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Chapter 137. SpringBatch
Spring Batch Component
The spring-batch: component and support classes provide integration bridge between Camel and Spring Batch infrastructure.
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-batch</artifactId>
<version>x.x.x</version>
<!-- use the same version as your Camel core version -->
</dependency>URI format
spring-batch:jobName[?options]
Where jobName represents the name of the Spring Batch job located in the Camel registry.
Warning
This component can only be used to define producer endpoints, which means that you cannot use the Spring Batch component in a
from() statement.
Options
| Name | Default Value | Description |
|---|---|---|
jobLauncherRef
|
null
|
Deprecated and will be removed in Camel 3.0!Camel 2.10: Use jobLauncher=#theName instead. |
jobLauncher
|
null
|
Camel 2.11.1: Explicitly specifies a JobLauncher to be used from the Camel Registry.
|
Usage
When Spring Batch component receives the message, it triggers the job execution. The job will be executed using the
org.springframework.batch.core.launch.JobLaucher instance resolved according to the following algorithm:
- if
JobLauncheris manually set on the component, then use it. - if
jobLauncherRefoption is set on the component, then search Camel Registry for theJobLauncherwith the given name. Deprecated and will be removed in Camel 3.0! - if there is
JobLauncherregistered in the Camel Registry under jobLauncher name, then use it. - if none of the steps above allow to resolve the
JobLauncherand there is exactly oneJobLauncherinstance in the Camel Registry, then use it.
All headers found in the message are passed to the
JobLauncher as job parameters. String, Long, Double and java.util.Date values are copied to the org.springframework.batch.core.JobParametersBuilder - other data types are converted to Strings.
Examples
Triggering the Spring Batch job execution:
from("direct:startBatch").to("spring-batch:myJob");
Triggering the Spring Batch job execution with the
JobLauncher set explicitly.
from("direct:startBatch").to("spring-batch:myJob?jobLauncherRef=myJobLauncher");
Starting from the Camel 2.11.1
JobExecution instance returned by the JobLauncher is forwarded by the SpringBatchProducer as the output message. You can use the JobExecution instance to perform some operations using the Spring Batch API directly.
from("direct:startBatch").to("spring-batch:myJob").to("mock:JobExecutions");
...
MockEndpoint mockEndpoint = ...;
JobExecution jobExecution = mockEndpoint.getExchanges().get(0).getIn().getBody(JobExecution.class);
BatchStatus currentJobStatus = jobExecution.getStatus();
Support classes
Apart from the Component, Camel Spring Batch provides also support classes, which can be used to hook into Spring Batch infrastructure.
CamelItemReader
CamelItemReader can be used to read batch data directly from the Camel infrastructure.
For example the snippet below configures Spring Batch to read data from JMS queue.
<bean id="camelReader" class="org.apache.camel.component.spring.batch.support.CamelItemReader">
<constructor-arg ref="consumerTemplate"/>
<constructor-arg value="jms:dataQueue"/>
</bean>
<batch:job id="myJob">
<batch:step id="step">
<batch:tasklet>
<batch:chunk reader="camelReader" writer="someWriter" commit-interval="100"/>
</batch:tasklet>
</batch:step>
</batch:job>CamelItemWriter
CamelItemWriter has similar purpose as CamelItemReader, but it is dedicated to write chunk of the processed data.
For example the snippet below configures Spring Batch to write data to a JMS queue.
<bean id="camelwriter" class="org.apache.camel.component.spring.batch.support.CamelItemWriter">
<constructor-arg ref="producerTemplate"/>
<constructor-arg value="jms:dataQueue"/>
</bean>
<batch:job id="myJob">
<batch:step id="step">
<batch:tasklet>
<batch:chunk reader="someReader" writer="camelwriter" commit-interval="100"/>
</batch:tasklet>
</batch:step>
</batch:job>CamelItemProcessor
CamelItemProcessor is the implementation of Spring Batch org.springframework.batch.item.ItemProcessor interface. The latter implementation relays on Request Reply pattern to delegate the processing of the batch item to the Camel infrastructure. The item to process is sent to the Camel endpoint as the body of the message.
For example the snippet below performs simple processing of the batch item using the Direct endpoint and the Simple expression language.
<camel:camelContext>
<camel:route>
<camel:from uri="direct:processor"/>
<camel:setExchangePattern pattern="InOut"/>
<camel:setBody>
<camel:simple>Processed ${body}</camel:simple>
</camel:setBody>
</camel:route>
</camel:camelContext>
<bean id="camelProcessor" class="org.apache.camel.component.spring.batch.support.CamelItemProcessor">
<constructor-arg ref="producerTemplate"/>
<constructor-arg value="direct:processor"/>
</bean>
<batch:job id="myJob">
<batch:step id="step">
<batch:tasklet>
<batch:chunk reader="someReader" writer="someWriter" processor="camelProcessor" commit-interval="100"/>
</batch:tasklet>
</batch:step>
</batch:job>CamelJobExecutionListener
CamelJobExecutionListener is the implementation of the org.springframework.batch.core.JobExecutionListener interface sending job execution events to the Camel endpoint.
The
org.springframework.batch.core.JobExecution instance produced by the Spring Batch is sent as a body of the message. To distinguish between before- and after-callbacks SPRING_BATCH_JOB_EVENT_TYPE header is set to the BEFORE or AFTER value.
The example snippet below sends Spring Batch job execution events to the JMS queue.
<bean id="camelJobExecutionListener" class="org.apache.camel.component.spring.batch.support.CamelJobExecutionListener">
<constructor-arg ref="producerTemplate"/>
<constructor-arg value="jms:batchEventsBus"/>
</bean>
<batch:job id="myJob">
<batch:step id="step">
<batch:tasklet>
<batch:chunk reader="someReader" writer="someWriter" commit-interval="100"/>
</batch:tasklet>
</batch:step>
<batch:listeners>
<batch:listener ref="camelJobExecutionListener"/>
</batch:listeners>
</batch:job>