Domain Identification and Grouping

This skill groups architectural components into logical domains (business areas) to prepare for creating domain services in a service-based architecture.

How to Use

Quick Start

Request analysis of your codebase:

"Group components into logical domains"
"Identify component domains for service-based architecture"
"Create domain groupings from components"
"Analyze which components belong to which domains"

Usage Examples

Example 1: Domain Identification

User: "Group components into logical domains"

The skill will:
1. Analyze component responsibilities and relationships
2. Identify business domains based on functionality
3. Group components into domains
4. Create domain diagrams
5. Suggest namespace refactoring for domain alignment

Example 2: Domain Analysis

User: "Which domain should the billing components belong to?"

The skill will:
1. Analyze billing component functionality
2. Check relationships with other components
3. Identify appropriate domain (e.g., Customer or Financial)
4. Recommend domain assignment

Example 3: Domain Refactoring

User: "What namespace refactoring is needed to align components with domains?"

The skill will:
1. Compare current component namespaces to identified domains
2. Identify misaligned components
3. Suggest namespace changes
4. Create refactoring plan

Step-by-Step Process

Identify Domains: Analyze business capabilities and component relationships
Group Components: Assign components to appropriate domains
Validate Groupings: Ensure components fit well in their domains
Refactor Namespaces: Align component namespaces with domains
Create Domain Map: Visualize domain structure and component groupings

When to Use

Apply this skill when:

After identifying, sizing, and analyzing component dependencies
Before creating domain services (Pattern 6)
When planning service-based architecture migration
Analyzing component relationships and business alignment
Preparing for domain-driven design implementation
Grouping components for better organization

Core Concepts

Domain Definition

A domain is a logical grouping of components that:

Represents a distinct business capability or area
Contains related components that work together
Has clear boundaries and responsibilities
Can become a domain service in service-based architecture

Examples:

Customer Domain: Customer profile, billing, support contracts
Ticketing Domain: Ticket creation, assignment, routing, completion
Reporting Domain: Ticket reports, expert reports, financial reports

Component Domain Relationship

One-to-Many: A single domain contains multiple components

Domain: Customer
├── Component: Customer Profile
├── Component: Billing Payment
├── Component: Billing History
└── Component: Support Contract

Domain Manifestation

Domains are physically manifested through namespace structure:

Before Domain Alignment:

services/billing/payment
services/billing/history
services/customer/profile
services/supportcontract

After Domain Alignment:

services/customer/billing/payment
services/customer/billing/history
services/customer/profile
services/customer/supportcontract

Notice how all customer-related functionality is grouped under .customer domain.

Analysis Process

Phase 1: Identify Business Domains

Analyze the codebase to identify distinct business domains:

Examine Component Responsibilities
- Read component names and descriptions
- Understand what each component does
- Identify business capabilities
Look for Business Language
- Group components by business vocabulary
- Example: "billing", "payment", "invoice" → Financial domain
- Example: "customer", "profile", "contract" → Customer domain
Identify Domain Boundaries
- Where do business concepts change?
- What are the distinct business areas?
- How do components relate to business capabilities?
Collaborate with Business Stakeholders
- Validate domain identification with product owners
- Ensure domains align with business understanding
- Get feedback on domain boundaries

Example Domain Identification:

## Identified Domains

1. **Ticketing Domain** (ss.ticket)
   - Ticket creation, assignment, routing, completion
   - Customer surveys
   - Knowledge base

2. **Customer Domain** (ss.customer)
   - Customer profile
   - Billing and payment
   - Support contracts

3. **Reporting Domain** (ss.reporting)
   - Ticket reports
   - Expert reports
   - Financial reports

4. **Admin Domain** (ss.admin)
   - User maintenance
   - Expert profile management

5. **Shared Domain** (ss.shared)
   - Login
   - Notification

Phase 2: Group Components into Domains

Assign each component to an appropriate domain:

Analyze Component Functionality
- What business capability does it support?
- What domain vocabulary does it use?
- What other components does it relate to?
Check Component Relationships
- Which components are frequently used together?
- What are the dependencies between components?
- Do components share data or workflows?
Assign to Domain
- Place component in domain that best fits its functionality
- Ensure component aligns with domain's business language
- Verify component relationships support domain grouping
Handle Edge Cases
- Components that don't fit clearly: Analyze more deeply
- Components that fit multiple domains: Choose primary domain
- Shared components: May belong to Shared domain

