Demo: WebSocket echo

Buildable, runnable, verifiable, and synchronized with the repository source.

1. Example Scope

Key calls are explained with English comments, and the page includes run commands, validation steps, and adjustable settings.

2. Build and Run

cmake --build build --target sttnet_websocket_echo --parallel
./build/examples/sttnet_websocket_echo

3. Validation

Use a browser WebSocket client or websocat to connect to ws://127.0.0.1:5050/echo

Expected: The server echoes text and binary frames

4. Complete Source

#include <sttnet.h>

#include <iostream>
#include <string_view>

int main()
{
    using namespace stt::network;
    using namespace stt::data;
    using stt::system::ServerSetting;

    if(!ServerSetting::blockTerminationSignals())
    {
        std::cerr << "failed to block termination signals\n";
        return 1;
    }

    WebSocketServer server;

    // Check the HTTP upgrade request before accepting the WebSocket handshake.
    // This demo accepts only /echo and an optional query string.
    server.setJudgeFunction(
        [](WebSocketFDInformation &connection) {
            const bool correctPath =
                connection.locPara == "/echo" ||
                connection.locPara.rfind("/echo?", 0) == 0;

            // A real service may also inspect connection.header here, for
            // example with HttpStringUtil::get_value_header().
            return correctPath;
        });

    // The global callback receives messages that do not use a custom key route.
    // It returns bool: false tells STTNet that message handling failed.
    server.setGlobalSolveFunction(
        [](WebSocketServerFDHandler &client,
           WebSocketFDInformation &message) {
            // RFC 6455 opcode 1 is text and opcode 2 is binary.
            const std::string frameType =
                message.message_type == 2 ? "0010" : "0001";

            // Echo the payload using the same text/binary frame type.
            return client.sendMessage(message.message, frameType);
        });

    // Close idle connections and require a heartbeat response within 30 seconds.
    server.setTimeOutTime(20);   // Idle timeout in minutes.
    server.setHBTimeOutTime(30); // Heartbeat response timeout in seconds.

    if(!server.startListen(5050))
    {
        std::cerr << "failed to listen on port 5050\n";
        return 2;
    }

    std::cout << "WebSocket echo listening on ws://127.0.0.1:5050/echo\n";
    ServerSetting::waitForTerminationSignal();
    return server.close() ? 0 : 3;
}