Architecture Format

Architecture Document Structure

Your architecture must contain the following sections:

1. Task Description

Link to TASK and brief summary of requirements

2. Functional Architecture

Description of the system in terms of functions it performs.

2.1. Functional Components

For each functional component describe:

Component Name: [Example, "User Management"]

Purpose: [Why this component is needed]

Functions:

• Function 1: [Description]

  • Input: [what accepts]
  • Output: [what returns]
  • Related Use Cases: [UC-01, UC-03]

• Function 2: [Description]

  • Input: [what accepts]
  • Output: [what returns]
  • Related Use Cases: [UC-02]

Dependencies:

• Depends on which other components
• Which components depend on it

2.2. Functional Components Diagram

[Mermaid diagram showing connections between components]

3. System Architecture

Description of the system in terms of physical/logical components.

3.1. Architectural Style

Which architectural pattern is used:

• Monolith
• Microservices
• Layered Architecture
• Event-driven
• Etc.

Justification: [Why this style was chosen]

3.2. System Components

For each system component describe:

Component Name: [Example, "User Service"]

Type: [Backend service / Frontend / Database / Message Queue / etc.]

Purpose: [Why needed]

Implemented Functions: [Links to functions from functional architecture]

Technologies: [Programming language, frameworks]

Interfaces:

• Inbound: [Who and how accesses this component]
• Outbound: [Who and how this component accesses]

Dependencies:

• External libraries
• Other system components
• External services

3.3. Components Diagram

[Mermaid diagram showing components and their interaction]

4. Data Model

Description of data structure in the system.

4.1. Conceptual Data Model

Description of main entities and their relationships at a high level.

Entities:

Entity: [Name, e.g., "User"]

Description: [What this entity represents]

Attributes:

• id (UUID) — unique identifier
• email (String, unique) — user email
• password_hash (String) — password hash
• created_at (DateTime) — creation date
• status (Enum: pending, active, blocked) — account status

Relationships:

• One User has many Sessions (1:N)
• One User has one Profile (1:1)

Business Rules:

• Email must be unique
• Password must be at least 8 characters
• Default status — pending

Entity: [Next entity]

...

4.2. Logical Data Model

More detailed description considering storage technology.

For Relational DB:

Table: users

Indexes:

• PRIMARY KEY on id
• UNIQUE INDEX on email
• INDEX on status (for filtering)

Foreign Keys:

• None

For NoSQL DB:

Collection: users

{
  "_id": "ObjectId",
  "email": "string (unique)",
  "password_hash": "string",
  "created_at": "ISODate",
  "updated_at": "ISODate",
  "status": "string (enum: pending, active, blocked)",
  "profile": {
    "first_name": "string",
    "last_name": "string",
    "avatar_url": "string"
  },
  "sessions": [
    {
      "token": "string",
      "created_at": "ISODate",
      "expires_at": "ISODate"
    }
  ]
}

Indexes:

• Unique index on email
• Index on status
• TTL index on sessions.expires_at

4.3. Data Model Diagram

[ER-diagram in PlantUML format]

Example:
┌─────────────┐         ┌─────────────┐
│    User     │         │   Session   │
├─────────────┤         ├─────────────┤
│ id (PK)     │────────<│ user_id(FK) │
│ email       │    1:N  │ token       │
│ password    │         │ expires_at  │
└─────────────┘         └─────────────┘

4.4. Migrations and Versioning

Migration Strategy: [How DB schema changes will be executed]

For modification of existing system:

• Which tables/collections to add
• Which fields to add to existing tables
• Which indexes to create
• Data migration plan (if needed)

5. Interfaces

5.1. External APIs

For each external API describe:

API: [Name, e.g. "User Management API"]

Protocol: REST / GraphQL / gRPC / WebSocket

Base URL: /api/v1/users

Authentication: JWT Bearer Token

Endpoints:

POST /register

Description: New user registration

Related Use Case: UC-01

Request:

{
  "email": "string (required, email format)",
  "password": "string (required, min 8 chars)",
  "password_confirmation": "string (required)"
}

Response 201 Created:

{
  "user_id": "uuid",
  "email": "string",
  "status": "pending",
  "message": "Confirmation email sent"
}

Response 400 Bad Request:

{
  "error": "validation_error",
  "details": {
    "email": ["Email already exists"],
    "password": ["Password too short"]
  }
}

Response 500 Internal Server Error:

{
  "error": "internal_error",
  "message": "Failed to send confirmation email"
}

GET /users/{id}

[Description of next endpoint]

5.2. Internal Interfaces

Description of interaction between system components.

