# Custom Logic / Coding

Although ONEWEB provides a rich set of built‑in integration nodes, certain integration scenarios may require **custom logic** that goes beyond the default capabilities.\
To support such cases, **Microflow** provides a **Java Node**, allowing developers to execute **custom Java code** as part of an integration flow.

This approach ensures that advanced or highly specific logic can still be implemented, while keeping the overall integration model consistent and reusable.

***

### Purpose of Custom Logic in Microflow

Custom logic is typically used when:

* Specialized computation is required
* Proprietary algorithms must be implemented
* Third‑party Java libraries need to be leveraged
* Integration logic cannot be expressed using standard nodes

By encapsulating custom logic inside Java classes, Microflows can remain **clean, orchestrative, and low‑code**, while complex logic is handled externally.

***

### Java Node in Microflow

The **Java Node** allows a Microflow to invoke a Java method packaged as a **JAR file**.

Using the Java Node, developers can:

* Execute custom Java logic during Microflow execution
* Pass data from Microflow to Java methods
* Receive computed results back into the Microflow
* Combine low‑code integration with full‑code extensibility

The Java Node acts as a **bridge between low‑code and full‑code development**.

***

### How to Add Custom Logic Using Java Node

To add custom logic to a Microflow, follow these steps:

1. **Create a Java Class**
   * Implement the required custom logic in Java
   * Define clear input parameters and return values
2. **Export the Java Code as a JAR File**
   * Compile and package the Java class into a JAR
3. **Upload the JAR File**
   * Upload the JAR file using the Microflow Java Node interface
4. **Add Java Node to Microflow**
   * Drag and drop the **Java Node activity** onto the Microflow diagram
5. **Configure the Java Node**
   * Select the **JAR Name** (choose from uploaded JARs)
   * Click **Get Class Name** and select the Java class
   * Select the method to execute in **Method Name**
6. **Map Parameters**
   * Open **Mapping Parameters**
   * Map Microflow input parameters to Java method arguments
   * Map Java method return values back to Microflow parameters
7. **Save Configuration**
   * Click **Done** to save the Java Node settings

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***

### Managing Dependent JAR Files

When custom Java logic depends on external libraries:

* **Do not bundle dependencies into the main Java Node JAR**
* Upload dependency JARs separately using the **Upload JAR utility**
* Allow administrators to manage and version shared libraries centrally

This practice:

* Avoids classpath conflicts
* Improves dependency governance
* Makes shared utilities easier to maintain

***

### Best Practices for Custom Logic

* Keep Java logic focused and reusable
* Follow the **single responsibility principle**
* Clearly define input/output contracts
* Prefer Microflow nodes over Java when possible
* Use Java Node only when necessary

This ensures that Microflows remain readable, maintainable, and aligned with low‑code design principles.

***

### Summary

**Custom Logic / Coding** in ONEWEB enables developers to extend Microflows with full‑fledged Java functionality when required.

By using the **Java Node**, applications can:

* Execute complex or proprietary logic
* Integrate with external Java libraries
* Maintain a clean separation between orchestration and computation
* Combine low‑code integration with full‑code flexibility

This hybrid approach ensures that ONEWEB remains both **developer‑friendly and enterprise‑capable**, even in advanced integration scenarios.


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