CDI not working with Java EE Batch under jberet implementation

Question

I have a Java EE batch application implemented with jberet deployed on WildFly application server. This application also expose a REST api to trigger a job on demand.

I have following class creating beans to be injected:

public class Factory {

    @Produces
    public JsonValidator getJsonValidator() {
        return JsonSchemaFactory.byDefault().getValidator();
}

Injecting the above bean in the REST api works fine:

@Path("my-resource")
public class MyResource{

    @Inject
    private JsonValidator jsonValidator;

    @PUT
    @Consumes(MediaType.APPLICATION_JSON)
    public Response handleNotification(String notification) {
        // using jsonValidator here works fine..

However using the same bean in ItemReader throws a null pointer exception however injecting JobContext works without any issue:

public class MyReader extends AbstractItemReader {

    @Inject
    private JobContext jobContext;

    @Inject
    private JsonValidator jsonValidator;

    @Override
    public Integer readItem() throws Exception {
        // using jsonValidator here throws a null pointer exception
        // however jobContext works fine

My beans.xml under src/main/resources/META-INF:

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://xmlns.jcp.org/xml/ns/javaee"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/beans_1_1.xsd"
       version="1.1" bean-discovery-mode="all">
</beans>

job file under src/main/resources/META-INF/batch-jobs/myjob.xml:

<job id="myjob" xmlns="http://xmlns.jcp.org/xml/ns/javaee" version="1.0"> 
  <step id="mystep">
    <chunk item-count="1">
      <reader ref="myReader"/>
      <processor ref="myProcessor"/>
      <writer ref="myWriter"/>
    </chunk>
  </step>
</job>

batch artifacts file under src/main/resources/META-INF/batch.xml

<?xml version="1.0" encoding="UTF-8"?>
<batch-artifacts xmlns="http://xmlns.jcp.org/xml/ns/javaee">
    <ref id="myReader" class="com.my.app.MyReader" />
    <ref id="myProcessor" class="com.my.app.MyProcessor" />
    <ref id="myWriter" class="com.my.app.MyWriter" />
</batch-artifacts>

My pom.xml looks as below:

<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.my.app</groupId>
    <artifactIdjava-batch</artifactId>
    <packaging>war</packaging>
    <version>1.0</version>

    <name>java-batch</name>
    <url>http://maven.apache.org</url>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>

        <!-- JBoss dependency versions -->
        <version.wildfly.maven.plugin>1.0.2.Final</version.wildfly.maven.plugin>

        <!-- other plugin versions -->
        <version.compiler.plugin>3.7.0</version.compiler.plugin>
        <version.surefire.plugin>2.21.0</version.surefire.plugin>
        <version.war.plugin>3.2.0</version.war.plugin>

        <!-- maven-compiler-plugin -->
        <maven.compiler.target>1.8</maven.compiler.target>
        <maven.compiler.source>1.8</maven.compiler.source>

        <version.org.jboss.spec.javax.batch.jboss-batch-api_1.0_spec>1.0.0.Final
        </version.org.jboss.spec.javax.batch.jboss-batch-api_1.0_spec>
        <version.org.jboss.spec.javax.ws.rs.jboss-jaxrs-api_2.0_spec>1.0.0.Final</version.org.jboss.spec.javax.ws.rs.jboss-jaxrs-api_2.0_spec>
        <version.org.jberet>1.3.0.Final</version.org.jberet>
        <version.javax.inject>1</version.javax.inject>
        <version.javax.enterprise>2.0</version.javax.enterprise>
    </properties>

    <build>
        <finalName>java-batch</finalName>
        <plugins>
            <plugin>
                <artifactId>maven-war-plugin</artifactId>
                <version>${version.war.plugin}</version>
            </plugin>
        </plugins>
    </build>

    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.jboss.spec.javax.batch</groupId>
                <artifactId>jboss-batch-api_1.0_spec</artifactId>
                <version>${version.org.jboss.spec.javax.batch.jboss-batch-api_1.0_spec}</version>
                <scope>provided</scope>
            </dependency>
            <dependency>
                <groupId>javax.inject</groupId>
                <artifactId>javax.inject</artifactId>
                <version>${version.javax.inject}</version>
                <scope>provided</scope>
            </dependency>
            <dependency>
                <groupId>javax.enterprise</groupId>
                <artifactId>cdi-api</artifactId>
                <version>${version.javax.enterprise}</version>
                <scope>provided</scope>
            </dependency>

