Storing Job Repository in In-Memory datastore

In this post under Spring Batch, I will explain what is the purpose of Job Repository in Spring Batch and how to store it in In-Memory datastore.

Job Repository is used to store the state of a Job (finished or currently executing). In other words Job Repository stores all the metadata of a Job. Informations
such as list of executed steps, how many items read, wrote, or skipped, the duration of each step etc. Job repository can be stored in in-memory or in database.

To store the job repository in in-memory, below is the xml configuration

XML Configuration


1 <bean id="transactionManager" class="org.springframework.batch.support.transaction.ResourcelessTransactionManager" />
2 
3 <bean id="jobRepository" class="org.springframework.batch.core.repository.support.MapJobRepositoryFactoryBean">
4   <property name="transactionManager" ref="transactionManager"/>
5 </bean>
6 
7 <bean id="jobLauncher" class="org.springframework.batch.core.launch.support.SimpleJobLauncher">
8   <property name="jobRepository" ref="jobRepository"/>
9 </bean>

As shown in above xml line 3, we need to create an instance of MapJobRepositoryFactoryBean with id “jobRepository”. MapJobRepositoryFactoryBean, a factory bean creates an instance of SimpleJobRepository, which stores metadata in in-memory datastore.

Next we inform the JobLauncher to use the in-memory datastore with id “jobRepository”. Refer to line 8.

The jobRepository instance need a transaction manager. So we create a instance of ResourcelessTransactionManager at line 1 and set it to jobRepository instance at line 4.

In this way we create job repository that will be stored in in-memory datastore. This is useful for testing or when monitoring or restart capabilities is not needed.

Below is the complete xml configuration


<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:batch="http://www.springframework.org/schema/batch"
    xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
                        http://www.springframework.org/schema/batch http://www.springframework.org/schema/batch/spring-batch.xsd">
    
    <bean id="employee" class="package1.Employee" scope="prototype"/>
    
    <bean id="reader" class="org.springframework.batch.item.file.FlatFileItemReader">
        <property name="resource" value="file:FileInput.txt"/>
        <property name="lineMapper">
            <bean class="org.springframework.batch.item.file.mapping.DefaultLineMapper">
                <property name="lineTokenizer">
                    <bean class="org.springframework.batch.item.file.transform.DelimitedLineTokenizer">
                        <property name="names" value="id,name,status,salary"/>
                    </bean>
                </property>
                <property name="fieldSetMapper">
                    <bean class="org.springframework.batch.item.file.mapping.BeanWrapperFieldSetMapper">
                        <property name="prototypeBeanName" value="employee"/>
                    </bean>
                </property>
            </bean>
        </property> 
    </bean>
    
    <bean id="writer" class="org.springframework.batch.item.file.FlatFileItemWriter">
        <property name="resource" value="file:FileOutput.txt"/>
        <property name="lineAggregator">
            <bean class="org.springframework.batch.item.file.transform.DelimitedLineAggregator">
                <property name="fieldExtractor">
                    <bean class="org.springframework.batch.item.file.transform.BeanWrapperFieldExtractor">
                        <property name="names" value="id,name,status,salary"/>
                    </bean>
                </property>
            </bean>
        </property>
    </bean>
    
    <batch:job id="importEmployees">
        <batch:step id="readWriteEmployees">
            <batch:tasklet>
                <batch:chunk reader="reader" writer="writer" commit-interval="50"/>
            </batch:tasklet>
        </batch:step>
    </batch:job>
    
    <bean id="transactionManager" class="org.springframework.batch.support.transaction.ResourcelessTransactionManager" />
    
    <bean id="jobRepository" class="org.springframework.batch.core.repository.support.MapJobRepositoryFactoryBean">
        <property name="transactionManager" ref="transactionManager"/>
    </bean>
    
    <bean id="jobLauncher" class="org.springframework.batch.core.launch.support.SimpleJobLauncher">
        <property name="jobRepository" ref="jobRepository"/>
    </bean>
</beans>
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