Alibaba Message Service (MNS)

Since Camel 4.23

Both producer and consumer are supported

The Alibaba Cloud Message Service (MNS) component allows you to integrate with Alibaba Cloud MNS for queue and topic messaging.

Alibaba Cloud recommends RocketMQ for new messaging workloads. MNS remains supported, but evaluate RocketMQ or the Camel RocketMQ component for greenfield projects.

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

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

URI format

Queue endpoints:

alibaba-mns:queueName[?options]

Topic endpoints:

alibaba-mns:topic:topicName[?options]

Configuring Options

Camel components are configured on two separate levels:

  • component level

  • endpoint level

Configuring Component Options

At the component level, you set general and shared configurations that are, then, inherited by the endpoints. It is the highest configuration level.

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.

You can configure components using:

  • the Component DSL.

  • in a configuration file (application.properties, *.yaml files, etc).

  • directly in the Java code.

Configuring Endpoint Options

You usually spend more time setting up endpoints because they have many options. These options help you customize what you want the endpoint to do. The options are also categorized into whether the endpoint is used as a consumer (from), as a producer (to), or 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.

Property placeholders provide a few benefits:

  • They help prevent using hardcoded urls, port numbers, sensitive information, and other settings.

  • They allow externalizing the configuration from the code.

  • They help the code to become more flexible and reusable.

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

Component Options

The Alibaba Message Service (MNS) component supports the following options which are listed below.

Name Description Default Type

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

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

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

healthCheckConsumerEnabled (health)

Used for enabling or disabling all consumer based health checks from this component.

true

boolean

healthCheckProducerEnabled (health)

Used for enabling or disabling all producer based health checks from this component. Notice: Camel has by default disabled all producer based health-checks. You can turn on producer checks globally by setting camel.health.producersEnabled=true.

true

boolean

Endpoint Options

The Alibaba Message Service (MNS) endpoint is configured using URI syntax:

alibaba-mns:queueName

With the following path and query parameters:

Path Parameters

Name Description Default Type

queueName (common)

Required Queue name, or topic name when using the topic URI syntax.

String

Query Parameters

Name Description Default Type

accountEndpoint (common)

Required MNS account endpoint, for example https://123456.mns.cn-hangzhou.aliyuncs.com.

String

operation (common)

Operation to perform.

Enum values:

  • sendMessage

  • receiveMessage

  • deleteMessage

  • publishMessage

String

region (common)

Required Alibaba Cloud region.

String

topicName (common)

Topic name for publishMessage operations.

String

waitSeconds (common)

Long polling wait time in seconds when receiving messages.

0

int

deleteAfterRead (consumer)

Delete message from the queue after it has been processed.

true

boolean

maxMessagesPerPoll (consumer)

Maximum number of messages to receive per poll.

1

int

sendEmptyMessageWhenIdle (consumer)

If the polling consumer did not poll any files, you can enable this option to send an empty message (no body) instead.

false

boolean

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

pollStrategy (consumer (advanced))

A pluggable org.apache.camel.PollingConsumerPollingStrategy allowing you to provide your custom implementation to control error handling usually occurred during the poll operation before an Exchange have been created and being routed in Camel.

PollingConsumerPollStrategy

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

mnsClient (advanced)

Autowired Autowire an existing MNSClient instance.

MNSClient

backoffErrorThreshold (scheduler)

The number of subsequent error polls (failed due some error) that should happen before the backoffMultipler should kick-in.

int

backoffIdleThreshold (scheduler)

The number of subsequent idle polls that should happen before the backoffMultipler should kick-in.

int

backoffMultiplier (scheduler)

To let the scheduled polling consumer backoff if there has been a number of subsequent idles/errors in a row. The multiplier is then the number of polls that will be skipped before the next actual attempt is happening again. When this option is in use then backoffIdleThreshold and/or backoffErrorThreshold must also be configured.

int

delay (scheduler)

Milliseconds before the next poll.

500

long

greedy (scheduler)

If greedy is enabled, then the ScheduledPollConsumer will run immediately again, if the previous run polled 1 or more messages.

false

boolean

initialDelay (scheduler)

Milliseconds before the first poll starts.

1000

long

repeatCount (scheduler)

Specifies a maximum limit of number of fires. So if you set it to 1, the scheduler will only fire once. If you set it to 5, it will only fire five times. A value of zero or negative means fire forever.

0

long

runLoggingLevel (scheduler)

The consumer logs a start/complete log line when it polls. This option allows you to configure the logging level for that.

Enum values:

  • TRACE

  • DEBUG

  • INFO

  • WARN

  • ERROR

  • OFF

TRACE

LoggingLevel

scheduledExecutorService (scheduler)

Allows for configuring a custom/shared thread pool to use for the consumer. By default each consumer has its own single threaded thread pool.

