Red Hat Summit Red Hat Summitサポートコンソール開発者トライアルの開始お問い合わせ

このコンテンツは選択した言語では利用できません。

Chapter 27. Cron

Only consumer is supported

The Cron component is a generic interface component that allows triggering events at specific time interval specified using the Unix cron syntax (e.g. 0/2 * * * * ? to trigger an event every two seconds).

Being an interface component, the Cron component does not contain a default implementation, instead it requires that the users plug the implementation of their choice.

The following standard Camel components support the Cron endpoints:

  • Camel-quartz
  • Camel-spring

The Cron component is also supported in Camel K, which can use the Kubernetes scheduler to trigger the routes when required by the cron expression. Camel K does not require additional libraries to be plugged when using cron expressions compatible with Kubernetes cron syntax.

27.1. Dependencies
リンクのコピー

When using cron with Red Hat build of Camel Spring Boot make sure to use the following Maven dependency to have support for auto configuration: 

<dependency>
  <groupId>org.apache.camel.springboot</groupId>
  <artifactId>camel-cron-starter</artifactId>
</dependency>

Additional libraries may be needed in order to plug a specific implementation.

27.2. Configuring Options
リンクのコピー

Camel components are configured on two separate levels:

  • component level
  • endpoint level

27.2.1. Configuring Component Options
リンクのコピー

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.

27.2.2. Configuring Endpoint Options
リンクのコピー

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.

27.3. Component Options
リンクのコピー

The Cron component supports 3 options, which are listed below.

Expand
NameDescriptionDefaultType

bridgeErrorHandler (consumer)

Allows for bridging the consumer to the Camel routing Error Handler, which mean any exceptions occurred while the consumer is trying to pickup incoming messages, or the likes, will now be processed as a message and handled by the routing Error Handler. 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

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

cronService (advanced)

The id of the CamelCronService to use when multiple implementations are provided.

 

String

27.4. Endpoint Options
リンクのコピー

The Cron endpoint is configured using URI syntax: 

cron:name

with the following path and query parameters:

27.4.1. Path Parameters (1 parameters)
リンクのコピー

Expand
NameDescriptionDefaultType

name (consumer)

Required The name of the cron trigger.

 

String

27.4.2. Query Parameters (4 parameters)
リンクのコピー

Expand
NameDescriptionDefaultType

bridgeErrorHandler (consumer)

Allows for bridging the consumer to the Camel routing Error Handler, which mean any exceptions occurred while the consumer is trying to pickup incoming messages, or the likes, will now be processed as a message and handled by the routing Error Handler. 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

schedule (consumer)

Required A cron expression that will be used to generate events.

 

String

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
  • InOptionalOut
 

ExchangePattern

27.5. Usage
リンクのコピー

The component can be used to trigger events at specified times, as in the following example: 

from("cron:tab?schedule=0/1+*+*+*+*+?")
.setBody().constant("event")
.log("${body}");

The schedule expression 0/3+10+++*+? can be also written as 0/3 10 * * * ? and triggers an event every three seconds only in the tenth minute of each hour.

Parts in the schedule expression means (in order):

  • Seconds (optional)
  • Minutes
  • Hours
  • Day of month
  • Month
  • Day of week
  • Year (optional)

Schedule expressions can be made of 5 to 7 parts. When expressions are composed of 6 parts, the first items is the "seconds" part (and year is considered missing).

Other valid examples of schedule expressions are:

  • 0/2 * * * ? (5 parts, an event every two minutes)
  • 0 0/2 * * * MON-FRI 2030 (7 parts, an event every two minutes only in year 2030)

Routes can also be written using the XML DSL. 

<route>
    <from uri="cron:tab?schedule=0/1+*+*+*+*+?"/>
    <setBody>
      <constant>event</constant>
    </setBody>
    <to uri="log:info"/>
</route>

27.6. Spring Boot Auto-Configuration
リンクのコピー

The component supports 4 options, which are listed below.

Expand
NameDescriptionDefaultType

camel.component.cron.autowired-enabled

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

camel.component.cron.bridge-error-handler

Allows for bridging the consumer to the Camel routing Error Handler, which mean any exceptions occurred while the consumer is trying to pickup incoming messages, or the likes, will now be processed as a message and handled by the routing Error Handler. 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

camel.component.cron.cron-service

The id of the CamelCronService to use when multiple implementations are provided.

 

String

camel.component.cron.enabled

Whether to enable auto configuration of the cron component. This is enabled by default.

 

Boolean

Red Hat logoGithubredditYoutubeTwitter

詳細情報

試用、購入および販売

コミュニティー

Red Hat ドキュメントについて

Red Hat をお使いのお客様が、信頼できるコンテンツが含まれている製品やサービスを活用することで、イノベーションを行い、目標を達成できるようにします。 最新の更新を見る.

多様性を受け入れるオープンソースの強化

Red Hat では、コード、ドキュメント、Web プロパティーにおける配慮に欠ける用語の置き換えに取り組んでいます。このような変更は、段階的に実施される予定です。詳細情報: Red Hat ブログ.

会社概要

Red Hat は、企業がコアとなるデータセンターからネットワークエッジに至るまで、各種プラットフォームや環境全体で作業を簡素化できるように、強化されたソリューションを提供しています。

Theme

© 2026 Red Hatトップに戻る