Architecture Documentation

In This Document

• In This Document
• Architecture Documentation Purpose
• Required Architecture Documentation
  • System Overview
  • Component Documentation
  • Data Architecture
• Architecture Diagrams
  • Context Diagrams
  • Component Diagrams
  • Sequence Diagrams
  • Deployment Diagrams
• Architecture Decision Records (ADRs)
  • ADR Format
  • When to Create an ADR
• Documentation Tools and Standards
  • Recommended Tools
  • Naming Conventions
  • Version Control
• Maintaining Architecture Documentation
  • Review Cycle
  • Ownership
• Integration with Development Process

Architecture Documentation Purpose

Architecture documentation serves several critical purposes for our team:

1. Shared Understanding: Create a common mental model of the system
2. Onboarding: Help new team members understand the system quickly
3. Decision Making: Provide context for future architectural decisions
4. Impact Analysis: Help assess the impact of proposed changes
5. Knowledge Preservation: Capture design decisions and rationale

Required Architecture Documentation

System Overview

Every project must have a system overview document that includes:

• High-level description of the system purpose
• Key architectural patterns used
• Major components and their responsibilities
• External dependencies and integrations
• Deployment architecture

Component Documentation

For each major component:

• Purpose and responsibilities
• Internal structure
• Interfaces with other components
• Key algorithms and data structures
• Performance characteristics
• Security considerations

Data Architecture

Documentation of the data architecture must include:

• Entity-relationship diagrams
• Data flow diagrams
• Database schema documentation
• Data migration strategies
• Data retention policies
• Backup and recovery procedures

Architecture Diagrams

Context Diagrams

Context Diagrams

Context diagrams show the system in its environment, including:

• System boundaries
• External entities
• Key interfaces

Create context diagrams using Mermaid.js or a similar tool.

Component Diagrams

Component Diagrams

Component diagrams show the internal structure of the system:

• Major components
• Component relationships
• Interfaces between components

Component diagrams should be detailed enough to understand relationships but not so detailed that they become unmaintainable.

Sequence Diagrams

Sequence Diagrams

Sequence diagrams show the interactions between components for key processes:

• Component interactions over time
• Message flow
• Conditional logic

Create sequence diagrams for complex or critical processes.

Deployment Diagrams

Deployment Diagrams

Deployment diagrams show the physical deployment of the system:

• Servers and environments
• Network topology
• Load balancers and proxies
• Database clusters

Update deployment diagrams when infrastructure changes.

Architecture Decision Records (ADRs)

We use Architecture Decision Records to document significant architectural decisions:

ADR Format

Each ADR should include:

1. Title: A descriptive title
2. Status: Proposed, Accepted, Deprecated, or Superseded
3. Context: The problem being addressed and relevant constraints
4. Decision: The decision that was made
5. Consequences: The resulting context after applying the decision
6. Alternatives: Options that were considered but not chosen
7. References: Related documents or resources

When to Create an ADR

Create an ADR for decisions that:

• Have a significant impact on the system architecture
• Introduce new architectural patterns or technologies
• Change existing architectural patterns
• Affect multiple components or teams
• Have long-term implications for the system

Documentation Tools and Standards

Recommended Tools

• Mermaid.js: For diagrams embedded in Markdown
• Docusaurus: For hosting architecture documentation
• Draw.io/diagrams.net: For more complex diagrams
• Lucidchart: For collaborative diagramming

Naming Conventions

• Use consistent naming across diagrams and documents
• Match component names in diagrams to code when possible
• Use PascalCase for component names
• Use descriptive, action-oriented names for interactions

Version Control

• Store architecture documentation in the same repository as code
• Version documentation alongside code changes
• Review documentation changes as part of code reviews
• Tag documentation versions with software releases

Maintaining Architecture Documentation

Review Cycle

• Review architecture documentation quarterly
• Update when significant changes are made
• Archive outdated documentation
• Validate diagrams against the current implementation

Ownership

• Assign an owner for each architecture document
• Include documentation updates in feature planning
• Make documentation review part of the release process
• Train team members on documentation standards

Integration with Development Process

Architecture documentation is integrated with our development process:

• Reference architecture documentation in technical designs
• Update documentation as part of feature implementation
• Include documentation review in architectural reviews
• Use architecture diagrams in technical discussions