# Design Document

## Overview

The Multi-Exchange Data Aggregation System is a comprehensive data collection and processing subsystem designed to serve as the foundational data layer for the trading orchestrator. The system will collect real-time order book and OHLCV data from the top 10 cryptocurrency exchanges, aggregate it into standardized formats, store it in a TimescaleDB time-series database, and provide both live data feeds and historical replay capabilities.

The system follows a microservices architecture with containerized components, ensuring scalability, maintainability, and seamless integration with the existing trading infrastructure.

We implement it in the `.\COBY` subfolder for easy integration with the existing system

## Architecture

### High-Level Architecture

```mermaid
graph TB
    subgraph "Exchange Connectors"
        E1[Binance WebSocket]
        E2[Coinbase WebSocket]
        E3[Kraken WebSocket]
        E4[Bybit WebSocket]
        E5[OKX WebSocket]
        E6[Huobi WebSocket]
        E7[KuCoin WebSocket]
        E8[Gate.io WebSocket]
        E9[Bitfinex WebSocket]
        E10[MEXC WebSocket]
    end
    
    subgraph "Data Processing Layer"
        DP[Data Processor]
        AGG[Aggregation Engine]
        NORM[Data Normalizer]
    end
    
    subgraph "Storage Layer"
        TSDB[(TimescaleDB)]
        CACHE[Redis Cache]
    end
    
    subgraph "API Layer"
        LIVE[Live Data API]
        REPLAY[Replay API]
        WEB[Web Dashboard]
    end
    
    subgraph "Integration Layer"
        ORCH[Orchestrator Interface]
        ADAPTER[Data Adapter]
    end
    
    E1 --> DP
    E2 --> DP
    E3 --> DP
    E4 --> DP
    E5 --> DP
    E6 --> DP
    E7 --> DP
    E8 --> DP
    E9 --> DP
    E10 --> DP
    
    DP --> NORM
    NORM --> AGG
    AGG --> TSDB
    AGG --> CACHE
    
    CACHE --> LIVE
    TSDB --> REPLAY
    LIVE --> WEB
    REPLAY --> WEB
    
    LIVE --> ADAPTER
    REPLAY --> ADAPTER
    ADAPTER --> ORCH
```

### Component Architecture

The system is organized into several key components:

1. **Exchange Connectors**: WebSocket clients for each exchange
2. **Data Processing Engine**: Normalizes and validates incoming data
3. **Aggregation Engine**: Creates price buckets and heatmaps
4. **Storage Layer**: TimescaleDB for persistence, Redis for caching
5. **API Layer**: REST and WebSocket APIs for data access
6. **Web Dashboard**: Real-time visualization interface
7. **Integration Layer**: Orchestrator-compatible interface

## Components and Interfaces

### Exchange Connector Interface

```python
class ExchangeConnector:
    """Base interface for exchange WebSocket connectors"""
    
    async def connect(self) -> bool
    async def disconnect(self) -> None
    async def subscribe_orderbook(self, symbol: str) -> None
    async def subscribe_trades(self, symbol: str) -> None
    def get_connection_status(self) -> ConnectionStatus
    def add_data_callback(self, callback: Callable) -> None
```

### Data Processing Interface

```python
class DataProcessor:
    """Processes and normalizes raw exchange data"""
    
    def normalize_orderbook(self, raw_data: Dict, exchange: str) -> OrderBookSnapshot
    def normalize_trade(self, raw_data: Dict, exchange: str) -> TradeEvent
    def validate_data(self, data: Union[OrderBookSnapshot, TradeEvent]) -> bool
    def calculate_metrics(self, orderbook: OrderBookSnapshot) -> OrderBookMetrics
```

### Aggregation Engine Interface

```python
class AggregationEngine:
    """Aggregates data into price buckets and heatmaps"""
    
    def create_price_buckets(self, orderbook: OrderBookSnapshot, bucket_size: float) -> PriceBuckets
    def update_heatmap(self, symbol: str, buckets: PriceBuckets) -> HeatmapData
    def calculate_imbalances(self, orderbook: OrderBookSnapshot) -> ImbalanceMetrics
    def aggregate_across_exchanges(self, symbol: str) -> ConsolidatedOrderBook
```

### Storage Interface

```python
class StorageManager:
    """Manages data persistence and retrieval"""
    
    async def store_orderbook(self, data: OrderBookSnapshot) -> bool
    async def store_trade(self, data: TradeEvent) -> bool
    async def get_historical_data(self, symbol: str, start: datetime, end: datetime) -> List[Dict]
    async def get_latest_data(self, symbol: str) -> Dict
    def setup_database_schema(self) -> None
```

