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Netflix System Design

Netflix is a streaming service that provides on-demand video content to millions of users worldwide. Let's analyze its system design.

System Requirements​

Functional Requirements​

  • User authentication and profiles
  • Video streaming
  • Content recommendations
  • Search functionality
  • User preferences and watch history

Non-Functional Requirements​

  • High availability (99.99%)
  • Low latency streaming
  • Global content delivery
  • Scalability for peak loads
  • Data consistency

Architecture​

High-Level Design​

┌─────────────┐     ┌─────────────┐     ┌─────────────┐
│  Client     │     │  API        │     │  Services   │
│  Apps       │────▶│  Gateway    │────▶│  Layer      │
└─────────────┘     └─────────────┘     └─────────────┘
                           │                   │
                           ▼                   ▼
                    ┌─────────────┐     ┌─────────────┐
                    │  CDN        │     │  Storage    │
                    │  Network    │     │  Layer      │
                    └─────────────┘     └─────────────┘

Components​

  1. Client Applications

    • Web browsers
    • Mobile apps
    • Smart TV apps
    • Game consoles

  2. API Gateway

    • Request routing
    • Authentication
    • Rate limiting
    • Load balancing

  3. Microservices

    • User Service
    • Content Service
    • Recommendation Service
    • Search Service
    • Playback Service

  4. Content Delivery

    • AWS CloudFront
    • Netflix Open Connect
    • Edge servers
    • Caching strategy

  5. Storage

    • S3 for video storage
    • Cassandra for user data
    • Redis for caching
    • Elasticsearch for search

Data Models​

User Profile​

{
  "user_id": "123",
  "email": "[email protected]",
  "profiles": [
    {
      "profile_id": "p1",
      "name": "John",
      "preferences": {
        "language": "en",
        "maturity_level": "PG-13"
      },
      "watch_history": [
        {
          "content_id": "movie123",
          "timestamp": "2023-01-01T00:00:00Z",
          "progress": 3600
        }
      ]
    }
  ]
}

Content​

{
  "content_id": "movie123",
  "title": "Example Movie",
  "type": "movie",
  "genres": ["Action", "Adventure"],
  "languages": ["en", "es"],
  "qualities": ["SD", "HD", "4K"],
  "segments": [
    {
      "segment_id": "s1",
      "quality": "HD",
      "url": "https://cdn.netflix.com/movie123/HD/s1"
    }
  ]
}

Key Features​

Video Streaming​

  1. Adaptive Bitrate Streaming

    • Multiple quality levels
    • Dynamic switching
    • Bandwidth detection
    • Buffer management

  2. Content Delivery

    • Edge caching
    • Pre-fetching
    • Regional distribution
    • Load balancing

Recommendation System​

  • Collaborative filtering
  • Content-based filtering
  • Machine learning models
  • A/B testing

Scaling Strategies​

Content Delivery​

  • Global CDN network
  • Edge servers
  • Caching at multiple levels
  • Predictive pre-loading

Database Scaling​

  • Sharding by region
  • Read replicas
  • Caching layer
  • Data partitioning

Challenges​

  1. Content Delivery

    • Bandwidth management
    • Quality of service
    • Regional restrictions
    • Cost optimization

  2. Personalization

    • Real-time recommendations
    • User privacy
    • Data consistency
    • Performance

  3. Global Scale

    • Regional compliance
    • Content licensing
    • Network latency
    • Infrastructure costs

Further Reading​