30000

long

usePublisherConnection (producer)

Use a separate connection for publishers and consumers.

false

boolean

lazyStartProducer (producer (advanced))

Whether the producer should be started lazy (on the first message). By starting lazy you can use this to allow CamelContext and routes to startup in situations where a producer may otherwise fail during starting and cause the route to fail being started. By deferring this startup to be lazy then the startup failure can be handled during routing messages via Camel’s routing error handlers. Beware that when the first message is processed then creating and starting the producer may take a little time and prolong the total processing time of the processing.

false

boolean

args (advanced)

Specify arguments for configuring the different RabbitMQ concepts, a different prefix is required for each element: arg.consumer. arg.exchange. arg.queue. arg.binding. arg.dlq.exchange. arg.dlq.queue. arg.dlq.binding. For example to declare a queue with message ttl argument: args=arg.queue.x-message-ttl=60000.

Map

messageConverter (advanced)

To use a custom MessageConverter so you can be in control how to map to/from a org.springframework.amqp.core.Message.

MessageConverter

messagePropertiesConverter (advanced)

To use a custom MessagePropertiesConverter so you can be in control how to map to/from a org.springframework.amqp.core.MessageProperties.

MessagePropertiesConverter

synchronous (advanced)

Sets whether synchronous processing should be strictly used.

false

boolean

Message Headers

The Spring RabbitMQ component supports 20 message header(s), which is/are listed below:

Name Description Default Type

CamelSpringRabbitmqRoutingOverrideKey (producer)

Constant: ROUTING_OVERRIDE_KEY

To override the endpoint configuration’s routing key.

String

CamelSpringRabbitmqExchangeOverrideName (producer)

Constant: EXCHANGE_OVERRIDE_NAME

To override the endpoint configuration’s exchange name.

String

CamelSpringRabbitmqRedelivered (consumer)

Constant: REDELIVERED

Whether the message was previously delivered and requeued.

Boolean

CamelSpringRabbitmqDeliveryTag (consumer)

Constant: DELIVERY_TAG

Delivery tag for manual acknowledge mode.

long

CamelSpringRabbitmqExchangeName (consumer)

Constant: EXCHANGE_NAME

The exchange name that was used when publishing the message.

String

CamelSpringRabbitmqRoutingKey (consumer)

Constant: ROUTING_KEY

The routing key that was used when publishing the message.

String

CamelSpringRabbitmqDeliveryMode (common)

Constant: DELIVERY_MODE

The message delivery mode.

MessageDeliveryMode

CamelSpringRabbitmqType (common)

Constant: TYPE

Application-specific message type.

String

CamelSpringRabbitmqContentType (common)

Constant: CONTENT_TYPE

The message content type.

String

CamelSpringRabbitmqContentLength (common)

Constant: CONTENT_LENGTH

The message content length.

long

CamelSpringRabbitmqContentEncoding (common)

Constant: CONTENT_ENCODING

Content encoding used by applications.

String

CamelSpringRabbitmqMessageId (common)

Constant: MESSAGE_ID

Arbitrary message id.

String

CamelSpringRabbitmqCorrelationId (common)

Constant: CORRELATION_ID

Identifier to correlate RPC responses with requests.

String

CamelSpringRabbitmqReplyTo (common)

Constant: REPLY_TO

Commonly used to name a callback queue.

String

CamelSpringRabbitmqExpiration (common)

Constant: EXPIRATION

Per-message TTL.

String

CamelSpringRabbitmqTimestamp (common)

Constant: TIMESTAMP

Application-provided timestamp.

Date

CamelSpringRabbitmqUserId (common)

Constant: USER_ID

Validated user id.

String

CamelSpringRabbitmqAppId (common)

Constant: APP_ID

The application name.

String

CamelSpringRabbitmqPriority (common)

Constant: PRIORITY

The message priority.

Integer

CamelSpringRabbitmqClusterId (common)

Constant: CLUSTER_ID

The cluster id.

String

Using a connection factory

To connect to RabbitMQ you need to setup a ConnectionFactory (same as with JMS) with the login details such as:

It is recommended to use CachingConnectionFactory from spring-rabbit as it comes with connection pooling out of the box. 
<bean id="rabbitConnectionFactory" class="org.springframework.amqp.rabbit.connection.CachingConnectionFactory">
  <property name="uri" value="amqp://lolcalhost:5672"/>
</bean>

The ConnectionFactory is auto-detected by default, so you can just do

<camelContext>
  <route>
    <from uri="direct:cheese"/>
    <to uri="spring-rabbitmq:foo?routingKey=cheese"/>
  </route>
</camelContext>

Default Exchange Name

To use default exchange name (which would be an empty exchange name in RabbitMQ) then you should use default as name in the endpoint uri, such as:

to("spring-rabbitmq:default?routingKey=foo")

Auto declare exchanges, queues and bindings

Before you can send or receive messages from RabbitMQ, then exchanges, queues and bindings must be setup first.

In development mode it may be desirable to let Camel automatic do this. You can enable this by setting autoDeclare=true on the SpringRabbitMQComponent.

