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Diagram Creation with Mermaid

Master the art of visual architecture documentation using Mermaid diagrams. This module teaches you to create clear, maintainable diagrams that communicate complex technical concepts effectively.

Learning Objectives​

After completing this module, you will be able to:

✅ Create System Architecture Diagrams - Visualize complex system relationships
✅ Design Database Entity Relationships - Model data structures and relationships
✅ Document API Flows - Show request/response patterns and sequences
✅ Generate Diagrams with AI - Use AI tools to accelerate diagram creation
✅ Maintain Living Documentation - Keep diagrams synchronized with implementation

Why Diagrams Matter​

The Visual Documentation Advantage:

  • Visual processing is 60,000x faster than text processing
  • Diagrams reduce architectural misunderstandings by 80%
  • Teams with visual docs deliver features 40% faster
  • Bug reduction of up to 60% with clear system diagrams

Mermaid Fundamentals​

Why Mermaid for GISE?​

Mermaid Benefits for GISE:

  • Text-based: Perfect for version control and Git workflows
  • AI-friendly: LLMs can generate and modify Mermaid syntax
  • Live editing: Real-time preview and iteration
  • Wide support: GitHub, GitLab, Notion, and many documentation tools

Basic Mermaid Syntax​

Flowchart Basics:

Syntax Elements:

  • graph TD - Top Down flowchart
  • A[Rectangle] - Process or component
  • B{Diamond} - Decision point
  • --> - Connection/flow
  • |Text| - Connection labels

System Architecture Diagrams​

High-Level System Overview​

Purpose: Show major components and their relationships

Template for System Architecture:

Component Interaction Diagrams​

Purpose: Show detailed interactions between specific components

Sequence Diagram Best Practices:

  • Start with the user action that triggers the flow
  • Show all components involved in the process
  • Include both successful and error paths
  • Add timing considerations if relevant

Service Architecture Patterns​

Microservices Architecture:

Database Design Diagrams​

Entity Relationship Diagrams​

Purpose: Show data models, relationships, and constraints

ERD Best Practices:

  • Use clear, descriptive entity names
  • Show primary keys (PK) and foreign keys (FK)
  • Include unique constraints (UK) where relevant
  • Add cardinality indicators (||--o{)
  • Include important attributes and data types

Database Schema Evolution​

Show how your schema changes over time:

API Documentation Diagrams​

API Flow Diagrams​

REST API Patterns:

Authentication Flows​

OAuth 2.0 Flow Visualization:

State Diagrams​

Application State Management​

User Session States:

Business Process States​

Project Lifecycle:

AI-Assisted Diagram Creation​

Prompt Templates for Diagram Generation​

System Architecture Prompt:

Create a Mermaid diagram showing the system architecture for:

PROJECT DESCRIPTION:
[Describe your system and key requirements]

COMPONENTS NEEDED:
- [List main components]
- [Data storage requirements]
- [External integrations]

REQUIREMENTS:
- [Performance requirements]
- [Security requirements]
- [Scalability requirements]

Generate a clear Mermaid graph TB diagram showing:
1. Component groupings (using subgraphs)
2. Data flow between components
3. External dependencies
4. Appropriate icons/styling for different component types

Focus on clarity and maintainability.

Database ERD Prompt:

Create a Mermaid ERD for this data model:

BUSINESS DOMAIN:
[Describe the business area]

ENTITIES NEEDED:
- [List main entities and their purposes]
- [Relationships between entities]
- [Key attributes for each entity]

CONSTRAINTS:
- [Business rules]
- [Data validation requirements]
- [Performance considerations]

Generate a Mermaid erDiagram that shows:
1. All entities with key attributes
2. Primary keys (PK) and foreign keys (FK)
3. Relationship cardinality
4. Important constraints and indexes

Include data types where relevant.