Example Component Grouping:

## Component Domain Assignment

### Ticketing Domain (ss.ticket)

- Ticket Shared (ss.ticket.shared)
- Ticket Maintenance (ss.ticket.maintenance)
- Ticket Completion (ss.ticket.completion)
- Ticket Assign (ss.ticket.assign)
- Ticket Route (ss.ticket.route)
- KB Maintenance (ss.ticket.kb.maintenance)
- KB Search (ss.ticket.kb.search)
- Survey (ss.ticket.survey)

### Customer Domain (ss.customer)

- Customer Profile (ss.customer.profile)
- Billing Payment (ss.customer.billing.payment)
- Billing History (ss.customer.billing.history)
- Support Contract (ss.customer.supportcontract)

### Reporting Domain (ss.reporting)

- Reporting Shared (ss.reporting.shared)
- Ticket Reports (ss.reporting.tickets)
- Expert Reports (ss.reporting.experts)
- Financial Reports (ss.reporting.financial)

Phase 3: Validate Domain Groupings

Ensure components fit well in their assigned domains:

Check Cohesion
- Do components in domain share business language?
- Are components frequently used together?
- Do components have direct relationships?
Verify Boundaries
- Are domain boundaries clear?
- Do components belong to only one domain?
- Are there components that don't fit anywhere?
Assess Completeness
- Are all components assigned to a domain?
- Are domains cohesive and well-formed?
- Do domains represent distinct business capabilities?
Get Stakeholder Validation
- Review domain groupings with product owners
- Ensure domains align with business understanding
- Get feedback on domain boundaries

Validation Checklist:

All components assigned to a domain
Domains have clear boundaries
Components fit well in their domains
Domains represent distinct business capabilities
Stakeholders validate domain groupings

Phase 4: Refactor Namespaces for Domain Alignment

Align component namespaces with identified domains:

Compare Current vs Target Namespaces
- Current: services/billing/payment
- Target: services/customer/billing/payment
- Change: Add .customer domain node
Identify Refactoring Needed
- Which components need namespace changes?
- What domain nodes need to be added?
- Are there components already aligned?
Create Refactoring Plan
- List components needing namespace changes
- Specify target namespace for each
- Prioritize refactoring work
Execute Refactoring
- Update component namespaces
- Update imports/references
- Verify all references updated

Example Namespace Refactoring:

## Namespace Refactoring Plan

### Customer Domain Alignment

| Component        | Current Namespace   | Target Namespace            | Action        |
| ---------------- | ------------------- | --------------------------- | ------------- |
| Billing Payment  | ss.billing.payment  | ss.customer.billing.payment | Add .customer |
| Billing History  | ss.billing.history  | ss.customer.billing.history | Add .customer |
| Customer Profile | ss.customer.profile | ss.customer.profile         | No change     |
| Support Contract | ss.supportcontract  | ss.customer.supportcontract | Add .customer |

### Ticketing Domain Alignment

| Component      | Current Namespace | Target Namespace         | Action      |
| -------------- | ----------------- | ------------------------ | ----------- |
| KB Maintenance | ss.kb.maintenance | ss.ticket.kb.maintenance | Add .ticket |
| KB Search      | ss.kb.search      | ss.ticket.kb.search      | Add .ticket |
| Survey         | ss.survey         | ss.ticket.survey         | Add .ticket |

Phase 5: Create Domain Map

Visualize domain structure and component groupings:

Create Domain Diagram
- Show domains as boxes
- Show components within each domain
- Show relationships between domains
Document Domain Structure
- List domains and their components
- Describe domain responsibilities
- Note domain boundaries
Create Domain Inventory
- Table of domains and components
- Component counts per domain
- Size metrics per domain

Example Domain Map:

## Domain Map

┌─────────────────────────────────────┐ │ Ticketing Domain (ss.ticket) │ ├─────────────────────────────────────┤ │ • Ticket Shared │ │ • Ticket Maintenance │ │ • Ticket Completion │ │ • Ticket Assign │ │ • Ticket Route │ │ • KB Maintenance │ │ • KB Search │ │ • Survey │ └─────────────────────────────────────┘ │ │ uses ▼ ┌─────────────────────────────────────┐ │ Customer Domain (ss.customer) │ ├─────────────────────────────────────┤ │ • Customer Profile │ │ • Billing Payment │ │ • Billing History │ │ • Support Contract │ └─────────────────────────────────────┘


