Registry Architecture#

FlexiRule uses a Registry Pattern to manage its various components. This architecture allows the system to be highly decoupled and easily extendable by developers.

1. Action Handler Registry#

Every logic node in the Rule Builder (Assignment, Condition, Notify, etc.) has a corresponding Action Handler in the Python backend.

• Handlers are registered at boot time.
• When the engine encounters an action type, it lookups the handler in the registry to execute it.

2. Operator Registry#

Used by the Assignment action to handle different mutation types (Set, Increment, Append, etc.). Developers can register custom operators to support new data transformation logic.

3. Resolver Registry#

Powers the Value Resolver system. It maps a “Kind” (like formula, format, normalization) to a specific resolver class that knows how to compute the result.

Contracts (DTOs)#

Contracts are the “language” spoken between the Python backend and the Vue.js frontend.

The Action Contract#

When the Rule Builder loads, it fetches a Contract DTO for every action type. This DTO includes:

• Capabilities: What the action can do (e.g., is_async, has_condition).
• Config Schema: A JSON Schema that tells the frontend what form fields to render for this action.
• Context Schema: Information about what variables and fields are available for resolution within this action.

Why use Contracts?#

1. Dynamic UI: The frontend doesn’t “know” how to configure a custom Process Operation. It simply follows the schema provided in the contract.
2. Type Safety: Ensures that the data sent from the UI matches what the backend handler expects.
3. Documentation: Contracts serve as a living documentation of the system’s capabilities.

Dynamic UI Generation#

FlexiRule features a Dynamic Control Factory. Instead of hard-coding forms for every action, the UI is built at runtime based on the Action Contract.

• Schema-Driven: We use standard JSON Schema to define configuration parameters.
• Custom Controls: FlexiRule provides specialized Frappe-style controls (Link Pickers, Table Builders, Condition Editors) that can be used within any action configuration form.
• Extensibility: If you create a new Process Operation, you simply define its config_schema in the DocType, and FlexiRule will automatically generate the configuration UI in the Rule Builder.