ScheduledExecutorService

scheduler (scheduler)

To use a cron scheduler from either camel-spring or camel-quartz component. Use value spring or quartz for built in scheduler.

none

Object

schedulerProperties (scheduler)

To configure additional properties when using a custom scheduler or any of the Quartz, Spring based scheduler. This is a multi-value option with prefix: scheduler.

Map

startScheduler (scheduler)

Whether the scheduler should be auto started.

true

boolean

timeUnit (scheduler)

Time unit for initialDelay and delay options.

Enum values:

  • NANOSECONDS

  • MICROSECONDS

  • MILLISECONDS

  • SECONDS

  • MINUTES

  • HOURS

  • DAYS

MILLISECONDS

TimeUnit

useFixedDelay (scheduler)

Controls if fixed delay or fixed rate is used. See ScheduledExecutorService in JDK for details.

true

boolean

accessKey (security)

Access key for the cloud user.

String

secretKey (security)

Secret key for the cloud user.

String

serviceKeys (security)

Configuration object for cloud service authentication.

ServiceKeys

Message Headers

The Alibaba Message Service (MNS) component supports the following message header(s), which is/are listed below:

Name Description Default Type

CamelAlibabaMnsMessageId (common)

Constant: MESSAGE_ID

The MNS message id.

String

CamelAlibabaMnsReceiptHandle (common)

Constant: RECEIPT_HANDLE

The MNS receipt handle.

String

CamelAlibabaMnsMessageBodyMd5 (common)

Constant: MESSAGE_BODY_MD5

The MD5 digest of the message body.

String

CamelAlibabaMnsDelaySeconds (producer)

Constant: DELAY_SECONDS

Delay in seconds before the message becomes visible.

Integer

CamelAlibabaMnsPriority (producer)

Constant: PRIORITY

Message priority.

Integer

CamelAlibabaMnsMessageTag (producer)

Constant: MESSAGE_TAG

Message tag for topic publish operations.

String

CamelAlibabaMnsDequeueCount (consumer)

Constant: DEQUEUE_COUNT

Number of times the message has been dequeued.

Integer

CamelAlibabaMnsEnqueueTime (consumer)

Constant: ENQUEUE_TIME

Time when the message was enqueued.

Date

CamelAlibabaMnsNextVisibleTime (consumer)

Constant: NEXT_VISIBLE_TIME

Next time the message becomes visible.

Date

CamelAlibabaMnsFirstDequeueTime (consumer)

Constant: FIRST_DEQUEUE_TIME

Time when the message was first dequeued.

Date

Usage

Operations

The component supports the following operations:

  • sendMessage - send a message to a queue (producer)

  • receiveMessage - receive messages from a queue (consumer)

  • deleteMessage - delete a message from a queue using its receipt handle (producer)

  • publishMessage - publish a message to a topic (producer)

Queue producer example

from("direct:start")
    .setBody(constant("Hello MNS"))
    .to("alibaba-mns:myQueue?operation=sendMessage&region=cn-hangzhou&accountEndpoint=https://123456.mns.cn-hangzhou.aliyuncs.com&accessKey=RAW(accessKey)&secretKey=RAW(secretKey)");

Topic producer example

from("direct:start")
    .setBody(constant("Hello Topic"))
    .to("alibaba-mns:topic:myTopic?operation=publishMessage&region=cn-hangzhou&accountEndpoint=https://123456.mns.cn-hangzhou.aliyuncs.com&accessKey=RAW(accessKey)&secretKey=RAW(secretKey)");

Queue consumer example

from("alibaba-mns:myQueue?region=cn-hangzhou&accountEndpoint=https://123456.mns.cn-hangzhou.aliyuncs.com&accessKey=RAW(accessKey)&secretKey=RAW(secretKey)&deleteAfterRead=true")
    .to("bean:processMessage");

Exchange properties evaluated by the producer

Property Type Description

CamelAlibabaMnsOperation

String

Operation to perform

CamelAlibabaMnsQueueName

String

Queue name override

CamelAlibabaMnsTopicName

String

Topic name for publish operations

CamelAlibabaMnsReceiptHandle

String

Receipt handle for delete operations

Exchange properties set by the producer

Property Type Description

CamelAlibabaMnsMessageId

String

Message id returned by MNS

CamelAlibabaMnsRequestId

String

Request id returned by MNS

CamelAlibabaMnsMessageBodyMd5

String

MD5 digest of the message body

Examples

For more examples, see the unit tests in the camel-alibaba-mns module.

Back to top