## Output Format

### Domain Identification Report

```markdown
## Domain Identification

### Domain: Customer (ss.customer)

**Business Capability**: Manages customer relationships, billing, and support contracts

**Components**:
- Customer Profile (ss.customer.profile)
- Billing Payment (ss.customer.billing.payment)
- Billing History (ss.customer.billing.history)
- Support Contract (ss.customer.supportcontract)

**Component Count**: 4
**Total Size**: ~15,000 statements (18% of codebase)

**Domain Cohesion**: ✅ High
- Components share customer-related vocabulary
- Components frequently used together
- Direct relationships between components

**Boundaries**:
- Clear separation from Ticketing domain
- Clear separation from Reporting domain
- Shared components (Notification) used by all domains

Component Domain Assignment Table

## Component Domain Assignment

| Component          | Current Namespace     | Assigned Domain | Target Namespace                  |
| ------------------ | --------------------- | --------------- | --------------------------------- |
| Customer Profile   | ss.customer.profile   | Customer        | ss.customer.profile (no change)   |
| Billing Payment    | ss.billing.payment    | Customer        | ss.customer.billing.payment       |
| Ticket Maintenance | ss.ticket.maintenance | Ticketing       | ss.ticket.maintenance (no change) |
| KB Maintenance     | ss.kb.maintenance     | Ticketing       | ss.ticket.kb.maintenance          |
| Reporting Shared   | ss.reporting.shared   | Reporting       | ss.reporting.shared (no change)   |

Namespace Refactoring Plan

## Namespace Refactoring Plan

### Priority: High

**Customer Domain Alignment**

**Components to Refactor**:

1. Billing Payment: `ss.billing.payment` → `ss.customer.billing.payment`
2. Billing History: `ss.billing.history` → `ss.customer.billing.history`
3. Support Contract: `ss.supportcontract` → `ss.customer.supportcontract`

**Steps**:

1. Update namespace declarations in source files
2. Update import statements in dependent components
3. Update directory structure
4. Run tests to verify changes
5. Update documentation

**Expected Impact**:

- All customer-related components aligned under `.customer` domain
- Clearer domain boundaries
- Easier to identify domain components

Domain Map Visualization

## Domain Map

### Domain Structure

Customer Domain (ss.customer) ├── Customer Profile ├── Billing Payment ├── Billing History └── Support Contract

Ticketing Domain (ss.ticket) ├── Ticket Shared ├── Ticket Maintenance ├── Ticket Completion ├── Ticket Assign ├── Ticket Route ├── KB Maintenance ├── KB Search └── Survey

Reporting Domain (ss.reporting) ├── Reporting Shared ├── Ticket Reports ├── Expert Reports └── Financial Reports

Admin Domain (ss.admin) ├── User Maintenance └── Expert Profile

Shared Domain (ss.shared) ├── Login └── Notification


### Domain Relationships

Ticketing Domain │ uses ├─→ Shared Domain (Login, Notification) └─→ Customer Domain (Customer Profile)

Customer Domain │ uses └─→ Shared Domain (Login, Notification)

Reporting Domain │ uses ├─→ Ticketing Domain (Ticket data) ├─→ Customer Domain (Customer data) └─→ Shared Domain (Login)

Analysis Checklist

Domain Identification:

Analyzed component responsibilities
Identified business capabilities
Identified distinct business domains
Validated domains with stakeholders

Component Grouping:

Assigned each component to a domain
Analyzed component relationships
Ensured components fit domain vocabulary
Handled edge cases (shared components, unclear assignments)

Domain Validation:

Checked cohesion within domains
Verified domain boundaries are clear
Ensured all components assigned
Validated with stakeholders

Namespace Refactoring:

Compared current vs target namespaces
Identified components needing refactoring
Created refactoring plan
Prioritized refactoring work

Domain Mapping:

Created domain diagram
Documented domain structure
Created domain inventory table
Documented domain relationships

Implementation Notes

For Node.js/Express Applications

Domains typically organized in services/ directory:

services/
├── customer/              ← Customer Domain
│   ├── profile/
│   ├── billing/
│   │   ├── payment/
│   │   └── history/
│   └── supportcontract/
├── ticket/                ← Ticketing Domain
│   ├── shared/
│   ├── maintenance/
│   ├── assign/
│   └── route/
└── reporting/             ← Reporting Domain
    ├── shared/
    ├── tickets/
    └── experts/

