databeginner10 min setupby Mantle

Fan out a list to an API

Receive a list of items by webhook and call an API once per item, five in parallel, continuing past individual failures.

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Purpose

Receive a list of items by webhook and call an API once per item, five in parallel, continuing past individual failures.

How it works

What it does

Webhook batch-in receives {items: [...]}.
For each item iterates the list five at a time (parallel, max_concurrency: 5); a failed item does not stop the others (on_error: continue).
POST item — the loop body — sends each element as the JSON body, with exponential-backoff retry.

Nodes 3

01Batch intrigger.webhookTrigger
02For each itemcontrol.for_eachLogic
03POST itemhttp.requestHTTP

View template JSON

{
  "format": "mantle-workflow/v1",
  "id": "data-fan-out-http",
  "name": "Fan out a list to an API",
  "graph": {
    "nodes": [
      {
        "id": "webhook",
        "type": "trigger.webhook",
        "label": "Batch in",
        "config": {
          "slug": "batch-in",
          "input_schema": {
            "required": [
              "items"
            ],
            "properties": {
              "items": {
                "type": "array"
              }
            }
          }
        },
        "worker_type": "generic-worker",
        "position": {
          "x": 60,
          "y": 220
        }
      },
      {
        "id": "for_each_item",
        "type": "control.for_each",
        "label": "For each item",
        "config": {
          "items": "items",
          "item_as": "item",
          "index_as": "i",
          "parallel": true,
          "max_concurrency": 5,
          "on_error": "continue",
          "empty_collection": "skip",
          "max_items": 1000
        },
        "worker_type": "generic-worker",
        "position": {
          "x": 380,
          "y": 220
        }
      },
      {
        "id": "post_item",
        "type": "http.request",
        "label": "POST item",
        "config": {
          "method": "POST",
          "url": "https://example.com/items",
          "headers": {
            "Content-Type": "application/json"
          },
          "body_from_input": true,
          "timeout_seconds": 15
        },
        "worker_type": "generic-worker",
        "position": {
          "x": 700,
          "y": 220
        },
        "retry": {
          "max_attempts": 3,
          "backoff": "exp",
          "initial_ms": 500,
          "max_ms": 8000
        },
        "parent_id": "for_each_item"
      }
    ],
    "edges": [
      {
        "from": "webhook",
        "to": "for_each_item"
      },
      {
        "from": "for_each_item",
        "to": "post_item"
      }
    ]
  }
}

Requirements

The connections and permissions each step needs, from the node contracts in the catalog.

No connections. This template runs with built-in nodes only.

Setup

Change the destination url on POST item (or use an HTTP connection + path).
Tune max_concurrency and max_items for the downstream API's limits.

Sample input and output

Synthetic examples: node-contract samples or placeholders, never customer data.

Input

The fields the template declares or reads from the request body. Values are placeholders.

{
  "items": []
}

Output

POST item http.request

{
  "body": null,
  "headers": {},
  "status_code": 0
}

Failure handling

What the graph does when a step fails, read from its retry settings, error branches and error policies.

For each item: a failed item is skipped and the other items carry on; the failure stays on its own step.
POST item: up to 3 attempts, exponential backoff from 500 ms up to 8 s.
POST item: the request times out after 15 s.
A step that fails, after any retries, fails the run. The failed step is kept with its input and error.