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Server Architecture

Overview

The R-Type server implements an authoritative game server architecture using UDP for network communication. It manages game state, processes player inputs, and synchronizes the game world across all connected clients.

Key Features

  • ECS-Based Architecture: Pure Entity Component System for game logic
  • UDP Protocol: Low-latency network communication
  • Component Snapshots: Efficient state synchronization
  • Delta Encoding: Bandwidth optimization for large game worlds
  • Authoritative Server: Server-side validation
  • Bidirectional Simulation: Both server and client run simulations

Components

Network Layer

The server uses a custom binary protocol over UDP for real-time communication:

  • Connection Management: Handle client connections and disconnections
  • Reliability Layer: Optional reliable delivery for critical packets
  • Packet Processing: Efficient serialization and deserialization

See Protocol Documentation for detailed specifications.

Game Simulation

The server runs a fixed-timestep simulation loop:

┌─────────────────────────────────┐
│   Server Tick (60 Hz)           │
├─────────────────────────────────┤
│ 1. Process Input Packets        │
│ 2. Update ECS Systems           │
│ 3. Detect Collisions            │
│ 4. Generate Component Snapshots │
│ 5. Send to Clients              │
└─────────────────────────────────┘

State Synchronization

The server uses component-based snapshots with different update frequencies:

Component Frequency Reason
Transform 60 Hz Critical for smooth movement
Velocity 30 Hz Predictable, can interpolate
Health 20 Hz Changes infrequently
Weapon 10 Hz Changes on events only
AI 5 Hz Highly predictable

Architecture Diagrams

Client-Server Communication Flow

Client                          Server
  │                               │
  ├─── CLIENT_CONNECT ──────────>│
  │                               ├─── Validate
  │<────── SERVER_ACCEPT ─────────┤
  │                               │
  ├─── PLAYER_INPUT (60Hz) ─────>│
  │                               ├─── Update Simulation
  │<── TRANSFORM_SNAPSHOT (60Hz)─┤
  │<── HEALTH_SNAPSHOT (20Hz) ───┤
  │<── GAME_EVENTS ──────────────┤
  │                               │
  ├─── HEARTBEAT (1Hz) ─────────>│
  │                               │

ECS Component Updates

┌──────────────────────────────────────────────┐
│          Server ECS Systems                  │
├──────────────────────────────────────────────┤
│                                              │
│  InputSystem ────> TransformSystem           │
│                          │                   │
│  PhysicsSystem ──────────┤                   │
│                          │                   │
│  AISystem ───────────────┤                   │
│                          ▼                   │
│                    CollisionSystem           │
│                          │                   │
│  WeaponSystem ───────────┤                   │
│                          │                   │
│                          ▼                   │
│                  Network Snapshot            │
│                     Generator                │
│                          │                   │
│                          ▼                   │
│                  Send to Clients             │
└──────────────────────────────────────────────┘

Performance Considerations

Bandwidth Optimization

The server implements several bandwidth optimization techniques:

  1. Delta Snapshots: Only send changed entities

  2. Example: 5/40 entities moving = 84% bandwidth reduction

  3. Component Frequency Tuning: Update rates based on criticality

  4. Critical (Transform): 60 Hz

  5. Non-critical (AI): 5 Hz

  6. Interest Management: Send only relevant entities to each client

  7. Spatial partitioning
  8. Visibility culling

Scalability

The server is designed to handle:

  • Players: Up to 4 concurrent players per game instance
  • Entities: 100-200 active entities per game
  • Tick Rate: 60 updates per second
  • Bandwidth: ~50 KB/s per client (optimized)

Configuration

Server configuration includes:

struct ServerConfig {
    uint16_t port;                  // Default: 4242
    uint8_t  max_players;           // Default: 2
    uint16_t tick_rate;             // Default: 60 Hz
    uint16_t snapshot_rate;         // Default: 30 Hz
    uint32_t timeout_ms;            // Default: 10000 ms
    bool     enable_delta_encoding; // Default: false
};

Getting Started

For information on how to build and run the server, see the main README.