Then Spring RabbitMQ will automatic necessary declare the elements and setup the binding between the exchange, queue and routing keys.

The elements can be configured using the multi-valued args option.

For example to specify the queue as durable and exclusive, you can configure the endpoint uri with arg.queue.durable=true&arg.queue.exclusive=true.

Exchanges

Option Type Description Default

autoDelete

boolean

True if the server should delete the exchange when it is no longer in use (if all bindings are deleted).

false

durable

boolean

A durable exchange will survive a server restart.

true

You can also configure any additional x- arguments. See details in the RabbitMQ documentation.

Queues

Option Type Description Default

autoDelete

boolean

True if the server should delete the exchange when it is no longer in use (if all bindings are deleted).

false

durable

boolean

A durable queue will survive a server restart.

false

exclusive

boolean

Whether the queue is exclusive

false

x-dead-letter-exchange

String

The name of the dead letter exchange. If none configured then the component configured value is used.

x-dead-letter-routing-key

String

The routing key for the dead letter exchange. If none configured then the component configured value is used.

You can also configure any additional x- arguments, such as the message time to live, via x-message-ttl, and many others. See details in the RabbitMQ documentation.

Mapping from Camel to RabbitMQ

The message body is mapped from Camel Message body to a byte[] which is the type that RabbitMQ uses for message body. Camel wil use its type converter to convert the message body to byte array.

Spring Rabbit comes out of the box with support for mapping Java serialized objects but Camel Spring RabbitMQ does not support this due to security vulnerabilities and using Java objects is a bad design as it enforces strong coupling.

Custom message headers is mapped from Camel Message headers to RabbitMQ headers. This behaviour can be customized by configuring a new implementation of HeaderFilterStrategy on the Camel component.

Request / Reply

Request and reply messaging is supported using RabbitMQ direct reply-to.

The example below will do request/reply, where the message is sent via the cheese exchange name and routing key foo.bar, which is being consumed by the 2nd Camel route, that prepends the message with `Hello `, and then sends back the message.

So if we send World as message body to direct:start then, we will se the message being logged

  • log:request ⇒ World

  • log:input ⇒ World

  • log:response ⇒ Hello World

from("direct:start")
    .to("log:request")
    .to(ExchangePattern.InOut, "spring-rabbitmq:cheese?routingKey=foo.bar")
    .to("log:response");

from("spring-rabbitmq:cheese?queues=myqueue&routingKey=foo.bar")
    .to("log:input")
    .transform(body().prepend("Hello "));

Reuse endpoint and send to different destinations computed at runtime

If you need to send messages to a lot of different RabbitMQ exchanges, it makes sense to reuse a endpoint and specify the real destination in a message header. This allows Camel to reuse the same endpoint, but send to different exchanges. This greatly reduces the number of endpoints created and economizes on memory and thread resources.

Using toD is easier than specifying the dynamic destination with headers

You can specify using the following headers:

Header Type Description

CamelSpringRabbitmqExchangeOverrideName

String

The exchange name.

CamelSpringRabbitmqRoutingOverrideKey

String

The routing key.

For example, the following route shows how you can compute a destination at run time and use it to override the exchange appearing in the endpoint URL:

from("file://inbox")
  .to("bean:computeDestination")
  .to("spring-rabbitmq:dummy");

The exchange name, dummy, is just a placeholder. It must be provided as part of the RabbitMQ endpoint URL, but it will be ignored in this example.

In the computeDestination bean, specify the real destination by setting the CamelRabbitmqExchangeOverrideName header as follows:

public void setExchangeHeader(Exchange exchange) {
   String region = ....
   exchange.getIn().setHeader("CamelSpringRabbitmqExchangeOverrideName", "order-" + region);
}

Then Camel will read this header and use it as the exchange name instead of the one configured on the endpoint. So, in this example Camel sends the message to spring-rabbitmq:order-emea, assuming the region value was emea.

Keep in mind that the producer removes both CamelSpringRabbitmqExchangeOverrideName and CamelSpringRabbitmqRoutingOverrideKey headers from the exchange and do not propagate them to the created Rabbitmq message in order to avoid the accidental loops in the routes (in scenarios when the message will be forwarded to the another RabbitMQ endpoint).

Using toD

If you need to send messages to a lot of different exchanges, it makes sense to reuse a endpoint and specify the dynamic destinations with simple language using toD.

For example suppose you need to send messages to exchanges with order types, then using toD could for example be done as follows:

from("direct:order")
  .toD("spring-rabbit:order-${header.orderType}");

Manual Acknowledgement

If we need to manually acknowledge a message for some use case we can do it by setting and acknowledgeMode to Manual and using the below snippet of code to get Channel and deliveryTag to manually acknowledge the message:

from("spring-rabbitmq:%s?queues=%s&acknowledgeMode=MANUAL")
    .process(exchange -> {
        Channel channel = exchange.getProperty(SpringRabbitMQConstants.CHANNEL, Channel.class);
        long deliveryTag = exchange.getMessage().getHeader(SpringRabbitMQConstants.DELIVERY_TAG, long.class);
        channel.basicAck(deliveryTag, false);
    })