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Chapter 134. Spring Batch
Since Camel 2.10
Only producer is supported
The Spring Batch component and support classes provide integration bridge between Camel and Spring Batch infrastructure.
134.1. Dependencies
When using spring-batch with Red Hat build of Camel Spring Boot, use the following Maven dependency to enable support for auto-configuration:
<dependency> <groupId>org.apache.camel.springboot</groupId> <artifactId>camel-spring-batch-starter</artifactId> </dependency>
<dependency>
<groupId>org.apache.camel.springboot</groupId>
<artifactId>camel-spring-batch-starter</artifactId>
</dependency>134.2. URI format
spring-batch:jobName[?options]
spring-batch:jobName[?options]
Where, jobName represents the name of the Spring Batch job located in the Camel registry. If a JobRegistry is provided is used to locate the job.
This component is only used to define producer endpoints, that means you cannot use the Spring Batch component in a from() statement.
134.3. Configuring Options
Camel components are configured on two separate levels:
- component level
- endpoint level
134.3.1. 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.
134.3.2. 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.
134.4. Component Options
The Spring Batch component supports 4 options, which are listed below.
| Name | Description | Default | Type |
|---|---|---|---|
| jobLauncher (producer) | Explicitly specifies a JobLauncher to be used. | JobLauncher | |
| jobRegistry (producer) | Explicitly specifies a JobRegistry to be used. | JobRegistry | |
| 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 |
134.5. Endpoint Options
The Spring Batch endpoint is configured using URI syntax:
spring-batch:jobName
spring-batch:jobNameFollowing are the path and query parameters:
134.5.1. Path Parameters (1 parameters)
| Name | Description | Default | Type |
|---|---|---|---|
| jobName (producer) | Required The name of the Spring Batch job located in the registry. | String |
134.5.2. Query Parameters (4 parameters)
| Name | Description | Default | Type |
|---|---|---|---|
| jobFromHeader (producer) | Explicitly defines if the jobName should be taken from the headers instead of the URI. | false | boolean |
| jobLauncher (producer) | Explicitly specifies a JobLauncher to be used. | JobLauncher | |
| jobRegistry (producer) | Explicitly specifies a JobRegistry to be used. | JobRegistry | |
| 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 |
134.6. Usage
When Spring Batch component receives the message, it triggers the job execution. The job is 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. -
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 and other data types are converted to Strings.
134.7. Examples
Triggering the Spring Batch job execution:
from("direct:startBatch").to("spring-batch:myJob");
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");
from("direct:startBatch").to("spring-batch:myJob?jobLauncherRef=myJobLauncher");
A 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();
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();134.8. Support classes
Apart from the component, Camel Spring Batch also provides support classes that you can use to hook into Spring Batch infrastructure.
134.8.1. 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>
<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>134.8.2. 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 read data from 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>
<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>134.8.3. 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>
<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>134.8.4. 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>
<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>134.9. Spring Boot Auto-Configuration
The component supports 5 options, which are listed below.
| Name | Description | Default | Type |
|---|---|---|---|
| camel.component.spring-batch.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.spring-batch.enabled | Whether to enable auto-configuration of the spring-batch component. This is enabled by default. | Boolean | |
| camel.component.spring-batch.job-launcher | Explicitly specifies a JobLauncher to be used. The option is a org.springframework.batch.core.launch.JobLauncher type. | JobLauncher | |
| camel.component.spring-batch.job-registry | Explicitly specifies a JobRegistry to be used. The option is a org.springframework.batch.core.configuration.JobRegistry type. | JobRegistry | |
| camel.component.spring-batch.lazy-start-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 |
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