Resonate Countdown

A Countdown powered by the Resonate Typescript SDK. The countdown sends notifications to ntfy.sh, a simple HTTP-based notification service, at configurable intervals.

The countdown is implemented as a generator function featureing a simple loop that can sleep for hours, days, or weeks powered by Resonate's durability guarantees. At every yield point, Resonate automatically checkpoints the execution and resumes the where where it left off in case of crashes or restarts.

function* countdown(ctx: Context, count: number, delay: number, url: string) {
  for (let i = count; i > 0; i--) {
    // send notification to ntfy.sh
    yield* ctx.run(notify, url, `Countdown: ${i}`);
    // sleep
    yield* ctx.sleep(delay * 60 * 1000);
  }
  // send the last notification to ntfy.sh
  yield* ctx.run(notify, url, `Done`);
}

Try it yourself: Between notifications, kill the worker and restart. The countdown won't be affected—it picks up exactly where it left off.

Setup Dependencies:

1 Setup the Resonate Server

Install the Resonate Server

brew install resonatehq/tap/resonate

2 Setup the countdown

Clone the repository

git clone https://github.com/resonatehq-examples/resonate-countdown-ts.git

Install dependencies

npm install

Running the Project

1. Start the Resonate Server

In Termainl #1, start the Resonate server in development mode listening on http://localhost:8001.

resonate dev

• When you start the server in development mode, the server does not persist data on disk and lose its state when you stop the process

2. Start the Worker

In Termainl #2, start the Resonate worker:

npm start

3. Invoke a Countdown

In Termainl #3, start the countdown, for example, counting down from 5, every minute, and posting notifications to https://ntfy.sh/resonatehq:

resonate invoke countdown.1 --func countdown --arg 5 --arg 1 --arg https://ntfy.sh/resonatehq

Parameters:

• countdown.1: Unique ID for this countdown
• --arg 5: Count down from 5
• --arg 1: Wait 1 minute between counts
• --arg https://ntfy.sh/resonatehq: Where to send notifications

Open https://ntfy.sh/resonatehq in your browser to see the notifications in real-time.

Checking Progress

Get details of a specific countdown:

resonate promises get countdown.1

View all promises:

resonate promises search "*"