# Domain Driven Design

> Domain-Driven Design (DDD)

- Skill: `j4flmao/domain-driven-design` (Agent Skill)
- Install (CLI): `npx skillmds@latest add j4flmao/domain-driven-design`
- Raw SKILL.md: https://api.skillmd.com/api/skills/j4flmao/domain-driven-design/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: j4flmao (https://skillmd.com/u/j4flmao)
- Updated: 2026-09-21
- Page: https://skillmd.com/skills/j4flmao/domain-driven-design

---

# Domain-Driven Design (DDD)

## Core Concepts

DDD is a software engineering approach that centers the design around the business domain, bridging the gap between technical and business teams.

### 1. Ubiquitous Language
A strict, shared vocabulary used by both domain experts (business) and developers. If the business calls it a "Guest", the code should not call it a "User".

### 2. Bounded Contexts
Large systems have overlapping models. A "Product" in the Inventory context means weight and dimensions. A "Product" in the Sales context means price and marketing description. Bounded contexts isolate these models so they don't corrupt each other.

### 3. Aggregates & Roots
An Aggregate is a cluster of domain objects treated as a single unit. The **Aggregate Root** is the only object external entities can reference. (e.g., An `Order` is the root; `OrderLineItem` cannot be accessed directly).

### DDD Architecture Map

```mermaid
%%{init: {"theme": "default", "flowchart": {"useMaxWidth": true}}}%%
flowchart TD
    subgraph ECommerce ["E-Commerce Domain"]
        
        subgraph SalesContext ["Sales Bounded Context"]
            A["Order (Aggregate Root)"]
            B["OrderLineItem (Entity)"]
            A --- B
        end
        
        subgraph InventoryContext ["Inventory Bounded Context"]
            C["Product (Aggregate Root)"]
            D["WarehouseLocation (Value Object)"]
            C --- D
        end
        
    end
    
    subgraph AntiCorruption ["Anti-Corruption Layer (ACL)"]
        E["Event Translator"]
    end
    
    A -.->|"OrderPlacedEvent"| E
    E -.->|"Translate to Inventory terms"| C
```