Now that a process engine is available, we model a small loan approval process with a service task that invokes a Spring bean.

Model the Process

Using the Camunda Modeler, we model loanApproval.bpmn: a start event, a service task that invokes a Spring bean via a camunda:delegateExpression, and an end event:

<bpmn2:serviceTask id="ServiceTask_1" name="Calculate&#10;Interest" camunda:delegateExpression="${calculateInterestService}">

Implement the Service Task

CalculateInterestService is a plain JavaDelegate:

public class CalculateInterestService implements JavaDelegate {

  public void execute(DelegateExecution delegate) {
    System.out.println("Spring Bean invoked");
  }

}

Register the Beans and Deploy the Process

We register CalculateInterestService as a Spring bean, add a Starter bean that starts a loanApproval process instance as soon as the Spring context has fully initialized, and tell the process engine configuration to deploy every BPMN file found on the classpath:

@Bean
public SpringProcessEngineConfiguration engineConfiguration(
    DataSource dataSource,
    PlatformTransactionManager transactionManager,
    @Value("classpath*:*.bpmn") Resource[] deploymentResources) {
  SpringProcessEngineConfiguration configuration = new SpringProcessEngineConfiguration();

  configuration.setProcessEngineName("engine");
  configuration.setDataSource(dataSource);
  configuration.setTransactionManager(transactionManager);
  configuration.setDatabaseSchemaUpdate("true");
  configuration.setJobExecutorActivate(false);
  configuration.setDeploymentResources(deploymentResources);

  return configuration;
}

@Bean
public Starter starter() {
  return new Starter();
}

@Bean
public CalculateInterestService calculateInterestService() {
  return new CalculateInterestService();
}

Starter starts the process as soon as the application context is ready:

public class Starter implements InitializingBean {

  @Autowired
  private RuntimeService runtimeService;

  public void afterPropertiesSet() throws Exception {
    runtimeService.startProcessInstanceByKey("loanApproval");
  }

}

Build and Run

Rebuild and redeploy the WAR file. Deploying the application now automatically starts a loanApproval process instance, which invokes the Spring-managed CalculateInterestService bean - check the container log for Spring Bean invoked.