Article Type: Node Reference
Audience: Developers, App Admins
Module: Data Flows / Node Designer
Applies to Versions: Platform 3.0+
Prerequisites: Basic understanding of Data Flow concepts

1. Overview

What are Source & Trigger Nodes?

Fuuz is an event-driven platform, and Source & Trigger nodes are crucial for building reactive solutions. These nodes provide flexibility to listen on event streams within the platform or events triggered by external systems. Source nodes are the starting points that determine when and how a flow executes, providing the initial payload.

Categories of Nodes:

• Debug/Testing Nodes: Used during development to simulate triggers and test flows
• Production Event Nodes: Deployed triggers that listen for real events in production
• Pub/Sub Nodes: Topic-based messaging for decoupled, asynchronous communication

Complete Node Reference

2. Source Node (Debug)

The Source node allows you to use a payload from anywhere that you can paste directly into the node's editor panel and then consume in your flow for testing purposes. In a production scenario, the contents of this node's payload would be replaced by some other listener, trigger, or API call.

Configuration Parameters

3. File Source Node (Debug)

The File Source node provides the option to attach a file from your local system to simulate receiving data from a third party. This is useful when testing flows that would normally be called through a Request/Response or would pull a file from an FTP you don't currently have access to.

Configuration Parameters

File Encoding Guide

4. Data Change Source Node (Debug)

Fuuz is an event-driven architecture that allows you to listen on event streams for many different types. Data change events are emitted when a record in a data model is created, updated, or deleted.

The Data Change Source node allows you to simulate this data being sent into the flow, as the data change event stream is not started until you have deployed the flow.

Configuration Parameters

5. Data Changes Node (Production)

The Data Changes node allows you to listen on data change event streams from the Fuuz Platform for System models or custom Application models. When a record is created, updated, or deleted, the platform creates an event with the type of model, the operation, and the data before and after the change.

Configuration Parameters

6. Request and Response Node

The Request node is used to initiate a flow in Fuuz from an internal or external request. You must use a Response node on all terminating branches of the Data Flow to respond to the request with the payload.

This node is very useful for creating modular processes that perform specific actions and can be called by other flows using the Execute Flow node.

Usage Requirements

• Request Node: Entry point for the flow - receives incoming payload
• Response Node: Must be placed on all terminating branches to return data
• Flows with Request nodes can be called via Execute Flow node or external HTTP requests

7. Device Subscription Node

The Device Subscription node is used to subscribe to devices setup in Fuuz through the gateway. Any dropdowns left blank will act as a wildcard, allowing you to subscribe to multiple subscriptions with one node.

Configuration Parameters

8. Webhook Node

The Webhook node is used to receive requests to a webhook made inside or outside of the platform. Webhooks are defined from the "System" screen under "Webhooks". Webhooks are topics that can be published to through an HTTP POST request from outside of the system.

Configuration Parameters

9. Topic Node (Subscribe)

The Topic node is used to subscribe to messages from a specific topic. Topics are user-created event streams. To receive an event on a topic, another process (Screen or Data Flow) must publish to it first. The data published must be valid JSON.

Configuration Parameters

10. Publish Node

The Publish node allows you to publish data to a topic created in the platform. This is useful for chaining multiple processes together.

Use Case Example

You have two Data Flows: A and B. Flow B is dependent on the completion of Flow A, but Flow A may take a long time to complete. You can publish an event when Flow A completes. Flow B listens on the topic Flow A publishes to. Once Flow B receives an event on that topic, it can start its process.

Configuration Parameters

11. Payload Wrapping Behavior

Both Topic and Webhook nodes wrap incoming payloads in a "value" property. This is important to understand when designing flows.

Example

Published Payload:

{
  "data": {
    "Part_No": "123",
    "Revision": "A"
  }
}

Topic/Webhook Node Output:

{
  "value": {
    "data": {
      "Part_No": "123",
      "Revision": "A"
    }
  }
}

Handling the Wrapper

The easiest way to handle this is with a script node after the Topic/Webhook node that removes the value property wrapping your payload:

$.value

12. Best Practices

Event Design Standards

• All flows with a Request node must have at least one Response Node on every branch
• Data Changes should be followed immediately by a conditional to reduce unnecessary executions
• Topics, publishing, and subscribing are preferred for handling pagination of large data sets
• Handle the "value" wrapper from Topic/Webhook nodes with a script node
• Remove Source nodes before deploying to production

Topic/Publish Patterns

• Use topics to decouple long-running processes
• Use Bulk Publishing for processing arrays as individual events
• Disable Bulk Publishing when you need the entire array as one payload
• Consider using topics for retry patterns and error handling

Debug/Testing Patterns

• Use Data Change Source to test flows before deployment (event stream doesn't start until deployed)
• Use File Source with proper encoding (UTF8 for text, Base64 for binary)
• Source node Context changes do NOT persist - use Set/Merge Context nodes for production

13. Troubleshooting

14. Related Resources

• Data Flow Design Standards - Event handling guidelines
• Fuuz Platform Nodes Complete Guide - Execute Flow for calling Request/Response flows
• IIoT/Gateway Nodes Complete Guide - Device setup and gateway configuration
• Flow Control Nodes Complete Guide - Schedule Node for time-based triggers
• Debugging & Context Nodes Complete Guide - Additional debug tools
• Notification Nodes Complete Guide - Send/Receive notifications
• System Administration - Webhook configuration
• Platform Website: fuuz.com

15. Revision History