Demo: TCP byte-stream 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_tcp_echo --parallel
./build/examples/sttnet_tcp_echo

3. Validation

printf "hello" | nc 127.0.0.1 9002

Expected: hello

4. Complete Source

#include <sttnet.h>

#include <iostream>

class EchoTcpServer final : public stt::network::TcpServer
{
protected:
    // TcpServer leaves heartbeat policy to derived protocols.
    // This byte-echo demo does not need application-level heartbeat.
    void handleHeartbeat() override {}
};

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

    if(!ServerSetting::blockTerminationSignals())
        return 1;

    EchoTcpServer server;

    // Raw TCP is a byte stream: one callback is one received chunk, not
    // necessarily one complete application message. Real protocols add
    // framing such as a fixed header, a length prefix, or a delimiter.
    server.setGlobalSolveFunction(
        [](TcpFDHandler &client, TcpInformation &info) {
            // In a server callback, sendData() submits bytes to the bounded
            // Reactor write queue; it does not block on the peer's network.
            return client.sendData(info.data) > 0;
        });

    if(!server.startListen(6060))
    {
        std::cerr << "failed to listen on port 6060\n";
        return 2;
    }

    std::cout << "TCP echo listening on 127.0.0.1:6060\n";
    ServerSetting::waitForTerminationSignal();
    return server.close() ? 0 : 3;
}