===== WebSocket API Introduction =====

The WebSocket API provides a high-performance, low-latency communication channel for real-time trading data and order execution. This section introduces the key technologies used in the API: **WebSockets** and **Google Protocol Buffers (Protobuf)**.

==== WebSockets ====
WebSockets establish a persistent, full-duplex connection between the client and server, allowing for continuous bi-directional message exchange. This ensures minimal latency, making it ideal for market data feeds and order updates.

**Key Advantages:**
  * Persistent connection reduces handshake overhead
  * Low-latency, real-time data exchange
  * Efficient bandwidth usage compared to REST APIs

==== Google Protocol Buffers (Protobuf) ====
The API utilizes Protobuf for efficient, compact, and high-speed message serialization. Unlike JSON or XML, Protobuf messages are smaller and faster to parse, making them well-suited for high-frequency trading applications.

**Why Protobuf?**
  * **Compact Encoding:** Reduces message size for faster transmission
  * **High Performance:** Faster serialization/deserialization than JSON
  * **Schema Evolution:** Backward-compatible changes allow for future expansion without breaking existing clients

==== Communication Model ====
The API follows a structured messaging approach:
  * **Client Messages:** Requests sent from clients to the server (e.g., order submission, subscription requests)
  * **Server Messages:** Responses and real-time updates sent from the server (e.g., trade confirmations, market data)

==== Message Structure Overview ====
All messages are wrapped within a top-level client or server message envelope. This structure ensures extensibility and consistency across different message types.

**Example Envelope:**
```
message ClientMessage {
  oneof payload {
    SubscribeRequest subscribe = 1;
    OrderRequest order = 2;
  }
}

message ServerMessage {
  oneof payload {
    MarketUpdate market_data = 1;
    OrderResponse order_response = 2;
  }
}
```

This design enables efficient message parsing while maintaining flexibility.

==== Next Steps ====
Continue to the **[Connecting and Authenticating](developers:websocket:connecting)** section to learn how to establish a WebSocket connection and authenticate your session.