For Java Applications

Domains identified by package structure:

com.company.customer       ← Customer Domain
├── profile
├── billing
│   ├── payment
│   └── history
└── supportcontract

com.company.ticket         ← Ticketing Domain
├── shared
├── maintenance
├── assign
└── route

Domain Identification Strategies

Strategy 1: Business Capability Analysis

Identify what business capabilities the system provides
Group components by capability
Example: "Customer Management" capability → Customer Domain

Strategy 2: Vocabulary Analysis

Identify business vocabulary used by components
Group components sharing same vocabulary
Example: Components using "billing", "payment", "invoice" → Financial Domain

Strategy 3: Relationship Analysis

Identify components frequently used together
Group components with strong relationships
Example: Components that share data/workflows → Same Domain

Strategy 4: Stakeholder Collaboration

Work with product owners/business analysts
Use their understanding of business areas
Validate domain boundaries with them

Fitness Functions

After creating domains, create automated checks:

Domain Namespace Governance

// Ensure components belong to correct domain
function validateDomainNamespaces(components, domainRules) {
  const violations = []

  components.forEach((comp) => {
    const domain = identifyDomain(comp.namespace)
    const expectedDomain = domainRules[comp.name]

    if (domain !== expectedDomain) {
      violations.push({
        component: comp.name,
        currentDomain: domain,
        expectedDomain: expectedDomain,
        namespace: comp.namespace,
      })
    }
  })

  return violations
}

Domain Boundary Enforcement

// Prevent components from accessing other domains directly
function enforceDomainBoundaries(components) {
  const violations = []

  components.forEach((comp) => {
    comp.imports.forEach((imp) => {
      const importedDomain = identifyDomain(imp)
      const componentDomain = identifyDomain(comp.namespace)

      if (importedDomain !== componentDomain && importedDomain !== 'shared') {
        violations.push({
          component: comp.name,
          domain: componentDomain,
          importsFrom: imp,
          importedDomain: importedDomain,
          issue: 'Cross-domain direct dependency',
        })
      }
    })
  })

  return violations
}

Best Practices

Do's ✅

Collaborate with business stakeholders to identify domains
Group components by business capability, not technical layers
Ensure domains represent distinct business areas
Validate domain boundaries with stakeholders
Refactor namespaces to align with domains
Create clear domain documentation
Use business language in domain names

Don'ts ❌

Don't create domains based on technical layers (services, controllers, models)
Don't force components into domains where they don't fit
Don't skip stakeholder validation
Don't create too many small domains (aim for 3-7 domains)
Don't create domains that are too large (monolithic domains)
Don't ignore components that don't fit (analyze why)
Don't skip namespace refactoring (critical for clarity)

Common Domain Patterns

Typical Domains in Business Applications

Customer Domain: Customer management, profiles, relationships
Product Domain: Product catalog, inventory, pricing
Order Domain: Order processing, fulfillment, shipping
Billing Domain: Invoicing, payments, financial transactions
Reporting Domain: Reports, analytics, dashboards
Admin Domain: User management, system configuration
Shared Domain: Common functionality (login, notification, utilities)

Domain Size Guidelines

Small Domain: 2-4 components
Medium Domain: 5-8 components
Large Domain: 9-15 components
Too Large: >15 components (consider splitting)

Next Steps

After creating component domains:

Apply Create Domain Services Pattern - Extract domains to separate services
Plan Service Extraction - Create migration plan for domain services
Implement Domain Services - Move domains to separately deployed services
Monitor Domain Boundaries - Use fitness functions to enforce boundaries

Notes

Domains should represent business capabilities, not technical layers
Domain identification requires collaboration with business stakeholders
Namespace refactoring is critical for domain clarity
Domains prepare the codebase for service-based architecture
Well-formed domains make service extraction easier
Domain boundaries should be clear and well-documented

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