Triggers and Schedules

A workflow sitting idle does nothing useful. For all the power of a multi-agent pipeline, it has no effect until something tells it to start. The mechanism that starts a workflow is called a trigger. Triggers are the on-switches of automation — and understanding them is essential to designing systems that respond to the right events at the right moments.

Two Kinds of Triggers

All triggers fall into one of two broad categories: event-based triggers and schedule-based triggers. An event-based trigger fires when something specific happens — a new email arrives, a file is uploaded, a sensor reading crosses a threshold, a user submits a form, or a payment is received. The workflow is dormant until the event occurs, then springs into action. Event triggers are reactive: they respond to the world changing. A schedule-based trigger fires at a specific time or on a repeating interval — every morning at 6 a.m., every Monday, the first day of each month, every fifteen minutes. The workflow does not wait for anything to happen; it runs because the clock says it is time. Schedule triggers are proactive: they run whether anything changed or not.

Many real systems combine both types. A hospital system might run a scheduled workflow every night to analyze all of the day's patient data. It might also have an event-triggered workflow that fires the instant a patient's heart monitor reading goes outside a safe range. The nightly schedule catches trends over time; the event trigger catches emergencies in real time.

Event-Based Triggers in Detail

Event triggers rely on a system watching for a specific signal and responding when it appears. The signal is usually produced by another system or by user action, and is communicated via a message or a webhook — a kind of automated notification sent from one software system to another. When a customer completes a purchase on an e-commerce site, an event fires. That event might trigger several workflows at once: one sends a confirmation email, another updates the inventory database, a third schedules a shipping label, and a fourth logs the sale in an analytics report. Multiple workflows can be triggered by a single event — they run in parallel, each handling its own piece of the response.

Schedule-Based Triggers: Cron and Intervals

Schedule-based triggers use a timing system — most commonly a format called cron — to specify exactly when a workflow should run. Cron syntax looks cryptic at first ('0 6 * * 1' means 'every Monday at 6:00 a.m.') but it gives developers precise control over when automations fire. Simpler scheduling systems let you describe intervals in plain language: 'every hour,' 'every weekday at noon,' 'the last Sunday of each month.' Under the hood, these are still parsed into a timing format the system can execute. Schedule triggers are ideal for tasks that need to happen on a predictable rhythm, regardless of user action: backups, reports, data syncs, and maintenance tasks are all classic examples.