Edmonds Commerce - Legacy Code Documentation
Overview
Code archaeology, architecture diagrams, and knowledge transfer. Reconstruct system architecture and business logic from undocumented legacy codebases.
The Documentation Problem
Missing Knowledge
Legacy systems often lack documentation:
- No architecture diagrams
- Business logic undocumented
- Design decisions unknown
- Data flow unmapped
- Dependencies unclear
Knowledge Volatility
Institutional knowledge is fragile:
- Original developers have moved on
- Tribal knowledge lost with staff turnover
- Onboarding takes months
- New developers afraid to modify
- Decisions repeated from scratch
Code Archaeology Process
What Is Code Archaeology?
Systematic reverse-engineering of legacy systems through code analysis, interviews, and testing.
Goal: Reconstruct architecture and business logic from code.
Our Documentation Approach
Phase 1: Code Analysis
Systematic code review and analysis.
Analysis Includes:
- Entry point identification
- Request flow tracing
- Class and function mapping
- Dependency analysis
- Circular dependency detection
- Code patterns identification
Phase 2: Architecture Reconstruction
Map discovered patterns into architecture diagrams.
Deliverables:
- System architecture diagram
- Component relationships
- Module dependencies
- Data flow diagram
- Request flow diagram
- External system integration points
Phase 3: Business Logic Documentation
Document discovered business rules.
Documentation Includes:
- Business process flows
- Decision logic flows
- Constraint documentation
- Calculation logic
- Workflow documentation
- Edge case handling
Phase 4: Stakeholder Interviews
Gather missing context from people who know the system.
Interviews:
- Original architects
- Long-term developers
- Business stakeholders
- Support staff
- System administrators
Phase 5: Validation
Verify accuracy of reconstructed knowledge.
Validation:
- Walk-through with subject matter experts
- Test reconstructed flows
- Verify assumptions
- Identify contradictions
Phase 6: Knowledge Transfer
Train your team on discovered knowledge.
Training Sessions:
- Architecture overview
- Common workflows
- Data model explanation
- Common pitfalls
- Troubleshooting guide
Documentation Deliverables
Architecture Diagrams
Visual representation of system structure.
Diagrams Include:
- System architecture (high-level)
- Module relationships
- Component interactions
- Data flow
- Request flow
- External system integrations
Business Process Documentation
Describe key business processes and workflows.
Processes Documented:
- User signup/onboarding
- Order processing
- Payment flows
- Reporting workflows
- Batch processes
- Integration points
Data Model Documentation
Explain database and data structure.
Documentation Includes:
- Entity relationship diagram (ERD)
- Table descriptions
- Key relationships
- Data constraints
- Indexing strategy
- Performance considerations
API/Interface Documentation
Document external-facing interfaces.
Interfaces Documented:
- REST API endpoints
- SOAP services
- Webhooks
- Payment gateway integration
- Third-party API integration
- Custom protocols
Deployment & Configuration Guide
Explain how to deploy and configure the system.
Guides Include:
- System requirements
- Installation steps
- Configuration options
- Environment variables
- Database setup
- Initial data loading
Troubleshooting Guide
Common issues and solutions.
Covers:
- Common errors and fixes
- Debug strategies
- Performance tuning
- Connection issues
- Database problems
- Log interpretation
Code Walkthrough Documentation
Documented code tours through critical paths.
Walkthroughs:
- User signup process (code-level)
- Order processing (code-level)
- Payment processing (code-level)
- Critical calculations
- Error handling flows
Documentation Standards
Format
Preferred Formats:
- Markdown for text documentation
- PlantUML or Lucidchart for diagrams
- Sequence diagrams for flows
- Entity-relationship diagrams for data models
Version Control
Management:
- Documentation in version control (Git)
- Linked to code commits
- Updated with architectural changes
- Reviewed with code reviews
Maintenance
Ongoing Maintenance:
- Update as system evolves
- Assign ownership
- Quarterly review
- Community contribution
Typical Architecture Patterns Discovered
Monolithic Architecture
All functionality in single codebase.
Characteristics:
- Single database
- Tightly coupled modules
- Complex interdependencies
- Difficult to scale individual components
Layered Architecture
Separated into layers (presentation, business, data).
Characteristics:
- Request flows through layers
- Clear separation of concerns
- Easier to understand than monoliths
- Still may have tight coupling
MVC Architecture
Model-View-Controller pattern.
Characteristics:
- Controllers handle requests
- Models represent business logic
- Views render responses
- Clear separation of concerns
Service-Oriented
Multiple services with defined boundaries.
Characteristics:
- Service interfaces
- Message passing
- Loose coupling
- Easier to understand and modify
Documentation by System Type
E-Commerce System
- Product catalog data model
- Order processing workflow
- Payment gateway integration
- Inventory management
- Customer account management
Content Management System
- Content model and relationships
- Publishing workflow
- User permissions model
- Content versioning
- Media management
Business Application
- Data entry workflows
- Business logic rules
- Report generation
- Integration points
- User roles and permissions
Timeline & Effort
For 50k LOC Legacy System:
- Code analysis: 2-3 weeks
- Architecture reconstruction: 2-3 weeks
- Documentation writing: 2-3 weeks
- Interviews & validation: 1-2 weeks
- Knowledge transfer training: 1 week
- Total: 8-12 weeks
Documentation Maintenance
Keep Documentation Current
Discipline:
- Update documentation with architectural changes
- Include diagram updates in code reviews
- Quarterly documentation review
- Remove obsolete documentation
- Archive old versions
Knowledge Transfer
Ongoing:
- New team member onboarding with documentation
- Knowledge sharing sessions
- Architecture decision records
- Regular team sync on changes
Target Audiences
Newly Acquired Teams: Understand unfamiliar systems quickly.
Growing Development Teams: Onboard new developers faster.
Leadership Transition: Preserve knowledge as leadership changes.
System Migration: Document before modernising or replacing.
Compliance: Document systems for audit and certification.
Common Documentation Gaps
No Architecture Diagram: Can't see system structure clearly.
No Data Model: Don't understand data relationships.
No Business Logic Documentation: Can't understand "why" code does what it does.
No API Documentation: Third-party integrations undocumented.
No Deployment Guide: Can't reproduce environment or troubleshoot.
No Decision Record: Don't know why design decisions were made.
Benefits of Documentation
Faster Onboarding: New developers productive in days instead of months.
Reduced Risk: Understand impact before modifying.
Preserved Knowledge: Survive staff turnover.
Better Decisions: Understand why decisions were made.
Improved Collaboration: Team understands system structure.
Faster Problem Solving: Know where to look for bugs.
Knowledge Transfer Sessions
Format:
- 1-2 hour sessions with subject matter experts
- Walk through key workflows
- Q&A for understanding
- Recorded for reference
- Documented with diagrams
Related Services
Legacy Assessment: Understand system quality before documenting.
Refactoring: Improve code as you document.
Architecture Review: Expert analysis of reconstructed architecture.
Training: Knowledge transfer sessions for your team.
Contact
Based in the UK, serving global clients. Discuss your documentation needs, system archaeology, or knowledge transfer requirements.