RocketMQ

Since Camel 3.20

Both producer and consumer are supported

The RocketMQ component allows you to produce and consume messages from RocketMQ instances.

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

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

Since RocketMQ 5.x API is compatible with 4.x, this component works with both RocketMQ 4.x and 5.x. Users could change RocketMQ dependencies on their own.

URI format

rocketmq:topicName?[options]

The topic name determines the topic to which the produced messages will be sent to. In the case of consumers, the topic name determines the topic will be subscribed. This component uses RocketMQ push consumer by default.

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 RocketMQ component supports 15 options, which are listed below.

Name Description Default Type

namesrvAddr (common)

Name server address of RocketMQ cluster.

localhost:9876

String

sendTag (common)

Each message would be sent with this tag.

String

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

consumerGroup (consumer)

Consumer group name.

String

subscribeTags (consumer)

Subscribe tags of consumer. Multiple tags could be split by , such as TagATagB.

*

String

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

producerGroup (producer)

Producer group name.

String

replyToConsumerGroup (producer)

Consumer group name used for receiving response.

String

replyToTopic (producer)

Topic used for receiving response when using in-out pattern.

String

waitForSendResult (producer)

Whether waiting for send result before routing to next endpoint.

false

boolean

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

requestTimeoutCheckerIntervalMillis (advanced)

Check interval milliseconds of request timeout.

1000

long

requestTimeoutMillis (advanced)

Timeout milliseconds of receiving response when using in-out pattern.

10000

long

accessKey (secret)

Access key for RocketMQ ACL.

String

secretKey (secret)

Secret key for RocketMQ ACL.

String

Endpoint Options

The RocketMQ endpoint is configured using URI syntax:

rocketmq:topicName

with the following path and query parameters:

Path Parameters (1 parameters)

Name Description Default Type

topicName (common)

Required Topic name of this endpoint.

String

Query Parameters (16 parameters)

Name Description Default Type

namesrvAddr (common)

Name server address of RocketMQ cluster.

localhost:9876

String

consumerGroup (consumer)

Consumer group name.

String

subscribeTags (consumer)

Subscribe tags of consumer. Multiple tags could be split by , such as TagATagB.

*

String

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

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

producerGroup (producer)

Producer group name.

String

replyToConsumerGroup (producer)

Consumer group name used for receiving response.

String

replyToTopic (producer)

Topic used for receiving response when using in-out pattern.

String

sendTag (producer)

Each message would be sent with this tag.

String

waitForSendResult (producer)

Whether waiting for send result before routing to next endpoint.

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

requestTimeoutCheckerIntervalMillis (advanced)

Check interval milliseconds of request timeout.

1000

long

requestTimeoutMillis (advanced)

Timeout milliseconds of receiving response when using in-out pattern.

10000

long

accessKey (security)

Access key for RocketMQ ACL.

String

secretKey (security)

Secret key for RocketMQ ACL.

String

Message Headers

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

Name Description Default Type

CamelRockerMQTopic (consumer)

Constant: TOPIC

Topic of message.

String

CamelRockerMQTag (consumer)

Constant: TAG

Tag of message.

String

CamelRockerMQKey (consumer)

Constant: KEY

Key of message.

String

CamelRockerMQOverrideTopicName (producer)

Constant: OVERRIDE_TOPIC_NAME

If this header is set, the message will be routed to the topic specified by this header instead of the origin topic in endpoint.

String

CamelRockerMQOverrideTag (producer)

Constant: OVERRIDE_TAG

If this header is set, the message’s tag will be set to value specified by this header instead of the sendTag defined in endpoint.

String

CamelRockerMQOverrideMessageKey (producer)

Constant: OVERRIDE_MESSAGE_KEY

Set keys for the message. When using in-out pattern, the value will be prepended to the generated keys.

String

CamelRockerMQBrokerName (consumer)

Constant: BROKER_NAME

Broker name.

String

CamelRockerMQQueueId (consumer)

Constant: QUEUE_ID

Queue ID.

int

CamelRockerMQStoreSize (consumer)

Constant: STORE_SIZE

Store size.

int

CamelRockerMQQueueOffset (consumer)

Constant: QUEUE_OFFSET

Queue offset.

long

CamelRockerMQSysFlag (consumer)

Constant: SYS_FLAG

Sys flag.

int

CamelRockerMQBornTimestamp (consumer)

Constant: BORN_TIMESTAMP

Born timestamp.

long

CamelRockerMQBornHost (consumer)

Constant: BORN_HOST

Born host.

SocketAddress

CamelRockerMQStoreTimestamp (consumer)

Constant: STORE_TIMESTAMP

Store timestamp.

long

CamelRockerMQStoreHost (consumer)

Constant: STORE_HOST

Store host.

SocketAddress

CamelRockerMQMsgId (consumer)

Constant: MSG_ID

Msg ID.

String

CamelRockerMQCommitLogOffset (consumer)

Constant: COMMIT_LOG_OFFSET

Commit log offset.

long

CamelRockerMQBodyCrc (consumer)

Constant: BODY_CRC

Body CRC.

int

CamelRockerMQReconsumeTimes (consumer)

Constant: RECONSUME_TIMES

Reconsume times.

int

CamelRockerMQPreparedTransactionOffset (consumer)

Constant: PREPARED_TRANSACTION_OFFSET

Prepard transaction offset.

long

InOut Pattern

InOut Pattern based on Message Key. When the producer sending the message, a messageKey will be generated and append to the message’s key.

After the message sent, a consumer will listen to the topic configured by the parameter ReplyToTopic.

When a message from ReplyToTpic contains the key, it means that the reply received and continue routing.

If requestTimeoutMillis elapsed and no reply received, an exception will be thrown.

from("rocketmq:START_TOPIC?producerGroup=p1&consumerGroup=c1")

.to(ExchangePattern.InOut, "rocketmq:INTERMEDIATE_TOPIC" +
        "?producerGroup=intermediaProducer" +
        "&consumerGroup=intermediateConsumer" +
        "&replyToTopic=REPLY_TO_TOPIC" +
        "&replyToConsumerGroup=replyToConsumerGroup" +
        "&requestTimeoutMillis=30000")

.to("log:InOutRoute?showAll=true")

Examples

Receive messages from a topic named from_topic, route to to_topic.

from("rocketmq:FROM_TOPIC?namesrvAddr=localhost:9876&consumerGroup=consumer")
    .to("rocketmq:TO_TOPIC?namesrvAddr=localhost:9876&producerGroup=producer");

Setting specific headers can change routing behaviour. For example, if header RocketMQConstants.OVERRIDE_TOPIC_NAME was set, the message will be sent to ACTUAL_TARGET instead of ORIGIN_TARGET.

from("rocketmq:FROM?consumerGroup=consumer")
        .process(exchange -> {
            exchange.getMessage().setHeader(RocketMQConstants.OVERRIDE_TOPIC_NAME, "ACTUAL_TARGET");
            exchange.getMessage().setHeader(RocketMQConstants.OVERRIDE_TAG, "OVERRIDE_TAG");
            exchange.getMessage().setHeader(RocketMQConstants.OVERRIDE_MESSAGE_KEY, "OVERRIDE_MESSAGE_KEY");
        }
)
.to("rocketmq:ORIGIN_TARGET?producerGroup=producer")
.to("log:RocketRoute?showAll=true")