Interface: UserService → EmailService

Protocol: Message Queue (RabbitMQ)

Exchange: notifications

Routing Key: email.confirmation

Message Format:

{
  "user_id": "uuid",
  "email": "string",
  "confirmation_token": "string",
  "template": "user_confirmation"
}

5.3. Integrations with External Systems

If system integrates with external services:

Integration: Email Service (SendGrid)

Purpose: Sending email notifications

Protocol: REST API

Authentication: API Key

Endpoints Used:

• POST /v3/mail/send — send email

Error Handling:

• Retry with exponential backoff
• Maximum 3 attempts
• Logging of failed sends

6. Technology Stack

6.1. Backend

Programming Language: [Python / Java / Node.js / etc.]

Framework: [Django / Spring Boot / Express / etc.]

Justification: [Why these technologies were chosen]

6.2. Frontend (if applicable)

Framework: [React / Vue / Angular / etc.]

Justification:

6.3. Database

Type: [PostgreSQL / MongoDB / Redis / etc.]

Justification:

6.4. Infrastructure

Containerization: Docker

Orchestration: Kubernetes / Docker Compose

Message Queue: RabbitMQ / Kafka / Redis

Caching: Redis / Memcached

Monitoring: Prometheus + Grafana

Logging: ELK Stack / Loki

6.5. For Modification of Existing Project

Used Technologies: [List of technologies already in project]

New Technologies: [What needs to be added and why]

Compatibility: [How new technologies integrate with existing ones]

7. Security

7.1. Authentication and Authorization

Auth Mechanism: JWT / OAuth 2.0 / Session-based

Password Storage: Bcrypt / Argon2

Session Management:

• Token lifetime
• Refresh tokens
• Token revocation mechanism

7.2. Data Protection

Encryption:

• At rest: DB encryption
• In transit: TLS/SSL

Personal Data:

• What data is considered personal
• How it is protected
• GDPR compliance (if applicable)

7.3. Attack Protection

OWASP Top 10:

• SQL Injection: using parameterized queries
• XSS: input sanitization
• CSRF: CSRF tokens
• Etc.

Rate Limiting:

• Request limits
• DDoS protection

8. Scalability and Performance

8.1. Scaling Strategy

Horizontal Scaling:

• Which components can be scaled horizontally
• How load balancing is ensured

Vertical Scaling:

• Which components require vertical scaling

8.2. Caching

What is cached:

• Static data
• Frequent query results
• User sessions

Cache Invalidation Strategy:

8.3. DB Optimization

Indexes: [Which indexes are critical for performance]

Partitioning: [If applicable]

Replication: [Master-Slave, Master-Master]

9. Reliability and Fault Tolerance

9.1. Error Handling

Strategy:

• Graceful degradation
• Circuit breaker pattern
• Retry logic

9.2. Backup

What is backed up:

• Database
• User files
• Configuration

Backup Frequency:

Backup Storage:

9.3. Monitoring and Alerting

Metrics:

• API response time
• Error count
• Resource usage

Alerts:

• Conditions for sending
• Where sent

10. Deployment

10.1. Environments

Development: [Description of dev environment]

Staging: [Description of staging environment]

Production: [Description of prod environment]

10.2. CI/CD Pipeline

Stages:

1. Build
2. Unit Tests
3. Integration Tests
4. Deploy to Staging
5. E2E Tests
6. Deploy to Production

Tools:

• CI/CD: GitHub Actions / GitLab CI / Jenkins
• Deployment: Kubernetes / Docker Swarm / AWS ECS

10.3. Configuration

Configuration Management:

• Environment variables
• Config files
• Secrets management (Vault / AWS Secrets Manager)

10.4. Deployment Instructions

For New Project:

1. Step 1: [Description]
2. Step 2: [Description] ...

For Modification of Existing Project:

1. Step 1: [Description of changes]
2. Step 2: [DB migrations]
3. Step 3: [Configuration update] ...

11. Open Questions

List of questions requiring clarification from user.