spring批处理：如何动态创建步骤和任务

Question

I am a spring newbie and a spring batch newbie -- so, please bear with me.

I understand that spring batch is the framework that will help run steps and tasks.

I tried using spring batch by creating steps and task using but these steps and tasks are hardcoded at program build/compile time. However, I could not figure out how to dynamically create Tasks and Steps.

What I want to do is to have a user create a script of how tasks are assembled from a list of steps. Each step will invoke a remote call to an existing REST endpoint. A task will have multiple such steps. the user will create multiple such tasks.

Is it possible to dynamically create such a task with such steps? If yes, could you point me to some sample code how to do this with the required API?

UPDATE:

I understand that a HelloWorld Job which calls a REST application using callRestApplication() looks like this.

@SpringBootApplication
@EnableBatchProcessing
public class HelloApplication {

    @Autowired
    private JobBuilderFactory jobBuilderFactory;

    @Autowired
    private StepBuilderFactory stepBuilderFactory;

    @Bean
    public Step step() {
        return this.stepBuilderFactory.get("step1")
                .tasklet((stepContribution, chunkContext) -> {
                    callRestApplication();
                    return RepeatStatus.FINISHED;
                }).build();
    }

    @Bean
    public Job job() {
        return this.jobBuilderFactory.get("HelloWorldJob")
                .start(step())
                .build();
    }

    public static void main(String[] args) {
        SpringApplication.run(HelloApplication.class, args);
    }
}

However, this is static. I was looking for a way where I can do something like this

    public static void main(String[] args) {
        SpringApplication.run(HelloagainApplication.class, args);
        List<JobDefinition> jobDefinitions = parseScript();
        for (JobDefinition jobDefinition : jobDefinitions) {
            Job job = new Job();
            job.setName(jobDefinition.getName());
            for (StepDefinition stepDefinition : jobDefinition.getStepDefinitions()) {

                Step step = new Step();
                step.setEndPoint(stepDefinition.getEndPoint());
                step.setName(stepDefinition.getName());
                step.setProperty1(stepDefinition.getProp1());
                job.addStep(step);
            }
            job.startJob();
        }
    }

If the script has 10 job definitions, then 10 jobs will be started, each with x number of steps.

In spring batch, how can I do the following

1. job.addStep(step);
2. job.startJob();

Thanks

Answer 1

There is no such feature in Spring Batch. You need to write custom code that parses your user's script and create job/step definitions accordingly.

That said, Spring Cloud Dataflow might help you. You can pre-define your tasks and let the user compose them using the GUI or the text-based scriptable DSL. Another feature that could be interesting to you is the single-step job starter from Spring Cloud Task, which allows you to dynamically create a single-step job by providing some properties (no coding needed).