Loops and retries

Yukta has two different mechanisms for doing something again. Choosing the right one matters.

Need	Use	Scope
A step failed and should be tried again for the same message	Engine retry (`engine.retry`)	One message, one node, with backoff
Repeat an action until a condition becomes true (polling, waiting for readiness)	`LOOP_PREDICATE`	A target plugin, repeated and bounded
Run an action repeatedly and pass every result downstream	`LOOP_STREAM`	A target plugin, each result emitted as a message

Engine retry

A retry reruns a failed attempt with exponential backoff and jitter. It is for transient faults, not for waiting.

{
  "nodeId": "call-api",
  "type": "HTTP_REQUEST",
  "config": {
    "url": "https://service.example.com/orders",
    "method": "POST",
    "engine": {
      "retry": { "maxAttempts": 4, "backoffMs": 200, "maxBackoffMs": 5000 },
      "onError": "ROUTE"
    }
  }
}

A plugin that reports invalid input is never retried. Because a retry can show the same message twice, make downstream side effects idempotent on the message id. See Failure handling.

Poll until a condition holds

LOOP_PREDICATE wraps another plugin, runs it repeatedly and stops when an exit condition is true or a bound is reached. This example polls a command until it has run three times, one second apart, and never runs more than five times or longer than one minute:

{
  "nodeId": "poll",
  "type": "LOOP_PREDICATE",
  "config": {
    "targetPluginId": "PROCESS_EXECUTOR",
    "targetConfig": { "command": ["check-ready"], "failureMode": "CONTINUE" },
    "exitCondition": "#iterationCount >= 3",
    "maxIterations": 5,
    "maxDuration": "PT1M",
    "delayInterval": "PT1S",
    "failureStrategy": "ABORT"
  }
}

Option	Meaning
`targetPluginId`	The plugin type to run on each iteration
`targetConfig`	The target plugin’s own options
`exitCondition`	An expression; the loop ends when it is true. `#iterationCount` is the number of completed iterations
`maxIterations`	Hard cap on iterations
`maxDuration`	Hard cap on total time, as an ISO-8601 duration such as `PT1M`
`delayInterval`	Pause between iterations, as an ISO-8601 duration
`failureStrategy`	What to do if an iteration fails

Always set maxIterations and maxDuration. A loop without a bound that never meets its condition runs until the node’s time limits end it.

Stream every result

LOOP_STREAM runs the target repeatedly and emits each result as its own message, so downstream nodes process results as they arrive. Use it for paging through results or generating a series of items.

Time limits still apply

A loop is one node, so the node’s idle timeout and deadlineMs bound it. Raise timeoutSeconds for long polling, or have the plugin report progress so its idle clock restarts; see Time limits.

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Loops and retries

Engine retry

Poll until a condition holds

Stream every result

Time limits still apply

​Engine retry

​Poll until a condition holds

​Stream every result

​Time limits still apply

​Related

Engine retry

Poll until a condition holds

Stream every result

Time limits still apply

Related