Exchange | Modular Trading Infrastructure

The exchange/ directory contains the core server-side infrastructure for the BetaTrader ecosystem. It is engineered using a Micro-Module Architecture, where each logical component (matching, risk, persistence, networking) is isolated into a standalone C++ library with its own unit tests.

Architecture & System Flow

The Exchange operates as a high-performance, partitioned matching engine. Instead of a single monolithic process, it is a collection of optimized modules orchestrated by the exchange_app daemon.

graph TD
    classDef ui fill:#2b303a,stroke:#4caf50,stroke-width:2px,color:white;
    classDef net fill:#1f2833,stroke:#66fcf1,stroke-width:2px,color:white;
    classDef logic fill:#0b0c10,stroke:#c5c6c7,stroke-width:2px,color:white;
    classDef data fill:#2d142c,stroke:#ee4540,stroke-width:2px,color:white;
 
    subgraph "Networking Gateway"
        FIX[exchange_fix]:::net
    end
 
    subgraph "Orchestration Layer"
        CORE[exchange_app: TradingCore]:::logic
    end
 
    subgraph "Matching Partitions"
        P1[exchange_routing: Partition 1]:::logic
        P2[exchange_routing: Partition 2]:::logic
        
        OB[exchange_matching: OrderBook]:::logic
        MAT[exchange_matching: Matcher]:::logic
        
        P1 --> OB
        P1 --> MAT
    end
 
    subgraph "State & Management"
        RISK[exchange_risk]:::logic
        STATE[exchange_state: ID Generators]:::logic
        PUB[exchange_publishers]:::net
    end
 
    subgraph "Persistence Layer"
        DB[exchange_persistence: DatabaseWorker]:::data
    end
 
    %% Flow
    FIX -->|submitCommand| CORE
    CORE -->|Route by Instrument| P1
    CORE -->|Route by Instrument| P2
    
    P1 -->|Pre-Trade| RISK
    P1 -->|Load/Save| DB
    P1 -->|Next ID| STATE
    
    P1 -->|Executions| PUB
    PUB -->|Callbacks| FIX

The Micro-Modules

Explore the individual README.md files for detailed class diagrams, data structures, and design patterns:

1. **`exchange_app`**: The top-level orchestrator and singleton manager (TradingCore).
2. **`exchange_fix`**: FIX 4.4 server implementation, session management, and binary converters.
3. **`exchange_matching`**: Pure C++ OrderBook and Matcher logic (Price-Time Priority).
4. **`exchange_persistence`**: Asynchronous SQLite persistence, repositories, and DB workers.
5. **`exchange_publishers`**: Market Data and Execution broadcast logic.
6. **`exchange_risk`**: Pre-trade risk checks and post-trade state updates.
7. **`exchange_routing`**: Command partitioning, Partition management, and dedicated worker threads.
8. **`exchange_state`**: Thread-safe ID Generators (OrderID, TradeID) and OrderManager.

Design Philosophy

• Lock-Free Command Path: Every Partition has its own dedicated thread and SPSCQueue, eliminating contention between symbols.
• Dependency Injection: Components are designed to be injected (e.g., TradingCore constructor), making the system highly testable with mocks.
• Zero-Copy Principles: Binary message converters avoid intermediate strings or allocations wherever possible.
• Asynchronous I/O: Database writes and networking events are handled on separate threads to keep the matching loop at microsecond latencies.

Building and Testing

You can build the entire exchange or target specific mini-libraries:

# Build the main server
cmake --build build --target fix -j$(nproc)
 
# Build all exchange tests
cmake --build build --target exchange_app_tests -j$(nproc)
 
# Run tests
ctest -R exchange_