# Sub Flow

Use the **Sub Flow** node to invoke another **Microflow** from within a main Microflow.\
Sub Flow enables developers to **break complex integration logic into smaller, reusable flows**, simplifying both design and maintenance.

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### Purpose

The **Sub Flow** node is used to:

* Call another Microflow from a parent Microflow
* Encapsulate a **stand‑alone section of logic** into a separate flow
* Improve readability of the main integration flow
* Promote **reusability and modular design**

If a portion of the main flow performs a specific, reusable task (for example, validation, transformation, or external lookup), it is a recommended practice to implement that logic as a separate Microflow and invoke it using a Sub Flow node.

***

### Benefits of Using Sub Flow

Using Sub Flow helps to:

* Avoid duplication of logic across multiple flows
* Apply the **single responsibility principle**
* Maintain smaller, easier‑to‑understand Microflows
* Simplify testing and troubleshooting
* Enable reuse of integration logic across multiple scenarios

Sub Flow is a key enabler for **clean and scalable integration design**.

***

### Sub Flow Node Configuration

The **Sub Flow Node Configuration Panel** contains **three tabs**, each responsible for a different aspect of configuration.

***

#### General Tab

The **General** tab contains basic node information, including:

* Title
* Task ID (system‑generated)
* Description

These properties help document and identify the Sub Flow within the parent Microflow.

***

#### Business Object Tab

The **Business Object** tab is used to configure:

* Input Business Objects passed to the Sub Flow
* Output Business Objects returned from the Sub Flow

This ensures a clear and well‑defined data contract between the parent flow and the sub flow.

***

#### Sub Flow Tab

The **Sub Flow** tab is used to select and manage the referenced Microflow.

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| Property  | Mandatory | Description                                      |
| --------- | --------- | ------------------------------------------------ |
| Flow Name | Yes       | Select the Microflow to be invoked as a Sub Flow |

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### Sub Flow Actions

Within the **Sub Flow** tab, the following actions are available:

* **Open Sub Flow**\
  Opens the selected sub Microflow for viewing or editing.
* **Open Mapping Parameter**\
  Opens the **Mapping Parameter screen**, where users can:
  * Map input parameters from the parent Microflow to the Sub Flow
  * Map output parameters from the Sub Flow back to the parent Microflow

This mapping mechanism ensures seamless data transfer between flows.

***

### Best Practices for Using Sub Flow

* Use Sub Flow for logic that is reused in multiple Microflows
* Keep sub flows focused on a single responsibility
* Clearly define input and output Business Objects
* Avoid deeply nested sub flows to maintain flow readability
* Use meaningful names for sub flows to reflect their purpose

***

### Summary

The **Sub Flow** node is a powerful mechanism for **modularizing integration logic** in ONEWEB Microflows.

By using Sub Flow, developers can:

* Structure large integration flows into manageable components
* Reuse common logic consistently
* Improve clarity, maintainability, and scalability
* Enforce clean architectural boundaries

Sub Flow plays a crucial role in building **robust, maintainable, and enterprise‑grade integrations** using ONEWEB.


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