Decorators

Overview

Module

• package: org.eclipse.dirigible.sdk.job
• sources: Scheduled.java, JobHandler.java

A scheduled job is a @Component declared in one of two styles - never both on the same class:

• @Scheduled on a method - annotate a public no-arg method of a @Component with @Scheduled(expression = "<cron>"); the runtime invokes that method on the cron schedule.
• JobHandler - a self-describing interface (String cron() + void run()); a @Component that implements it is the job, with the cron carried by cron() and no @Scheduled needed.

Hot-reload replaces the bean transparently - the old schedule is cancelled and a new one is registered with the updated class.

Example Usage:

Method-level @Scheduled:

import org.eclipse.dirigible.sdk.component.Component;
import org.eclipse.dirigible.sdk.job.Scheduled;
import org.eclipse.dirigible.sdk.log.Logger;
import org.eclipse.dirigible.sdk.log.Logging;

@Component
public class CleanupJob {

    private static final Logger LOG = Logging.getLogger("com.acme.cleanup");

    @Scheduled(expression = "0/30 * * * * ?")
    public void cleanup() {
        LOG.info("cleanup tick");
    }
}

Self-describing JobHandler:

import org.eclipse.dirigible.sdk.component.Component;
import org.eclipse.dirigible.sdk.job.JobHandler;

@Component
public class CleanupHandler implements JobHandler {

    @Override
    public String cron() {
        return "0/30 * * * * ?";
    }

    @Override
    public void run() {
        // cleanup tick
    }
}

@Scheduled

Schedules a public no-arg method of a @Component to run on the given cron expression. It is a method-level annotation.

@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.METHOD)
public @interface Scheduled { ... }

Attributes

Attribute	Type	Description
expression	String	Quartz cron expression (six or seven fields). For example "0/30 * * * * ?" fires every 30 seconds.

Notes

• The annotated method must be public and take no arguments.
• The enclosing class must be a @Component.
• Hot-reload reinstalls the schedule when the class changes.
• For programmatic / non-cron scheduling, drop a .job JSON descriptor under the project - the Job synchronizer picks it up.

JobHandler

Self-describing contract for a job. A @Component implementing it is the scheduled job - it carries its own cron expression, so no @Scheduled annotation is involved.

public interface JobHandler {
    String cron();
    void run();
}

Notes

• cron() returns the Quartz cron expression; run() is the job body.
• Use either JobHandler or a method-level @Scheduled on a class, never both.