MegaTodo

1. Project Overview

Objective: Build a full-featured TODO application to master Golang enterprise development patterns and ecosystem tools

Key Focus Areas:

• Microservices architecture
• Distributed systems patterns
• Cloud-native development
• Production-grade reliability
• Ecosystem tool integration

2. System Architecture

2.1 High-Level Architecture

graph TD
    A[Client] --> B[API Gateway]
    B --> C[User Service]
    B --> D[Todo Service]
    B --> E[Notification Service]
    B --> F[Analytics Service]
    C <--> G[(PostgreSQL)]
    D <--> G
    D <--> H[(Redis)]
    E <--> I[(Kafka)]
    F <--> J[(Elasticsearch)]
    F <--> K[(InfluxDB)]

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2.2 Backend Service Breakdown

Service	Responsibility	Golang Ecosystem Tools
API Gateway	Request routing, rate limiting, auth	Gin, gRPC-gateway, OPA
User Service	Authentication, RBAC, profiles	Casbin, JWT-Go, GORM
Todo Service	Core todo operations, business logic	Ent, Redis, Zap
File Service	File storage/attachments	MinIO SDK, AWS S3 Go SDK
Notification	Email/SMS/push notifications	NSQ, RabbitMQ, Go-Mail
Analytics	Usage metrics, reporting	Prometheus, OpenTelemetry
Search	Full-text search	Elasticsearch Go Client

3. Core Requirements

3.1 Functional Requirements

3.1.1 User Management

• JWT-based authentication
• OAuth2 social login
• Role-based access control (Admin/User/Guest)
• Audit logging

3.1.2 Todo Management

• CRUD operations with versioning
• Hierarchical todos (Projects > Tasks > Subtasks)
• Due dates/reminders with timezones
• File attachments (PDF/Images)
• Comments/activity feed
• Real-time collaboration

3.1.3 Advanced Features

• Recurring tasks with custom patterns
• Time tracking/pomodoro integration
• Customizable workflows (Kanban/List view)
• Data export (JSON/CSV)
• REST & GraphQL APIs

3.2 Non-Functional Requirements

Category	Requirements	Golang Implementation
Performance	<100ms API response time	fasthttp, connection pooling
Scalability	10k+ concurrent users	Kubernetes, HPA
Reliability	99.99% uptime	Circuit breakers, health checks
Security	OWASP Top 10 compliance	Go-Sec, Vault SDK
Observability	Full request tracing	Jaeger, OpenTelemetry
Maintainability	Clean architecture	Hexagonal architecture

4. Backend Technical Specification

4.1 Core Components

Service Template:

type TodoService struct {
    repo        TodoRepository
    cache       CacheProvider
    eventBus    EventBus
    logger      Logger
    validator   Validator
}

// Example Method
func (s *TodoService) CreateTodo(ctx context.Context, todo *Todo) error {
    // Validation
    if err := s.validator.Struct(todo); err != nil {
        return err
    }
    
    // Database operation
    if err := s.repo.Create(ctx, todo); err != nil {
        return err
    }
    
    // Publish event
    s.eventBus.Publish(TodoCreatedEvent{
        ID:        todo.ID,
        Timestamp: time.Now(),
    })
    
    // Cache warmup
    go s.cache.Set(ctx, todoCacheKey(todo.ID), todo, 5*time.Minute)
    
    return nil
}

4.2 Key Integration Points

Database Layer:

// Using Ent framework
func (r *TodoRepository) FindByID(ctx context.Context, id string) (*Todo, error) {
    return r.client.Todo.
        Query().
        Where(todo.ID(id)).
        WithProject().
        WithSubtasks().
        Only(ctx)
}

Event Streaming:

// Kafka producer setup
func NewEventBus(cfg Config) (EventBus, error) {
    producer, err := kafka.NewProducer(&kafka.ConfigMap{
        "bootstrap.servers": cfg.KafkaBrokers,
    })
    // ...
}

// Event consumption
func (s *TodoService) ConsumeEvents() {
    consumer.Subscribe("todo-events", nil)
    for {
        msg, _ := consumer.ReadMessage()
        var event TodoEvent
        json.Unmarshal(msg.Value, &event)
        s.handleEvent(event)
    }
}

5. Development Roadmap

Phase 1: Core System (2 Weeks)

gantt
    title Phase 1: Core System
    dateFormat  YYYY-MM-DD
    section Infrastructure
    API Gateway       :done, infra1, 2024-01-01, 3d
    Service Template  :done, infra2, after infra1, 2d
    section User Service
    JWT Auth          :active, auth1, 2024-01-04, 3d
    RBAC System       :          auth2, after auth1, 2d
    section Todo Service
    CRUD API          :          todo1, 2024-01-04, 5d
    Database Schema   :          todo2, 2024-01-04, 3d

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Phase 2: Distributed Features (3 Weeks)

• Real-time collaboration
• File service integration
• Notification system
• Basic monitoring

Phase 3: Enterprise Patterns (4 Weeks)

• Service mesh integration
• Advanced security features
• Auto-scaling implementation
• Chaos engineering tests

6. Learning Outcomes

Golang Ecosystem Mastery:

pie
    title Technology Coverage
    "Web Frameworks" : 15
    "Database Tools" : 20
    "Distributed Systems" : 25
    "Cloud Native" : 20
    "Observability" : 10
    "Testing" : 10

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Key Competencies Developed:

1. Microservices communication patterns (gRPC, REST)
2. Event-driven architecture implementation
3. Production-grade error handling
4. Performance optimization techniques
5. Cloud-native deployment strategies
6. Distributed system debugging

7. Quality Attributes

Attribute	Implementation Strategy	Verification Method
Scalability	Horizontal pod autoscaling	Load testing with Vegeta
Resilience	Circuit breaker pattern	Chaos monkey testing
Security	Automated vulnerability scanning	OWASP ZAP integration
Maintainability	Strict interface contracts	API contract testing
Deployability	GitOps workflow	ArgoCD rollout verification

8. Documentation Strategy

• OpenAPI 3.0 specifications
• Architecture Decision Records (ADRs)
• GoDoc generated documentation
• Postman collection for API testing
• Operational runbooks