quartz

The main goal of this project is to explore basic features of Quartz - job scheduler.

preface

Job scheduler is a service component that is responsible for executing (or notifying) other software components when a pre-determined (scheduled) time arrives.

definition

Quartz is a job scheduling library that can be integrated with, or used along side virtually any other software system.

Quartz is very light-weight, and requires very little setup/configuration.

pros

• open source,
• support for JTA: Quartz can manage JTA transactions (begin and commit them) around the execution of a Job, so that the work performed by the Job automatically happens within a JTA transaction,
• support for clustering (useful for load balancing),
• JDBCJobStore - all Jobs and Triggers configured as “non-volatile” are stored in a relational database via JDBC,
• RAMJobStore - ll Jobs and Triggers are stored in RAM and therefore do not persist between program executions - but this has the advantage of not requiring an external database.

manual

• pom.xml

  <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-quartz</artifactId>
  </dependency>
  

• quartz job (SampleJob.java)

  1. Inherit QuartzJobBean

     SampleJob extends QuartzJobBean
     

  2. Implement executeInternal(JobExecutionContext context)

     @Override
     protected void executeInternal(JobExecutionContext context) {
         System.out.println("SampleJob invoked!");
     }
     

• produce job as a JobDetail (JobProducer.java)

  @Bean
  @SampleJobDetail
  public JobDetail sampleJobDetail() {
      return JobBuilder
              .newJob(SampleJob.class)
              .storeDurably()
              .build();
  }
  

• bind trigger to the job detail (TriggerProducer.java)

  @Bean
  public Trigger sampleJobTrigger(@SampleJobDetail JobDetail jobDetail) {
      SimpleScheduleBuilder scheduleBuilder = ...
  
      return TriggerBuilder
              .newTrigger()
              .forJob(jobDetail)
              .withSchedule(scheduleBuilder)
              .build();
  }
  

  where scheduleBuilder is for example:

  SimpleScheduleBuilder scheduleBuilder = SimpleScheduleBuilder
                  .simpleSchedule()
                  .withIntervalInSeconds(2)
                  .repeatForever();