Webinar countdown API

Fixed timer

// A single webinar: one fixed timer.
const timer = await call("/timers", {
  method: "POST",
  headers: { "Idempotency-Key": `webinar_${webinar.id}` },
  body: JSON.stringify({
    name: webinar.title,
    type: "fixed",
    deadline_at: webinar.startsAt,      // ISO 8601 with an offset
    timezone: "Europe/London",          // the zone it was scheduled in
    publish: true,
    expiry: {
      behavior: "redirect",
      redirect_url: webinar.roomUrl,    // send latecomers straight in
    },
    metadata: { webinar_id: webinar.id },
  }),
});

Recurring timer

// A weekly demo that runs every Thursday at 14:00 Berlin time.
// One timer, forever — not 52 timers a year.
const timer = await call("/timers", {
  method: "POST",
  headers: { "Idempotency-Key": "weekly_product_demo" },
  body: JSON.stringify({
    name: "Weekly product demo",
    type: "recurring",
    recurrence: {
      frequency: "weekly",
      days_of_week: ["thursday"],
      local_time: "14:00",
    },
    // Occurrences are computed in this zone, so 14:00 stays 14:00
    // through a daylight saving change instead of drifting.
    timezone: "Europe/Berlin",
    publish: true,
  }),
});

Four rules on one timer

// Reminders, then the room. Note the delivery setting.
const MILESTONES = [
  { name: "24 hours before", seconds: 86400 },
  { name: "1 hour before", seconds: 3600 },
  { name: "10 minutes before", seconds: 600 },
];

for (const milestone of MILESTONES) {
  await call(`/timers/${timer.id}/webhook-rules`, {
    method: "POST",
    body: JSON.stringify({
      name: milestone.name,
      webhook_destination_id: DESTINATION_ID,
      condition: {
        field: "remaining_seconds",
        operator: "less_than_or_equal",
        value: milestone.seconds,
      },
      // "repeat" for a recurring webinar, "once" for a one-off.
      // A "once" rule on a recurring timer fires on the first
      // cycle and then never again.
      delivery: webinar.recurring ? "repeat" : "once",
    }),
  });
}

await call(`/timers/${timer.id}/webhook-rules`, {
  method: "POST",
  body: JSON.stringify({
    name: "Doors open",
    webhook_destination_id: DESTINATION_ID,
    condition: { field: "status", operator: "equals", value: "ended" },
    delivery: webinar.recurring ? "repeat" : "once",
  }),
});

One endpoint, four branches

async function handleWebinarEvent(event) {
  const webinarId = event.timer.metadata.webinar_id;
  const registrants = await db.registrants.forWebinar(webinarId);

  switch (event.rule.name) {
    case "24 hours before":
      return sendReminder(registrants, "tomorrow");

    case "1 hour before":
      return sendReminder(registrants, "in an hour");

    case "10 minutes before":
      // The one that actually moves attendance.
      return sendPushAndSms(registrants);

    case "Doors open":
      await db.webinars.update(webinarId, { roomOpen: true });
      return sendJoinLink(registrants);
  }
}

Reminder email

// Every reminder carries a live countdown, so an email opened
// three hours after it was sent shows three hours less.
const outputs = await call(`/timers/${webinar.timerId}/outputs`);

await sendEmail({
  to: registrant.email,
  subject: `${webinar.title} starts soon`,
  html: `
    <p>Hi ${registrant.firstName},</p>
    <p>Starting in:</p>
    ${outputs.email_embed_html}
    <p><a href="${webinar.roomUrl}">Join the room</a></p>
  `,
});