Dkron Scheduler Adapter Library for Spring Boot

The Dkron Scheduler Adapter Library is a user-friendly Spring Boot library, designed as an adapter for the Dkron tool. This library provides convenient job scheduling and execution capabilities within your Spring Boot applications.

Installation

• To integrate the Dkron Scheduler Client Adapter Library in your Spring Boot project add to gradle

TODO :)

• Eventually configure properties

Configuration properties

• scheduler.dkron-server-url : URL of the dkron server
  • default : http://localhost:8081
  • (if you are running dkron server on docker remember to map 8080 to 8081,the default port configuration has been changed because it is the default one for the Spring application.)
• scheduler.dkron-rest-api-retry-attempts : Number of attempts to retry the rest api call to dkron server
  • default : 3
• scheduler.dkron-rest-api-minimum-backoff-in-milliseconds : Minimum backoff time in milliseconds between retries
  • default : 250
• scheduler.job-execution-server-url : URL of the job execution server, in other words URL of application in network, so that dkron can find it and execute the job.
  • default : http://localhost:8080

Usage

Scheduling job

To schedule jobs, use the JobScheduler bean and pass an instance of JobDescription to it. Here's a concise example of scheduling a job,

@Component
@RequiredArgsConstructor
class SchedulingExample {
    private final JobScheduler jobScheduler;

    void scheduleJob() {
        String id = UUID.randomUUID().toString();
        JobDescription jobDescription = new JobDescription(
                id,
                new PrintSomethingJobDto("Job %s execution".formatted(id)),
                new Schedule.Fixed(Instant.now().plus(Duration.ofSeconds(5)))
        );
        jobScheduler.scheduleJob(jobDescription);
    }

}

additional information about JobDescription

jobNotificationPayload: A POJO (Plain Old Java Object) containing additional information sent as part of the job execution notification. This object can be any DTO but must adhere to the POJO structure, containing a no-args constructor, getters, and setters.

Handling Job Executions

Default Notification Publisher

By default, this library uses Spring Boot’s event publisher for notifying about job executions. To handle these notifications, create a method annotated with @EventListener and listen for the object passed to JobDescription.

@Component
@Slf4j
class JobExecutionListener {
    @EventListener
    public void execute(PrintSomethingJobDto printSomethingJobDto) {
        log.info("PrintSomething job executed: {}", printSomethingJobDto);
    }
}

Custom Notification Handling

For custom implementations, provide your own implementation of JobExecutionNotifier.

Testing

There is also test tool library for testing pojo compatibility.

// TODO

Example

import com.codibly.schedulerclient.JobNotificationPayloadCompatibilityChecker;
import org.junit.jupiter.api.Test;

class PojoCompatibilityTest {
    
    @Test
    void  checkIfPojoIsCompatibleWithDkronScheduler(){
        // Given
        PrintSomethingJobDto helloWorld = new PrintSomethingJobDto("Hello World");

        // Then
        JobNotificationPayloadCompatibilityChecker.of(helloWorld).verifySerializationCompatibility();
    }
}

Submodules

dkron-scheduler-client

Main submodule with scheduler client implementation

dkron-scheduler-client-test-tool

Submodule with test tool for dkron-scheduler-client

example-usage

Submodule with example usage of dkron-scheduler-client