Module-Based Architecture

Module-based architecture aligns technical system boundaries with business domain boundaries, creating more maintainable, scalable, and understandable systems. This approach is particularly effective when combined with GenAI integration, as it provides clear contexts for AI features and development acceleration.

Core Concepts

Business Modules as System Modules

Each business capability becomes a distinct system module with clear responsibilities:

Module Characteristics

Each module exhibits these properties:

• Domain Cohesion: All functionality relates to a single business domain
• Interface Independence: Interacts with other modules only through defined APIs
• Data Ownership: Manages its own data and business rules
• Deployment Independence: Can be developed, tested, and deployed separately

Architecture Patterns

Modular Monolith Pattern

Start with a modular monolith for simplicity while maintaining clear boundaries:

Module Communication Patterns

Direct API Calls (Synchronous)

Event-Driven Communication (Asynchronous)

Implementation Strategy

Phase 1: Module Identification

Identify business capabilities and their boundaries:

Business Capability Mapping

Business Capability	Core Responsibilities	Dependencies
User Management	Authentication, profiles, permissions	None
Content Management	Creation, storage, delivery, search	User Management
Payment Processing	Billing, subscriptions, invoices	User Management
Analytics & Reporting	Usage tracking, business intelligence	User Management, Content
Notification System	Email, SMS, push notifications	User Management

Phase 2: Module Interface Design

API Design Principles

• RESTful APIs: Standard HTTP methods and status codes
• Versioning Strategy: Backward compatibility for interface evolution
• Input Validation: Consistent error handling and response formats
• Documentation: OpenAPI specifications for all module interfaces

Sample Module API

# User Module API Specification
openapi: 3.0.0
info:
  title: User Module API
  version: 1.0.0

paths:
  /users:
    get:
      summary: List users
      parameters:
        - name: limit
          in: query
          schema:
            type: integer
            minimum: 1
            maximum: 100
        - name: offset
          in: query
          schema:
            type: integer
            minimum: 0
      responses:
        '200':
          description: List of users
          content:
            application/json:
              schema:
                type: object
                properties:
                  users:
                    type: array
                    items:
                      $ref: '#/components/schemas/User'
                  total:
                    type: integer
                  
    post:
      summary: Create new user
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/CreateUserRequest'
      responses:
        '201':
          description: User created successfully
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/User'

components:
  schemas:
    User:
      type: object
      properties:
        id:
          type: string
          format: uuid
        email:
          type: string
          format: email
        name:
          type: string
        created_at:
          type: string
          format: date-time
        
    CreateUserRequest:
      type: object
      required:
        - email
        - name
      properties:
        email:
          type: string
          format: email
        name:
          type: string
          minLength: 1
          maxLength: 100

Phase 3: Data Architecture

Module Data Ownership

Each module owns its data completely:

Cross-Module Data Access

• No Direct Database Access: Modules never access other modules' databases directly
• API-Only Integration: All cross-module data access through APIs
• Data Replication: Cache frequently accessed data from other modules
• Event Synchronization: Use events to maintain data consistency

Phase 4: GenAI Integration by Module

LLM-for-Dev Track Integration

Each module benefits from development acceleration:

User Module Development

• AI-assisted API endpoint generation
• Automated test case creation for authentication flows
• Security vulnerability analysis for user data handling

Content Module Development

• AI-generated content management APIs
• Automated search functionality implementation
• Performance optimization suggestions

Payment Module Development

• AI-assisted compliance checking
• Automated invoice generation logic
• Security audit assistance

LLM-in-Product Track Integration

Each module can incorporate user-facing AI features:

Implementation Checklist

Module Definition Phase

• Identify business capabilities and their boundaries
• Map dependencies between modules
• Define module responsibilities and ownership
• Create module interface specifications

Development Phase

• Implement module APIs with proper versioning
• Create comprehensive test suites for each module
• Establish monitoring and logging for module interactions
• Document module architecture and usage patterns

Integration Phase

• Implement inter-module communication patterns
• Set up event-driven architecture for async operations
• Create shared infrastructure services (logging, monitoring, caching)
• Establish deployment and scaling strategies for each module

GenAI Enhancement Phase

• Integrate LLM-for-Dev tools into each module's development workflow
• Implement LLM-in-Product features appropriate to each module
• Create module-specific prompt libraries and AI configurations
• Monitor AI feature performance and user adoption

Benefits and Trade-offs

Benefits

• Clear Ownership: Teams can own complete business capabilities
• Independent Scaling: Scale modules based on business needs
• Technology Diversity: Different modules can use optimal technology stacks
• Reduced Complexity: Smaller, focused codebases are easier to understand
• Faster Development: Parallel development of different business capabilities

Trade-offs

• Integration Complexity: More complex inter-module communication
• Data Consistency: Eventual consistency challenges across modules
• Operational Overhead: More components to monitor and deploy
• Performance: Network latency for cross-module calls
• Testing Complexity: Integration testing across multiple modules

Mitigation Strategies

• Start Simple: Begin with modular monolith, evolve to microservices
• Invest in Tooling: Automated testing, monitoring, and deployment tools
• Clear Contracts: Well-defined interfaces and service level agreements
• Event-Driven Architecture: Reduce coupling through asynchronous communication
• Shared Infrastructure: Common patterns for logging, monitoring, and security

Evolution Path

From Monolith to Modules

Success Metrics

• Development Velocity: Faster feature delivery per module
• System Reliability: Isolated failures don't cascade
• Team Productivity: Clear ownership and reduced coordination overhead
• Business Agility: Ability to evolve business capabilities independently

Ready to implement module-based architecture? Start with Phase 1: Module Identification and work systematically through each implementation phase.