Payara for Beginners - a Simple JBatch Schedule

Firstly, we need to create a java class that appends the current datetime to a file.
JBatch implement two variations of Job step: Chunks - which are built around the traditional batch process of reader, processor and writer elements – and Batchlets for simple tasks.
For the simple process appending a datetime to a file we will be using a Batchlet.To correctly implement a Batchlet we must define process() and stop() methods.

@Dependent
@Named("TestBatchlet")
public class TestBatchlet implements Batchlet {

    @Inject
    private JobContext jobCtx;

    @Override
    public String process() throws Exception {
        String filename = jobCtx.getProperties().getProperty("outfile");
        String timestamp = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").format(new Date());

        BufferedWriter output = new BufferedWriter(new FileWriter(filename, true));
        output.append(timestamp);
        output.newLine();
        output.close();

        return "COMPLETED";
    }

    @Override
    public void stop() throws Exception {
    }
}

Next, we need to define the steps that make-up our batch job using the Job Specification Language (JSL). The below JSL defines our single-step job and also the value of the outfile property used by the Batchlet.The JSL must be held in an XML file located in the META-INF/batch-jobs directory.

BatchTest.xml



<?xml version="1.0" encoding="UTF-8"?>
<job id="testjob" xmlns="http://xmlns.jcp.org/xml/ns/javaee" version="1.0">
    <properties>
        <property name="outfile" value="\tmp\output.txt"/>
    </properties>
    <step id="teststep">
        <batchlet ref="TestBatchlet"/>
    </step>
</job>

Finally, we will create an EJB to trigger our job every 30 seconds

@Stateless
public class TestSchedule {

    @Schedule(second = "*/30", minute = "*", hour = "*") // Thirty second intervals
    public void processFiles() {
        JobOperator jobOperator = BatchRuntime.getJobOperator();
        jobOperator.start("BatchTest", null);
    }
}

Deploying the above will append the current datetime to the file specified in the XML at 30 second intervals:

2015-12-21 15:06:00
2015-12-21 15:06:30
2015-12-21 15:07:00
2015-12-21 15:07:30
2015-12-21 15:08:00
2015-12-21 15:08:30

And this is all that is required to implement the most basic batch process!

Want to learn more about JBatch? Check out Batch Applications in Java EE 7 - Undertanding JSR 352 Concepts article by Arun Gupta on the GlassFish blog; or watch the 'Batch Applications for the Java Platform 1.0' video by Chris Vignola.