domain-analysis

Subdomain Identification & Bounded Context Analysis

This skill analyzes codebases to identify subdomains (Core, Supporting, Generic) and suggest bounded contexts following Domain-Driven Design Strategic Design principles.

When to Use

Apply this skill when:

Analyzing domain boundaries in any codebase

Identifying Core, Supporting, and Generic subdomains

Mapping bounded contexts from problem space to solution space

Assessing domain cohesion and detecting coupling issues

Planning domain-driven refactoring

Understanding business capabilities in code

Core Principles

Subdomain Classification

Core Domain

Competitive advantage, highest business value, requires best developers

Indicators: Complex business logic, frequent changes, domain experts needed

Supporting Subdomain

Essential but not differentiating, business-specific

Indicators: Supports Core Domain, moderate complexity, business-specific rules

Generic Subdomain

Common functionality, could be outsourced Indicators: Well-understood problem, low differentiation, standard functionality Bounded Context An explicit linguistic boundary where domain terms have specific, unambiguous meanings. Primary nature: Linguistic boundary, not technical Key rule: Inside boundary, all Ubiquitous Language terms are unambiguous Goal: Align 1 subdomain to 1 bounded context (ideal) Analysis Process Phase 1: Extract Concepts Scan codebase for business concepts (not infrastructure): Entities (domain models with identity) Patterns: @Entity , class , domain models Focus: Business concepts, not technical classes Services (business operations) Patterns: Service , Manager , Handler Focus: Business logic, not technical utilities Use Cases (business workflows) Patterns: UseCase , Command , Handler Focus: Business processes, not CRUD Controllers/Resolvers (entry points) Patterns: Controller , Resolver , API endpoints Focus: Business capabilities, not technical routes Phase 2: Group by Ubiquitous Language For each concept, determine: Primary Language Context What business vocabulary does this belong to? Examples: Subscription , Invoice , Payment → Billing language Movie , Video , Episode → Content language User , Authentication → Identity language Linguistic Boundaries Where do term meanings change? Same term, different meaning = different bounded context Example: "Customer" in Sales vs "Customer" in Support Concept Relationships Which concepts naturally belong together? Which share business vocabulary? Which reference each other? Phase 3: Identify Subdomains A subdomain has: Distinct business capability Independent business value Unique vocabulary Multiple related entities working together Cohesive set of business operations Common Domain Patterns : Billing/Subscription: Payments, invoices, plans Content/Catalog: Media, products, inventory Identity/Access: Users, authentication, authorization Analytics: Metrics, dashboards, insights Notifications: Messages, alerts, communications Classify Each Subdomain : Use this decision tree: Is it a competitive advantage? YES → Core Domain NO → Does it require business-specific knowledge? YES → Supporting Subdomain NO → Generic Subdomain Phase 4: Assess Cohesion High Cohesion Indicators ✅ Concepts share Ubiquitous Language Concepts frequently used together Direct business relationships Changes to one affect others in group Solve same business problem Low Cohesion Indicators ❌ Different business vocabularies mixed Concepts rarely used together No direct business relationship Changes don't affect others Solve different business problems Cohesion Score Formula : Score = ( Linguistic Cohesion (0-3) + // Shared vocabulary Usage Cohesion (0-3) + // Used together Data Cohesion (0-2) + // Entity relationships Change Cohesion (0-2) // Change together ) / 10 8-10: High Cohesion ✅ 5-7: Medium Cohesion ⚠️ 0-4: Low Cohesion ❌ Phase 5: Detect Low Cohesion Issues Rule 1: Linguistic Mismatch Problem: Different business vocabularies mixed Example: User (identity) + Subscription (billing) in same service Action: Suggest separation into different bounded contexts Rule 2: Cross-Domain Dependencies Problem: Tight coupling between domains Example: Service A directly instantiates entities from Domain B Action: Suggest interface-based integration Rule 3: Mixed Responsibilities Problem: Single class handles multiple business concerns Example: Service handling both billing and content Action: Suggest splitting by subdomain Rule 4: Generic in Core Problem: Generic functionality in core business logic Example: Email sending in billing service Action: Extract to Generic Subdomain Rule 5: Unclear Boundaries Problem: Cannot determine which domain concept belongs to Example: Entity with relationships to multiple domains Action: Clarify boundaries, possibly split concept Phase 6: Map Bounded Contexts For each subdomain identified, suggest bounded context: Bounded Context Characteristics : Name reflects Ubiquitous Language Contains complete domain model Has explicit integration points Clear linguistic boundary Integration Patterns : Shared Kernel: Shared model between contexts (use sparingly) Customer/Supplier: Downstream depends on upstream Conformist: Downstream conforms to upstream Anti-corruption Layer: Translation layer between contexts Open Host Service: Published interface for integration Published Language: Well-documented integration protocol Output Format Domain Map For each domain/subdomain:

Domain:

**

Type

**

Core Domain | Supporting Subdomain | Generic Subdomain

**

Ubiquitous Language

**

{key business terms}

**

Business Capability

**

{what business problem it solves}

**

Key Concepts

**

:

-

{Concept} (Entity|Service|UseCase) -

**

Subdomains

**

(if applicable):

1.

