Delay function

Learn more about the delay workflow function within Knock's notification engine.

A delay function does just what it sounds like: it delays the execution of the workflow for some amount of time, then proceeds to the next step. There are three types of delays we support in Knock today: "wait for fixed interval", "wait for a dynamic period", and "wait until a relative timestamp."

Wait for a fixed interval

The "wait for fixed interval" delay type waits for an interval of time (provided by you in the workflow editor) and then proceeds to the next step.

Fixed interval delay functions are helpful for the following use cases:

  • Check to see if a user's seen or read an in-app message before sending an email
  • Remind a user about a pending invite they haven't accepted

Wait for a dynamic period

You can also set the length of your delay dynamically using a variable. You can use any of the data, recipient, actor, or environment variables associated with the workflow run to set your duration.

When specifying a dynamic delay period you must provide one of the following:

  • An ISO-8601 timestamp (e.g. 2022-05-04T20:34:07Z) which must be a datetime in the future
  • A duration unit (e.g { "unit": "seconds", "value": 30 })
  • A window rule (e.g { "frequency": "daily", "hours": 9, "minutes": 30 })

A dynamic delay must be available to be resolved via the key you specify on the given schema, meaning that if you specify a key of delayUntil in your data schema, your workflow trigger data must contain either an ISO-8601 timestamp, a valid duration unit, or a valid window rule.

When the key specified is missing or resolves to an invalid value, a corresponding error will be logged on the workflow run, and the delay will be skipped.

Wait until a relative timestamp

You can use our relative delay to wait some time before or after a timestamp that you provide in your workflow payload. This computes a delay time for a fixed interval relative to a dynamic timestamp.

Relative delay functions are helpful for various scenarios, including:

  • Appointment reminders: send a notification one day before an appointment time
  • Follow-up reminders: send a follow-up message two hours after an event

When configuring a relative delay, you'll specify:

  • A fixed delay interval (provided by you in the workflow editor)
  • Whether the delay should occur before or after the dynamic timestamp
  • The key for the dynamic timestamp (which can come from your trigger data, recipient data, or other sources)

As in the dynamic delay section above, the key specified must be available to be resolved. If the key is missing or resolves to an invalid value, a corresponding error will be logged on the workflow run, and the delay will be skipped.

Using workflow cancellation with delays

In cases where you're waiting to see if a user will complete an action before sending a notification, you can use our workflow cancellation API to ensure a user doesn't receive an unnecessary reminder.

If the user completes the action you were going to remind them about, cancel the workflow to keep any additional notifications from being sent.

Frequently asked questions

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