            <dependency>
                <groupId>org.jberet</groupId>
                <artifactId>jberet-rest-api</artifactId>
                <version>${version.org.jberet}</version>
                <scope>runtime</scope>
            </dependency>
            <dependency>
                <groupId>org.jberet</groupId>
                <artifactId>jberet-rest-commons</artifactId>
                <version>${version.org.jberet}</version>
                <scope>runtime</scope>
                <exclusions>
                    <exclusion>
                        <groupId>org.jberet</groupId>
                        <artifactId>jberet-core</artifactId>
                    </exclusion>
                </exclusions>
            </dependency>
            <dependency>
                <groupId>org.jberet</groupId>
                <artifactId>jberet-schedule-executor</artifactId>
                <version>${version.org.jberet}</version>
                <scope>runtime</scope>
            </dependency>
            <dependency>
                <groupId>org.jberet</groupId>
                <artifactId>jberet-schedule-timer</artifactId>
                <version>${version.org.jberet}</version>
                <scope>runtime</scope>
            </dependency>
            <dependency>
                <groupId>org.jberet</groupId>
                <artifactId>jberet-support</artifactId>
                <version>${version.org.jberet}</version>
                <scope>runtime</scope>
            </dependency>
            <dependency>
                <groupId>org.jboss.spec.javax.ws.rs</groupId>
                <artifactId>jboss-jaxrs-api_2.0_spec</artifactId>
                <version>${version.org.jboss.spec.javax.ws.rs.jboss-jaxrs-api_2.0_spec}</version>
            </dependency>
        </dependencies>
    </dependencyManagement>

    <dependencies>
        <dependency>
            <groupId>org.jboss.spec.javax.batch</groupId>
            <artifactId>jboss-batch-api_1.0_spec</artifactId>
        </dependency>
        <dependency>
            <groupId>javax.inject</groupId>
            <artifactId>javax.inject</artifactId>
        </dependency>
        <dependency>
            <groupId>javax.enterprise</groupId>
            <artifactId>cdi-api</artifactId>
        </dependency>

        <dependency>
            <groupId>org.jberet</groupId>
            <artifactId>jberet-rest-api</artifactId>
        </dependency>
        <dependency>
            <groupId>org.jberet</groupId>
            <artifactId>jberet-rest-commons</artifactId>
        </dependency>
        <dependency>
            <groupId>org.jberet</groupId>
            <artifactId>jberet-schedule-executor</artifactId>
        </dependency>
        <dependency>
            <groupId>org.jberet</groupId>
            <artifactId>jberet-schedule-timer</artifactId>
        </dependency>
        <dependency>
            <groupId>org.jberet</groupId>
            <artifactId>jberet-support</artifactId>
        </dependency>
        <dependency>
            <groupId>org.jberet</groupId>
            <artifactId>jberet-core</artifactId>
            <version>${version.org.jberet}</version>
        </dependency>
        <dependency>
            <groupId>org.jboss.spec.javax.ws.rs</groupId>
            <artifactId>jboss-jaxrs-api_2.0_spec</artifactId>
        </dependency>

        <dependency>
            <groupId>com.github.fge</groupId>
            <artifactId>json-schema-validator</artifactId>
            <version>2.2.6</version>
        </dependency>
        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-databind</artifactId>
            <version>LATEST</version>
            <scope>compile</scope>
        </dependency>

    </dependencies>
</project>

I have tried various combination of @Produce, @JobScoped (org.jberet.cdi.JobScoped) and injecting an annotated Class with @JobScoped, @Default and @ApplicationScoped but all produce the same result (NullPointerException while using the injected object).

What am I missing?

`JsonValidator` is not container-managed, and your `MyReader` class is not managed by the Jackson context that knows how to provide it. You need to manually add a bean to resolve it there... — BadZen, Apr 17 '19 at 12:18
@Produces on getJsonValidator() under Factory class should make it a manage bean. It is injecting as expected with MyResource but not with MyReader. — adesai, Apr 17 '19 at 12:42

score 2 · Accepted Answer · answered Apr 17 '19 at 13:58

2

Try adding @Named to your reader, processor and writer classes, and removing src/main/resources/META-INF/batch.xml. This will let CDI to discover batch artifacts as CDI beans and perform dependency injection.

answered Apr 17 '19 at 13:58

cheng

1,076
6
6

I have updated src/main/resources/META-INF/batch-jobs/myjob.xml with full class refs. and removed the file src/main/resources/META-INF/batch.xml. Also added @Named (and tried with @Named("MyReader")...) to the MyReader class and so on. It didn't work :( – adesai Apr 17 '19 at 14:27
1

If you want to use cdi injection, you should not use batch.xml to define batch artifacts, nor use class name to define them in job.xml. If you still see errors, please file an issue at https://issues.jboss.org/browse/WFLY-11906?jql=project%20%3D%20WFLY%20AND%20component%20%3D%20Batch with a reproducer and I will take a closer look. – cheng Apr 17 '19 at 14:40
I have updated myjob.xml with ref name mentioned in @Named rather than full class name and it works :) Thanks Cheng – adesai Apr 17 '19 at 14:49

CDI not working with Java EE Batch under jberet implementation

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