### Replay Interface

```python
class ReplayManager:
    """Provides historical data replay functionality"""
    
    def create_replay_session(self, start_time: datetime, end_time: datetime, speed: float) -> str
    async def start_replay(self, session_id: str) -> None
    async def pause_replay(self, session_id: str) -> None
    async def stop_replay(self, session_id: str) -> None
    def get_replay_status(self, session_id: str) -> ReplayStatus
```

## Data Models

### Core Data Structures

```python
@dataclass
class OrderBookSnapshot:
    """Standardized order book snapshot"""
    symbol: str
    exchange: str
    timestamp: datetime
    bids: List[PriceLevel]
    asks: List[PriceLevel]
    sequence_id: Optional[int] = None
    
@dataclass
class PriceLevel:
    """Individual price level in order book"""
    price: float
    size: float
    count: Optional[int] = None

@dataclass
class TradeEvent:
    """Standardized trade event"""
    symbol: str
    exchange: str
    timestamp: datetime
    price: float
    size: float
    side: str  # 'buy' or 'sell'
    trade_id: str

@dataclass
class PriceBuckets:
    """Aggregated price buckets for heatmap"""
    symbol: str
    timestamp: datetime
    bucket_size: float
    bid_buckets: Dict[float, float]  # price -> volume
    ask_buckets: Dict[float, float]  # price -> volume
    
@dataclass
class HeatmapData:
    """Heatmap visualization data"""
    symbol: str
    timestamp: datetime
    bucket_size: float
    data: List[HeatmapPoint]
    
@dataclass
class HeatmapPoint:
    """Individual heatmap data point"""
    price: float
    volume: float
    intensity: float  # 0.0 to 1.0
    side: str  # 'bid' or 'ask'
```

### Database Schema

#### TimescaleDB Tables

```sql
-- Order book snapshots table
CREATE TABLE order_book_snapshots (
    id BIGSERIAL,
    symbol VARCHAR(20) NOT NULL,
    exchange VARCHAR(20) NOT NULL,
    timestamp TIMESTAMPTZ NOT NULL,
    bids JSONB NOT NULL,
    asks JSONB NOT NULL,
    sequence_id BIGINT,
    mid_price DECIMAL(20,8),
    spread DECIMAL(20,8),
    bid_volume DECIMAL(30,8),
    ask_volume DECIMAL(30,8),
    PRIMARY KEY (timestamp, symbol, exchange)
);

-- Convert to hypertable
SELECT create_hypertable('order_book_snapshots', 'timestamp');

-- Trade events table
CREATE TABLE trade_events (
    id BIGSERIAL,
    symbol VARCHAR(20) NOT NULL,
    exchange VARCHAR(20) NOT NULL,
    timestamp TIMESTAMPTZ NOT NULL,
    price DECIMAL(20,8) NOT NULL,
    size DECIMAL(30,8) NOT NULL,
    side VARCHAR(4) NOT NULL,
    trade_id VARCHAR(100) NOT NULL,
    PRIMARY KEY (timestamp, symbol, exchange, trade_id)
);

-- Convert to hypertable
SELECT create_hypertable('trade_events', 'timestamp');

-- Aggregated heatmap data table
CREATE TABLE heatmap_data (
    symbol VARCHAR(20) NOT NULL,
    timestamp TIMESTAMPTZ NOT NULL,
    bucket_size DECIMAL(10,2) NOT NULL,
    price_bucket DECIMAL(20,8) NOT NULL,
    volume DECIMAL(30,8) NOT NULL,
    side VARCHAR(3) NOT NULL,
    exchange_count INTEGER NOT NULL,
    PRIMARY KEY (timestamp, symbol, bucket_size, price_bucket, side)
);

-- Convert to hypertable
SELECT create_hypertable('heatmap_data', 'timestamp');

-- OHLCV data table
CREATE TABLE ohlcv_data (
    symbol VARCHAR(20) NOT NULL,
    timestamp TIMESTAMPTZ NOT NULL,
    timeframe VARCHAR(10) NOT NULL,
    open_price DECIMAL(20,8) NOT NULL,
    high_price DECIMAL(20,8) NOT NULL,
    low_price DECIMAL(20,8) NOT NULL,
    close_price DECIMAL(20,8) NOT NULL,
    volume DECIMAL(30,8) NOT NULL,
    trade_count INTEGER,
    PRIMARY KEY (timestamp, symbol, timeframe)
);

-- Convert to hypertable
SELECT create_hypertable('ohlcv_data', 'timestamp');
```

## Error Handling

### Connection Management

The system implements robust error handling for exchange connections:

1. **Exponential Backoff**: Failed connections retry with increasing delays
2. **Circuit Breaker**: Temporarily disable problematic exchanges
3. **Graceful Degradation**: Continue operation with available exchanges
4. **Health Monitoring**: Continuous monitoring of connection status

### Data Validation

All incoming data undergoes validation:

1. **Schema Validation**: Ensure data structure compliance
2. **Range Validation**: Check price and volume ranges
3. **Timestamp Validation**: Verify temporal consistency
4. **Duplicate Detection**: Prevent duplicate data storage

### Database Resilience

Database operations include comprehensive error handling:

1. **Connection Pooling**: Maintain multiple database connections
2. **Transaction Management**: Ensure data consistency
3. **Retry Logic**: Automatic retry for transient failures
4. **Backup Strategies**: Regular data backups and recovery procedures

## Testing Strategy

### Unit Testing

Each component will have comprehensive unit tests:

1. **Exchange Connectors**: Mock WebSocket responses
2. **Data Processing**: Test normalization and validation
3. **Aggregation Engine**: Verify bucket calculations
4. **Storage Layer**: Test database operations
5. **API Layer**: Test endpoint responses

### Integration Testing

End-to-end testing scenarios:

1. **Multi-Exchange Data Flow**: Test complete data pipeline
2. **Database Integration**: Verify TimescaleDB operations
3. **API Integration**: Test orchestrator interface compatibility
4. **Performance Testing**: Load testing with high-frequency data

### Performance Testing

Performance benchmarks and testing:

1. **Throughput Testing**: Measure data processing capacity
2. **Latency Testing**: Measure end-to-end data latency
3. **Memory Usage**: Monitor memory consumption patterns
4. **Database Performance**: Query performance optimization

### Monitoring and Observability

Comprehensive monitoring system:

1. **Metrics Collection**: Prometheus-compatible metrics
2. **Logging**: Structured logging with correlation IDs
3. **Alerting**: Real-time alerts for system issues
4. **Dashboards**: Grafana dashboards for system monitoring

## Deployment Architecture

### Docker Containerization

The system will be deployed using Docker containers:

```yaml
# docker-compose.yml
version: '3.8'
services:
  timescaledb:
    image: timescale/timescaledb:latest-pg14
    environment:
      POSTGRES_DB: market_data
      POSTGRES_USER: market_user
      POSTGRES_PASSWORD: ${DB_PASSWORD}
    volumes:
      - timescale_data:/var/lib/postgresql/data
    ports:
      - "5432:5432"
    
  redis:
    image: redis:7-alpine
    ports:
      - "6379:6379"
    volumes:
      - redis_data:/data
    
  data-aggregator:
    build: ./data-aggregator
    environment:
      - DB_HOST=timescaledb
      - REDIS_HOST=redis
      - LOG_LEVEL=INFO
    depends_on:
      - timescaledb
      - redis
    
  web-dashboard:
    build: ./web-dashboard
    ports:
      - "8080:8080"
    environment:
      - API_HOST=data-aggregator
    depends_on:
      - data-aggregator

volumes:
  timescale_data:
  redis_data:
```

### Configuration Management

Environment-based configuration:

```python
# config.py
@dataclass
class Config:
    # Database settings
    db_host: str = os.getenv('DB_HOST', 'localhost')
    db_port: int = int(os.getenv('DB_PORT', '5432'))
    db_name: str = os.getenv('DB_NAME', 'market_data')
    db_user: str = os.getenv('DB_USER', 'market_user')
    db_password: str = os.getenv('DB_PASSWORD', '')
    
    # Redis settings
    redis_host: str = os.getenv('REDIS_HOST', 'localhost')
    redis_port: int = int(os.getenv('REDIS_PORT', '6379'))
    
    # Exchange settings
    exchanges: List[str] = field(default_factory=lambda: [
        'binance', 'coinbase', 'kraken', 'bybit', 'okx',
        'huobi', 'kucoin', 'gateio', 'bitfinex', 'mexc'
    ])
    
    # Aggregation settings
    btc_bucket_size: float = 10.0  # $10 USD buckets for BTC
    eth_bucket_size: float = 1.0   # $1 USD buckets for ETH
    
    # Performance settings
    max_connections_per_exchange: int = 5
    data_buffer_size: int = 10000
    batch_write_size: int = 1000
    
    # API settings
    api_host: str = os.getenv('API_HOST', '0.0.0.0')
    api_port: int = int(os.getenv('API_PORT', '8080'))
    websocket_port: int = int(os.getenv('WS_PORT', '8081'))
```

This design provides a robust, scalable foundation for multi-exchange data aggregation that seamlessly integrates with the existing trading orchestrator while providing the flexibility for future enhancements and additional exchange integrations.