unity c# client:

private void Start()
{
    var socketManager = new SocketManager(new System.Uri(string.Format("{0}:{1}", "127.0.0.1", "6000")));
    socket = socketManager.Socket;

    socket.On<ConnectResponse> (SocketIOEventTypes.Connect, OnConnected); //连接 
    socket.On(SocketIOEventTypes.Disconnect, OnDisconnected);
    socket.On<Socket,Dictionary<string, string>>("GameMessage", OnReadMessage);
    socket.On<Dictionary<string, string>>("start", ConnectedMessage);
}

private void ConnectedMessage(Dictionary<string, string> msg)
{
    Debug.Log("第一次 Connected! :");
    foreach (var item in msg)
    {
        Debug.Log("接收发送回来的start "+ item);
    }

    //发送一个可以回调的消息 ExpectAcknowledgement
    socket.ExpectAcknowledgement<Dictionary<string, string>>((dict) =>
    {
        foreach (var item in dict)
        {
            Debug.Log("回调: " + item);
        }
    }).Emit("message", msg);
}
// 接收消息 并且反馈给server
private void OnReadMessage(Socket socket, Dictionary<string, string> msg)
{
    Dictionary<string, string> keyValues = msg;
    foreach (var item in keyValues)
    {
        Debug.LogWarning("收到服务器消息:" + item);
    }

    Dictionary<string, string> data = new Dictionary<string, string>();
    data.Add("clientmsg", "谢谢你Server!");
    socket.EmitAck(data);
}

node Server:

    let express = Express();
    const httpServer: any = HTTP.createServer(express);
    const IO = new Server(httpServer, { pingTimeout: 9999999, pingInterval: 999999 });

    IO.on('connection', (socket: any) => {
        console.log(socket.id);
        socket.emit("start", {msg: 'ok!'});

        socket.on("message", (data:any, callback:Function)=>{
            console.log("接收消息: " , data);
            if(callback) callback({back:'回调参数!'});
        });

        socket.emit("GameMessage", { msg: '你好!'}, (ref:any)=>{
            console.log("返回客户端回调: ", ref);
        });
    });

    httpServer.listen(6000, () => {
        if (httpServer != null) {
            const port = httpServer.address().port
            let str = 'start socket.io server! listening on *:' + port;
            console.log(str);
        }
    });