Using WebSocket

The API uses a single persistent WebSocket connection. You connect, send one or multiple Protobuf‑encoded PlanRequest messages, and receive a stream of PlanResult responses.

Why WebSocket

WebSocket provides a stateful, low‑overhead channel ideal for:

• Progressive trip updates.
• Continuous monitoring of changing travel conditions.
• Strongly typed schemas, version‑safe.
• Avoiding repeated HTTP handshakes.

Each connection can handle multiple requests in sequence or parallel — perfect for user interfaces showing live travel options.

Why Protobuf:

Protocol Buffers offer:

• Compact binary format (smaller payloads).
• Strict typing — ensuring predictable decoding.
• Strongly typed schemas, version‑safe.
• Backwards compatibility for evolving schemas.

Example schema excerpt:

PlanRequest.proto

message PlanRequest {
    string fromPlace = 1;
    string toPlace = 2;
    string timestamp = 7;
    bool arriveBy = 8;
    UserPreferences userPreferences = 19;
}