Mastering Domain‑Driven Design: From Restaurant Analogy to Scalable Architecture

Domain Design

Adopt a pure business perspective to analyze domain problems, aiming for autonomous business domains through a divide‑and‑conquer approach.

Macro Process

Identify major functional areas such as "Dish Domain", "Order Domain", "Kitchen Domain", and "Dining Domain" to locate important regions quickly.

Unified Language

Establish a clear ubiquitous language that captures roles, actions, and entities, e.g., who does what to whom.

Use‑Case Analysis

Focus on relationships between roles and actions without delving into detailed use‑case steps, producing use‑case diagrams.

Domain Partitioning

Refine business areas into sub‑domains based on functional and role relevance, distinguishing true domains from sub‑domains.

Domain Modeling

Model entities, aggregates, and OO relationships, emphasizing aggregation versus composition and defining value objects.

Domain Upstream/Downstream

Describe data‑flow influence relationships, clarifying logical and data impacts across scenarios such as dish management and customer consumption.

Architecture Design

Design architecture to manage complexity, variability, and uncertainty, ensuring that changes in one layer minimally affect others.

Layered Architecture

Structure the system into Interface Layer, Domain Use‑Case Layer, Domain Model Layer, Dependency Layer, and Infrastructure Layer, each with distinct responsibilities.

Architecture Mapping

Map business domains to architectural elements, maintaining consistent viewpoints (e.g., restaurant → system, kitchen → application → module).

Key Constraints

Lower layers must remain stable and not depend on upper layers.

Use rich domain models that follow OOP principles without over‑loading entities with unrelated capabilities.

Interface and dependency layers are technology‑focused and must stay free of business logic.

Domain layers must be environment‑independent and minimally dependent on external resources.

Microservice Decomposition

Derive microservices from domain boundaries, resulting in services such as Kitchen, Dish, and Order, while keeping tightly coupled sub‑domains together.

Functional Design (Use‑Case Implementation)

Translate design into concrete functionality, ensuring extensibility and stability.

Concept of Function

Recognize that functions evolve; abstract them to higher‑level concepts like "cooking" rather than specific dishes.

Event Storming

Decompose complex functions into events, identify participating roles, domains, and steps, and produce event‑storming models.

Use‑Case Analysis and Diagrams

Analyze commonalities and differences, create use‑case diagrams, class structure diagrams, flowcharts, and activity/sequence diagrams to map events to code.

Coding Implementation

Emphasize that the ultimate goal is to solve software complexity by guiding developers with clear design artifacts.