Using JSL Inheritance with JBeret

In practical use, many boilerplate code will appear to Job definition XMLs of JSR352 batch such as definition of Listeners, Properties and attribute such as item-count of chunk element. to overcome this, there is the specification of JSL Inheritance but it deferred to next version of JBatch spec but JBeret supports this specification already. it’s very useful to eliminate annoying fragments appear repeatedly so I tested it. WildFly 8.2.0.Final was used for test.

The project which used to the test is available in my GitHub repository.

Parent XML

Parent XML begins as follows:

<?xml version="1.0" encoding="UTF-8"?>
<job id="parent" abstract="true" version="1.0" xmlns="http://xmlns.jcp.org/xml/ns/javaee">

    <properties>
        <property name="someJobProp" value="someJobPropValue"/>
    </properties>

    <listeners>
        <listener ref="myJobListener"/>
    </listeners>

Declared property named someJobProp become visible from child XMLs. myJobListener will be included implicitly in child XMLs as well.

Parent XML has an abstract step element which will be referenced from child XMLs as follows. these properties and listeners for a step will be included implicitly too. we can override javax.transaction.global.timeout at there. it will be affected to all of child steps.

    <step id="mySimpleStep" abstract="true">
        <properties>
            <property name="javax.transaction.global.timeout" value="1800"/>
        </properties>
        <listeners>
            <listener ref="myStepListener"/>
        </listeners>
    </step>

It is the same for chunk based step. it can be used to eliminate defining item-count for all of chunk steps.

    <step id="myChunkStep" abstract="true">
        <properties>
            <property name="javax.transaction.global.timeout" value="900"/>
            <property name="jberet.local-tx" value="true"/>
        </properties>
        <listeners>
            <listener ref="myStepListener"/>
            <listener ref="myChunkListener"/>
        </listeners>
        <chunk item-count="3"/>
    </step>

</job>

Child XML

Child XML became very simple thanks to inheritance as follows. you need to specify parent and jsl-name attributes to reference its parent. parent means the name of parent attribute. jsl-name means XML file name of referencing element.

<?xml version="1.0" encoding="UTF-8"?>
<job id="child" parent="parent" jsl-name="parent" version="1.0" xmlns="http://xmlns.jcp.org/xml/ns/javaee">

    <step id="simpleStep" next="chunkStep" parent="mySimpleStep" jsl-name="parent">
        <batchlet ref="myBatchlet"/>
    </step>

    <step id="chunkStep" parent="myChunkStep" jsl-name="parent">
        <chunk>
            <reader ref="myItemReader"/>
            <writer ref="myItemWriter"/>
        </chunk>
    </step>

</job>

Launching example job

Clone the repository
Build the WAR and deploy it to your WildFly
Run a JUnit test class named JobTest. it invokes the job through remote EJB invocation.

Log

You can see Properties, Listeners and item-count attribute were inherited as expected.

(Batch Thread - 1) Job child starting
(Batch Thread - 1) Job child, Step simpleStep starting
(Batch Thread - 1) hello world!
(Batch Thread - 1) jobProps: {someJobProp=someJobPropValue}
(Batch Thread - 1) stepProps: {javax.transaction.global.timeout=1800}
(Batch Thread - 1) Job child, Step simpleStep done
(Batch Thread - 1) Job child, Step chunkStep starting
(Batch Thread - 1) jobProps: {someJobProp=someJobPropValue}
(Batch Thread - 1) stepProps: {jberet.local-tx=true, javax.transaction.global.timeout=900}
(Batch Thread - 1) Job child, Step chunkStep chunk starting
(Batch Thread - 1) write: [1, 2, 3]
(Batch Thread - 1) Job child, Step chunkStep chunk done
(Batch Thread - 1) Job child, Step chunkStep chunk starting
(Batch Thread - 1) write: [4, 5, 6]
(Batch Thread - 1) Job child, Step chunkStep chunk done
(Batch Thread - 1) Job child, Step chunkStep chunk starting
(Batch Thread - 1) write: [7, 8, 9]
(Batch Thread - 1) Job child, Step chunkStep chunk done
(Batch Thread - 1) Job child, Step chunkStep chunk starting
(Batch Thread - 1) write: [0]
(Batch Thread - 1) Job child, Step chunkStep chunk done
(Batch Thread - 1) Job child, Step chunkStep done
(Batch Thread - 1) Job child done

Kohei Nozaki's blog