The paper presents the elements of a novel approach to joint modelling and implementation process of rule-based systems. The design is performed top-down with a three-level, hierarchical approach. It covers conceptual design, logical design and physical design. A new tool, Attribute-Relationship Diagrams (ARD) for logical design stage are put forward. Another logical knowledge representation tool, used at logical design stage consists of the eXtended Tree Tables (XTT). The final, physical design stage consists in mapping to PROLOG meta code. The proposed approach is supported with visual design tool MIRELLA and offers possibility of amalgamating design and implementation into a single procedure. Moreover, incremental verification is also enabled.