JavaEE Sample::Batch::Batch Chunk Simple

ChunkSimpleTest

The Batch specification provides a Chunk Oriented processing style. This style is defined by enclosing into a transaction a set of reads, process and write operations via ItemReader, ItemProcessor and ItemWriter. Items are read one at a time, processed and aggregated. The transaction is then committed when the defined checkpoint-policy is triggered.

<?xml version="1.0" encoding="UTF-8"?>
<job id="myJob" xmlns="http://xmlns.jcp.org/xml/ns/javaee" version="1.0">
    <step id="myStep" >
        <chunk item-count="3">
            <reader ref="myItemReader"/>
            <processor ref="myItemProcessor"/>
            <writer ref="myItemWriter"/>
        </chunk>
    </step>
</job>

A very simple job is defined in the myJob.xml file. Just a single step with a reader, a processor and a writer.

We’re just going to deploy the application as a web archive. Note the inclusion of the following files:

/META-INF/batch-jobs/myJob.xml

The myJob.xml file is needed for running the batch definition.

@Deployment
public static WebArchive createDeployment() {
    WebArchive war = ShrinkWrap.create(WebArchive.class)
            .addClass(BatchTestHelper.class)
            .addPackage("org.javaee7.batch.chunk.simple")
            .addAsWebInfResource(EmptyAsset.INSTANCE, ArchivePaths.create("beans.xml"))
            .addAsResource("META-INF/batch-jobs/myJob.xml");
    System.out.println(war.toString(true));
    return war;
}

In the test, we’re just going to invoke the batch execution and wait for completion. To validate the test expected behaviour we need to query the Metric object available in the step execution.

The batch process itself will read and process 10 elements from numbers 1 to 10, but only write the odd elements. Commits are executed after 3 elements are read.

@Test
public void testChunkSimple() throws Exception {
    JobOperator jobOperator = BatchRuntime.getJobOperator();
    Long executionId = jobOperator.start("myJob", new Properties());
    JobExecution jobExecution = jobOperator.getJobExecution(executionId);

    jobExecution = BatchTestHelper.keepTestAlive(jobExecution);

    List<StepExecution> stepExecutions = jobOperator.getStepExecutions(executionId);
    for (StepExecution stepExecution : stepExecutions) {
        if (stepExecution.getStepName().equals("myStep")) {
            Map<Metric.MetricType, Long> metricsMap = BatchTestHelper.getMetricsMap(stepExecution.getMetrics());

            (1)
            assertEquals(10L, metricsMap.get(Metric.MetricType.READ_COUNT).longValue());
            (2)
            assertEquals(10L / 2L, metricsMap.get(Metric.MetricType.WRITE_COUNT).longValue());
            (3)
            assertEquals(10L / 3 + (10L % 3 > 0 ? 1 : 0),
                         metricsMap.get(Metric.MetricType.COMMIT_COUNT).longValue());
        }
    }

    (4)
    assertEquals(jobExecution.getBatchStatus(), BatchStatus.COMPLETED);
}

The read count should be 10 elements. Check MyItemReader.
The write count should be 5. Only half of the elements read are processed to be written.
The commit count should be 4. Checkpoint is on every 3rd read, 4 commits for read elements.
Job should be completed.

Batch Chunk Simple

Chunk Processing - Read, Process, Write

ChunkSimpleTest

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