Spring Batch RabbitMQ issue

Question

I am looking to integrate the Spring Batch with RabbitMQ. I've developed code like below but no data is passing over the channel. What's wrong in the code?

CustomerMessageChannel.java

public interface CustomerMessageChannel {
    @Output("customerMessageChannel")
    MessageChannel customerMessageChannel();
}

Customer.java

@AllArgsConstructor
@NoArgsConstructor
@Builder
@Data
@JsonIgnoreProperties(ignoreUnknown = true)
public class Customer implements Serializable {
    private static final long serialVersionUID = 1L;
    private Long id;
    private String firstName;
    private String lastName;
    private String birthdate;
}

CustomerFieldSetMapper.java

public class CustomerFieldSetMapper implements FieldSetMapper<Customer> {
    
    @Override
    public Customer mapFieldSet(FieldSet fieldSet) throws BindException {
        return Customer.builder()
                .id(fieldSet.readLong("id"))
                .firstName(fieldSet.readRawString("firstName"))
                .lastName(fieldSet.readRawString("lastName"))
                .birthdate(fieldSet.readRawString("birthdate"))
                .build();
    }

}

JobConfig.java

@Configuration
public class JobConfig {

    @Autowired
    private StepBuilderFactory stepBuilderFactory;

    @Autowired
    private JobBuilderFactory jobBuilderFactory;
    
    @Autowired
    private AmqpTemplate amqpTemplate;

    @Bean
    public FlatFileItemReader<Customer> customerItemReader() {
        FlatFileItemReader<Customer> reader = new FlatFileItemReader<>();
        reader.setLinesToSkip(1);
        reader.setResource(new ClassPathResource("/data/customer.csv"));

        DelimitedLineTokenizer tokenizer = new DelimitedLineTokenizer();
        tokenizer.setNames(new String[] { "id", "firstName", "lastName", "birthdate" });

        DefaultLineMapper<Customer> customerLineMapper = new DefaultLineMapper<>();
        customerLineMapper.setLineTokenizer(tokenizer);
        customerLineMapper.setFieldSetMapper(new CustomerFieldSetMapper());
        customerLineMapper.afterPropertiesSet();

        reader.setLineMapper(customerLineMapper);

        return reader;
    }
    
    @Bean
    public AmqpItemWriter<Customer> amqpItemWriter() throws Exception{
        return new AmqpItemWriter<>(amqpTemplate);
    }
        
    @Bean
    public Step step1() throws Exception {
        return stepBuilderFactory.get("step1")
                .<Customer, Customer>chunk(10)
                .reader(customerItemReader())
                .writer(amqpItemWriter())
                .build();
    }
    
    @Bean
    public Job job() throws Exception {
        return jobBuilderFactory.get("job")
                .incrementer(new RunIdIncrementer())
                .start(step1())
                .build();
    }
}

application.properties

spring.rabbitmq.host=localhost
spring.rabbitmq.port=5672
spring.rabbitmq.username=guest
spring.rabbitmq.password=guest

spring.cloud.stream.bindings.customerMessageChannel.destination=customerMessageChannel
spring.cloud.stream.default.contentType=application/json

customer.csv

id,firstName,lastName,
1, John, Doe,10-10-1952 10:10:10
2, Amy, Eugene,05-07-1985 17:10:00
3, Laverne, Mann,11-12-1988 10:10:10
4, Janice, Preston,19-02-1960 10:10:10
5, Pauline, Rios,29-08-1977 10:10:10
6, Perry, Burnside,10-03-1981 10:10:10
7, Todd, Kinsey,14-12-1998 10:10:10
8, Jacqueline, Hyde,20-03-1983 10:10:10
9, Rico, Hale,10-10-2000 10:10:10
10, Samuel, Lamm,11-11-1999 10:10:10
11, Robert, Coster,10-10-1972 10:10:10
12, Tamara, Soler,02-01-1978 10:10:10
13, Justin, Kramer,19-11-1951 10:10:10
14, Andrea, Law,14-10-1959 10:10:10
15, Laura, Porter,12-12-2010 10:10:10
16, Michael, Cantu,11-04-1999 10:10:10
17, Andrew, Thomas,04-05-1967 10:10:10
18, Jose, Hannah,16-09-1950 10:10:10
19, Valerie, Hilbert,13-06-1966 10:10:10
20, Patrick, Durham,12-10-1978 10:10:10

SpringBatchAmqpApplication.java

@EnableBatchProcessing
@SpringBootApplication
public class SpringBatchAmqpApplication {

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

}

Answer 1

You need to configure an exchange and routing key for the template - by default, RabbitMQ will discard unroutable messages.

https://docs.spring.io/spring-boot/docs/current/reference/html/appendix-application-properties.html#spring.rabbitmq.template.exchange https://docs.spring.io/spring-boot/docs/current/reference/html/appendix-application-properties.html#spring.rabbitmq.template.routing-key

You also don't seem to be referencing customerMessageChannel any place so it's not clear what you are expecting.

To consume from the spring-cloud-stream destination, you need @EnableBinding(CustomerMessageChannel.class) and a @StreamListener method. However, that annotation model is now deprecated in favor of the functional programming model.

https://docs.spring.io/spring-cloud-stream/docs/3.1.0/reference/html/spring-cloud-stream.html#spring-cloud-stream-overview-producing-consuming-messages