#What is FlowEngine?

FlowEngine is a new front-end no-code, low-code development engine introduced in NocoBase 2.0. It combines models (Model) with flows (Flow) to simplify front-end logic and enhance reusability and maintainability. At the same time, by leveraging the configurable nature of Flow, it provides no-code configuration and orchestration capabilities for front-end components and business logic.

#Why is it called FlowEngine?

Because in FlowEngine, the properties and logic of components are no longer statically defined, but are driven and managed by a Flow.

• Flow, like a data stream, breaks down logic into ordered steps (Step) and applies them to the component sequentially;
• Engine signifies that it is an engine that drives front-end logic and interactions.

Therefore, FlowEngine = A front-end logic engine driven by flows.

#What is a Model?

In FlowEngine, a Model is an abstract model of a component, responsible for:

• Managing the component's properties (Props) and state;
• Defining the component's rendering method;
• Hosting and executing the Flow;
• Uniformly handling event dispatching and lifecycles.

In other words, the Model is the logical brain of the component, turning it from a static element into a configurable and orchestratable dynamic unit.

#What is a Flow?

In FlowEngine, a Flow is a logical flow that serves the Model. Its purpose is to:

• Break down property or event logic into steps (Step) and execute them sequentially in a flow-like manner;
• Manage property changes as well as event responses;
• Make logic dynamic, configurable, and reusable.

#How to understand these concepts?

You can think of a Flow as a stream of water:

• A Step is like a node along the stream's path Each Step performs a small task (e.g., setting a property, triggering an event, calling an API), just as water has an effect when it passes through a gate or a waterwheel.

• The flow is ordered Water flows along a predetermined path from upstream to downstream, passing through all Steps in sequence; similarly, the logic in a Flow is executed in the defined order.

• The flow can be branched and combined A stream of water can be split into multiple smaller streams or merged together; a Flow can also be broken down into multiple sub-flows or combined into more complex logical chains.

• The flow is configurable and controllable The direction and volume of a water stream can be adjusted with a sluice gate; the execution method and parameters of a Flow can also be controlled through configuration (stepParams).

Analogy Summary

• A component is like a waterwheel that needs a stream of water to turn;
• The Model is the base and controller of this waterwheel, responsible for receiving the water and driving its operation;
• The Flow is that stream of water that passes through each Step in order, causing the component to continuously change and respond.

So in FlowEngine:

• Flow allows logic to move naturally like a stream of water;
• Model makes the component the carrier and executor of this stream.