REPEAT Step

The REPEAT step is used for re-executing a set of steps multiple times. It is ideal for implementing retry logic or polling an external resource until it reaches a desired state.

Properties

Property	Type	Description
type	string	Must be repeat.
count	integer	Maximum number of times to repeat the steps.
repeatOn	string	(Optional) Condition to repeat: SUCCESS or FAILURE.
interval	integer	(Optional) Delay in milliseconds between each repetition.
steps	array	The nested steps to be repeated.

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Behavior

1. The engine executes the child steps.
2. After execution, it checks the repeatOn condition:
   • If repeatOn: FAILURE: It repeats only if the steps failed (returned an error). If they succeeded, the loop breaks.
   • If repeatOn: SUCCESS: It repeats only if the steps succeeded. If they failed, the loop breaks.
   • If repeatOn is omitted: It simply repeats count times regardless of the outcome.
3. If it needs to repeat, it waits for the interval (if any) and then starts again.

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Example: API Retry Logic

Retry a failing API call up to 3 times with a 1-second delay between attempts.

- name: "RetryFetch"
  type: "repeat"
  count: 3
  repeatOn: "FAILURE" # Keep trying as long as it fails
  interval: 1000      # 1 second wait
  steps:
    - type: "invoke"
      service: "api:GetRemoteData"

Example: Simple Polling

Repeat a check 5 times to see if a status has changed.

- name: "PollStatus"
  type: "repeat"
  count: 5
  interval: 2000
  steps:
    - type: "invoke"
      service: "api:CheckStatus"
    # Logic inside could use an EXIT step to break early if 'DONE' is found

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Data Flow Scenario: Successful Retry

Initial Pipeline:

{ "retryCount": 0 }

After 1st Attempt (Failed):

{ "retryCount": 1 }

After 2nd Attempt (Succeeded):

{ "retryCount": 2, "status": "Success" }

(Note: Since the 2nd attempt succeeded and repeatOn is FAILURE, the loop stops)

Tips

• Safety First: Always provide a count to avoid accidental infinite loops.
• Interval: Use interval for external API calls to avoid spamming the remote server and getting rate-limited.
• Error Handling: If the last repetition of a repeatOn: FAILURE block still fails, the entire repeat step will return that final error to the flow.