Before installing Drools, it’s important to understand the main components in the ecosystem and how they work together.
Drools (BRM / Rule Engine)
Drools is the core rules engine. It executes your business rules written in:
- DRL (Drools Rule Language)
- Guided Rules (via a UI editor)
- Decision Tables (spreadsheet-like rules)
- DMN Models (Decision Model & Notation standard)
Think of Drools as the engine under the hood that does the actual reasoning and decision-making.
Business Central
Business Central is the web-based workbench for designing and managing business rules. It allows you to:
- Author rules in multiple formats (DRL, decision tables, guided rules, DMN).
- Test and validate rules.
- Manage projects and versioning.
- Deploy projects to KIE Server.
👉 Analogy: Business Central is like the IDE (development environment) for Drools, but in a browser.
KIE Server
KIE Server is the runtime execution server. Its role is to:
- Host the deployed rules, processes, and decision models.
- Provide REST and JMS APIs so applications can invoke rules.
- Scale out execution separate from rule authoring.
👉 Analogy: KIE Server is the production runtime that runs the rules created in Business Central.
Relationship Between Components
- Business Central is where rules are authored, tested, and packaged.
- KIE Server is where rules are executed at runtime.
- Drools is the engine inside KIE Server that evaluates rules.
- Communication: Business Central manages and controls KIE Server deployments via REST APIs. This link is configured using the
KIE_SERVER_CONTROLLERenvironment variable in Docker.
✅ In short:
- Drools = engine.
- Business Central = development & management UI.
- KIE Server = runtime execution environment.