Notification Service

notifications/
  Tasks.java     # one task per channel + payload records
  Service.java   # the producer API the rest of the app calls
  WorkerMain.java # the worker process

import java.time.Duration;
import org.byteveda.flexiq.task.RetryPolicy;
import org.byteveda.flexiq.task.Task;

public final class Tasks {
    public record Email(String to, String subject, String body) {}
    public record Sms(String to, String text) {}

    public static final Task<Email> SEND_EMAIL = Task.of("send_email", Email.class)
            .maxRetries(5)
            .retryPolicy(RetryPolicy.exponential(Duration.ofSeconds(2), Duration.ofMinutes(5)));

    public static final Task<Sms> SEND_SMS = Task.of("send_sms", Sms.class)
            .maxRetries(3);

    public static final Task<String> SEND_DIGEST = Task.of("send_digest", String.class);

    private Tasks() {}
}

import java.time.Duration;
import java.util.List;
import org.byteveda.flexiq.FlexiQ;
import org.byteveda.flexiq.model.JobFilter;
import org.byteveda.flexiq.model.JobStatus;
import org.byteveda.flexiq.task.EnqueueOptions;

public final class Service {
    private final FlexiQ flexiq;

    public Service(FlexiQ flexiq) {
        this.flexiq = flexiq;
    }

    // 1. Delayed scheduling — remind 24h from now.
    public String scheduleReminder(String email) {
        return flexiq.enqueue(Tasks.SEND_EMAIL, new Tasks.Email(email, "Reminder", "..."),
                EnqueueOptions.builder().delay(Duration.ofHours(24)).build());
    }

    // 2. Idempotency — a duplicate enqueue with the same key is a no-op while
    //    the first is still pending or running.
    public String sendWelcomeOnce(String userId, String email) {
        return flexiq.enqueue(Tasks.SEND_EMAIL, new Tasks.Email(email, "Welcome", "..."),
                EnqueueOptions.builder().uniqueKey("welcome:" + userId).build());
    }

    // 3. Priority — security alerts preempt routine mail.
    public String sendSecurityAlert(String phone, String text) {
        return flexiq.enqueue(Tasks.SEND_SMS, new Tasks.Sms(phone, text),
                EnqueueOptions.builder().priority(100).build());
    }

    // 4. Batch fan-out — stage a whole digest run in one storage call.
    public List<String> sendDigests(List<Tasks.Email> due) {
        return flexiq.enqueueMany(Tasks.SEND_EMAIL, due);
    }

    // 5. Cancellation — pull a not-yet-started send.
    public boolean cancelScheduled(String jobId) {
        return flexiq.cancel(jobId); // false if it already started
    }

    // 6. Inspection — what's still pending?
    public List<org.byteveda.flexiq.model.Job> pendingSends() {
        return flexiq.listJobs(JobFilter.builder()
                .status(JobStatus.PENDING)
                .task("send_email")
                .limit(50)
                .build());
    }
}

import java.util.List;
import org.byteveda.flexiq.FlexiQ;
import org.byteveda.flexiq.scheduling.PeriodicTask;
import org.byteveda.flexiq.worker.Worker;

public final class WorkerMain {
    public static void main(String[] args) throws InterruptedException {
        try (FlexiQ flexiq = FlexiQ.builder().sqlite("notifications.db").open()) {
            flexiq.registerPeriodic(PeriodicTask.builder("daily-digest", "send_digest", "0 8 * * *")
                    .timezone("America/New_York")
                    .build());

            try (Worker worker = flexiq.worker()
                    .handle(Tasks.SEND_EMAIL, WorkerMain::deliverEmail)
                    .handle(Tasks.SEND_SMS, WorkerMain::deliverSms)
                    .handle(Tasks.SEND_DIGEST, ignored -> buildAndFanOutDigests(flexiq))
                    .queues("default")
                    .start()) {
                worker.awaitShutdown();
            }
        }
    }

    private static Void deliverEmail(Tasks.Email email) {
        // Call your email provider here.
        System.out.println("email -> " + email.to());
        return null;
    }

    private static Void deliverSms(Tasks.Sms sms) {
        // Call your SMS provider here.
        System.out.println("sms -> " + sms.to());
        return null;
    }

    private static Void buildAndFanOutDigests(FlexiQ flexiq) {
        // Build the due digest emails from your data store, then fan out.
        List<Tasks.Email> due = List.of();
        flexiq.enqueueMany(Tasks.SEND_EMAIL, due);
        return null;
    }
}