How to Implement Spring Batch Without Database Metadata Persistence?

Is it possible to run a Spring Batch job without persistently storing metadata in a database?

// Example of a Spring Batch configuration without database persistence:
@Bean
public Job job() {
    return jobBuilderFactory.get("job")
            .start(step())
            .repository(new MapJobRepositoryFactoryBean().getObject())
            .build();
}

Spring Batch is a powerful framework for batch processing in Java, but it typically relies on persistent job metadata storage in a database. However, there are scenarios where you might want to run Spring Batch jobs without this dependency, which can be achieved using an in-memory job repository like MapJobRepository.

import org.springframework.batch.core.configuration.annotation.EnableBatchProcessing;
import org.springframework.batch.core.repository.support.MapJobRepositoryFactoryBean;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

@Configuration
@EnableBatchProcessing
public class BatchConfig {

    @Bean
    public JobRepository jobRepository() throws Exception {
        return new MapJobRepositoryFactoryBean().getObject();
    }

    @Bean
    public Job job(JobBuilderFactory jobBuilderFactory, Step step) {
        return jobBuilderFactory.get("job")
            .repository(jobRepository())
            .start(step)
            .build();
    }

    @Bean
    public Step step(StepBuilderFactory stepBuilderFactory) {
        return stepBuilderFactory.get("step")
            .tasklet((contribution, chunkContext) -> {
                System.out.println("Executing step");
                return RepeatStatus.FINISHED;
            }).build();
    }
}

Causes

• Spring Batch requires job metadata to manage job executions effectively.
• Default configuration assumes a database-backed job repository, leading to errors if none is provided.

Solutions

• Utilize `MapJobRepository` for in-memory job execution without persistence.
• Configure your Spring Batch job to use `MapJobRepository` by providing a custom job repository bean.
• Set up your job and steps as usual without referring to any database.

Mistake: Not configuring a job repository when attempting to run a batch job.

Solution: Ensure you create a `MapJobRepository` bean in your batch configuration.

Mistake: Ignoring the NullPointerException errors while executing jobs.

Solution: Check your job configuration and ensure all required beans are properly instantiated.