resonate-durable-sleep-scheduled-work-java

Resonate Durable Sleep + Scheduled Work — Java

Prerelease note. resonate-sdk-java is published on Maven Central — pin io.resonatehq:resonate-sdk-java:0.1.1. The API mirrors the Python SDK and may change before a stable 1.0. Requires Java 21+ (virtual threads, a feature generally available in Java 21). Every code block here is compile-verified against 0.1.1 and drawn from example-countdown-java / example-quickstart-java and develop/java.mdx (docs PR #230).

Overview

Two related capabilities in the Java SDK:

1. Durable sleep inside a workflow — ctx.sleep(Duration) pauses execution; the worker process can exit and resume later without losing its place. The server holds the timer promise; the cost is one promise record, not process uptime.
2. Scheduled / recurring work — r.schedule(...) registers a cron schedule that periodically invokes a registered function. The Java SDK includes this top-level Schedule API (plus the lower-level r.schedules sub-client); Go's 0.1.0 tag has the lower-level Schedules() sub-client (direct cron-fired promises) but not this same one-call function-dispatch convenience yet. This removes the need for an in-workflow sleep loop or an external cron trigger.

Both patterns are durable: Resonate holds the continuation (or the schedule) in its store, not in a long-running thread.

When to use

• Delays spanning minutes, hours, days, or weeks that must survive crashes (ctx.sleep)
• Reminder sequences (7-day trial expiry, multi-stage onboarding drips)
• Countdown workflows that act on each tick
• Periodic jobs on a fixed cron (r.schedule) — daily reports, nightly reconciliation
• Anywhere you would reach for Thread.sleep but need the work to survive a process restart

ctx.sleep basics

ctx.sleep takes a java.time.Duration and returns a future with no value to decode — await() to suspend until the timer fires.

import io.resonatehq.resonate.Context;
import java.time.Duration;

public static void reminder(Context ctx) {
    ctx.sleep(Duration.ofHours(1)).await(); // no value to decode; suspends until the timer fires
    // ... send the reminder
}