API Flow Prompt:

Create a Mermaid sequence diagram for this API interaction:

ENDPOINT: [API endpoint]
METHOD: [HTTP method]
PURPOSE: [What this API does]

COMPONENTS INVOLVED:
- [List all services/components in the flow]
- [External dependencies]

SUCCESS FLOW:
- [Step-by-step successful interaction]

ERROR SCENARIOS:
- [Common error cases to show]

Generate a clear sequenceDiagram showing:
1. All participants in the interaction
2. Request/response flow with appropriate labels
3. Error handling paths
4. Any async operations or side effects

Focus on completeness and clarity.

AI Tools for Diagram Creation​

ToolBest ForPrompt Strategy
ChatGPT/ClaudeComplex architecture diagramsDetailed requirements, iterative refinement
GitHub CopilotExtending existing diagramsContext-aware completion
CursorDiagram editing and refinementInline suggestions and improvements
Mermaid Live EditorReal-time validationDirect editing with live preview

Iterative Diagram Improvement​

Refinement Process:

  1. Generate Initial Diagram - Use AI with comprehensive prompt
  2. Review and Validate - Check against requirements
  3. Refine Details - Add missing components or connections
  4. Optimize Layout - Improve visual clarity and grouping
  5. Validate with Team - Get feedback from stakeholders
  6. Update Documentation - Sync with related documentation

Advanced Diagram Patterns​

Multi-Layer Architecture​

Clean Architecture Visualization:

Deployment Architecture​

Container Orchestration:

Diagram Maintenance and Evolution​

Version Control for Diagrams​

Git Integration Best Practices:

# Directory structure for diagrams
docs/
├── architecture/
│   ├── system-overview.mmd
│   ├── component-details.mmd
│   └── deployment.mmd
├── database/
│   ├── schema-v1.mmd
│   ├── schema-v2.mmd
│   └── migrations.mmd
└── api/
    ├── authentication-flow.mmd
    ├── user-management.mmd
    └── project-workflow.mmd

Living Documentation​

Keep Diagrams Current:

  • Link to Code - Reference actual implementation files
  • Automated Validation - Check diagram accuracy in CI/CD
  • Regular Reviews - Schedule diagram review sessions
  • Change Notifications - Update diagrams when architecture changes

Diagram Validation Checklist:

  • All components shown exist in implementation
  • Data flows match actual API calls
  • Security boundaries are accurately represented
  • Performance characteristics are current
  • External dependencies are up-to-date

Diagram Quality Standards​

Clarity Standards:

  • Clear Labels - Every component and connection labeled
  • Consistent Styling - Use standard shapes and colors
  • Appropriate Granularity - Right level of detail for audience
  • Logical Grouping - Related components grouped together

Maintainability Standards:

  • Source Control - All diagrams in version control
  • Documentation - Purpose and context documented
  • Update Process - Clear process for keeping current
  • Team Knowledge - Multiple team members can maintain

Troubleshooting Common Diagram Issues​

Performance Problems​

Issue: Diagrams are too complex or slow to render Solutions:

  • Break large diagrams into smaller, focused diagrams
  • Use subgraphs to organize complex relationships
  • Limit the number of nodes and connections per diagram
  • Create drill-down diagrams for detailed views

Clarity Issues​

Issue: Diagrams are confusing or hard to follow Solutions:

  • Use consistent naming conventions
  • Group related components with subgraphs
  • Add descriptive labels to connections
  • Use appropriate diagram types for the information

Maintenance Burden​

Issue: Diagrams become outdated quickly Solutions:

  • Integrate diagram updates into development workflow
  • Create automated checks for diagram accuracy
  • Assign diagram ownership to specific team members
  • Keep diagrams close to related code in repository

Next Steps​

Continue Your Design Journey​

  1. Technical Blueprints - Create comprehensive technical specifications
  2. Pull Request Reviews - Implement design review processes
  3. API Specification - Learn OpenAPI documentation

Practice Your Skills​

Reference Materials​

Remember: The best diagram is the one that clearly communicates your architecture to both current and future team members. Focus on clarity over complexity.