{Subdomain} (Core|Supporting|Generic)

-

Concepts:

-

Cohesion: {score}/10

-

Dependencies: →

**

Suggested Bounded Context

**

{Name}Context

Linguistic boundary:

Integration:

**

Dependencies

**

:

-

→ {OtherDomain} via {interface/API}

-

← {OtherDomain} via {interface/API}

**

Cohesion Score

**

{score}/10 Cohesion Matrix

Cross-Domain Cohesion | Domain A | Domain B | Cohesion | Issue | Recommendation | |

|

|

|

|

| | Billing | Identity | 2/10 | ❌ Direct coupling | Use interface | | Content | Billing | 6/10 | ⚠️ Usage tracking | Event-based integration | Low Cohesion Report

Issues Detected

Priority: High

**

Issue

**

{description}

**

Location

**

{file/class/method}

**

Problem

**

{what's wrong}

**

Concepts

**

{involved concepts}

**

Cohesion

**

{score}/10

**

Recommendation

**

{suggested fix}

Priority: Medium {similar format} Bounded Context Map

Suggested Bounded Contexts

{ContextName}Context ** Contains Subdomains ** : - {Subdomain1} (Core) - {Subdomain2} (Supporting) ** Ubiquitous Language ** : - Term: Definition in this context ** Integration Requirements ** : - Consumes from: {OtherContext} via {pattern} - Publishes to: {OtherContext} via {pattern} ** Implementation Notes ** : - Separate persistence - Independent deployment - Explicit API boundaries Best Practices Do's ✅ Focus on business language, not code structure Let Ubiquitous Language guide boundaries Measure cohesion objectively Identify clear integration points Classify every subdomain (Core/Supporting/Generic) Look for linguistic boundaries first Don'ts ❌ Don't group by technical layers Don't force single global model Don't ignore linguistic differences Don't couple domains directly Don't create contexts by architecture Don't eliminate all dependencies (some are necessary) Analysis Checklist For Each Concept : What business language does it belong to? What domain/subdomain is it part of? Is it Core, Supporting, or Generic? What other concepts does it relate to? Are dependencies within same domain? Any linguistic mismatches? For Each Domain : What is the Ubiquitous Language? What are the key concepts? What are the subdomains? Which is the Core Domain? What are cross-domain dependencies? Is internal cohesion high? Are boundaries clear? For Cohesion Analysis : Calculate cohesion scores Identify low cohesion areas Map cross-domain dependencies Flag linguistic mismatches Note tight coupling Suggest boundary clarifications Quick Reference Subdomain Decision Tree Analyze business capability └─ Is it competitive advantage? ├─ YES → Core Domain └─ NO → Is it business-specific? ├─ YES → Supporting Subdomain └─ NO → Generic Subdomain Cohesion Quick Check Same vocabulary? → High linguistic cohesion Used together? → High usage cohesion Direct relationships? → High data cohesion Change together? → High change cohesion All high → Strong subdomain candidate Mix of high/low → Review boundaries All low → Likely wrong grouping Bounded Context Signals Clear boundary signs: ✅ Distinct Ubiquitous Language ✅ Concepts have unambiguous meaning ✅ Different meanings across contexts ✅ Clear integration points Unclear boundary signs: ❌ Same terms with same meanings everywhere ❌ Concepts used identically across system ❌ No clear linguistic differences ❌ Tight coupling everywhere Anti-Patterns to Avoid Big Ball of Mud Everything connected to everything No clear boundaries Mixed vocabularies Prevention: Explicit bounded contexts All-Inclusive Model Single model for entire business Impossible global definitions Creates conflicts Prevention: Embrace multiple contexts Mixed Linguistic Concepts Different vocabularies in same context Example: User/Permission with Forum/Post Prevention: Keep linguistic associations Notes This is strategic analysis, not tactical implementation Focus on WHAT domains exist, not HOW to implement Some cross-domain dependencies are normal Low cohesion doesn't always mean "bad," it means "needs attention" Generic Subdomains naturally have lower cohesion Always validate with domain experts when possible Validation Criteria Good domain identification has: ✅ Clear boundaries with distinct Ubiquitous Language ✅ High internal cohesion within domains ✅ Explicit cross-domain dependencies ✅ Business alignment with capabilities ✅ Actionable recommendations for issues