WebSocket++, on_message event

我对这段代码有问题：

#include "stdafx.h"
#include <iostream>
#include <Windows.h>
#include <fstream>
#include <websocketpp/config/asio_no_tls_client.hpp>
#include <websocketpp/client.hpp>
#include <websocketpp/common/thread.hpp>
using namespace std;
class auth_client {
public:
    typedef websocketpp::client<websocketpp::config::asio_client> client;
    typedef websocketpp::lib::lock_guard<websocketpp::lib::mutex> scoped_lock;
    typedef websocketpp::config::asio_client::message_type::ptr message_ptr;
    typedef websocketpp::client<websocketpp::config::asio_client> client;
    auth_client() : m_open(false), m_done(false) {
        m_client.clear_access_channels(websocketpp::log::alevel::all);
        m_client.set_access_channels(websocketpp::log::alevel::connect);
        m_client.set_access_channels(websocketpp::log::alevel::disconnect);
        m_client.set_access_channels(websocketpp::log::alevel::app);
        m_client.init_asio();
        using websocketpp::lib::placeholders::_1;
        using websocketpp::lib::bind;
        m_client.set_open_handler(bind(&auth_client::on_open, this, ::_1));
        m_client.set_close_handler(bind(&auth_client::on_close, this, ::_1));
        m_client.set_fail_handler(bind(&auth_client::on_fail, this, ::_1));
        m_client.set_message_handler(bind(&auth_client::on_msg, this, ::_1));
    }
    void on_msg(websocketpp::connection_hdl hdl, message_ptr msg) {
        m_client.get_alog().write(websocketpp::log::alevel::app,
            "Connection opened, starting telemetry!");
        scoped_lock guard(m_lock);
        m_open = true;
    }
    void run(const std::string & uri) {
        websocketpp::lib::error_code ec;
        client::connection_ptr con = m_client.get_connection(uri, ec);
        if (ec) {
            m_client.get_alog().write(websocketpp::log::alevel::app,
                "Get Connection Error: " + ec.message());
            return;
        }
        m_hdl = con->get_handle();
        m_client.connect(con);
        websocketpp::lib::thread asio_thread(&client::run, &m_client);
        asio_thread.join();
    }
    void on_open(websocketpp::connection_hdl hdl) {
        scoped_lock guard(m_lock);
        m_open = true;
    }
    void on_close(websocketpp::connection_hdl hdl) {
        scoped_lock guard(m_lock);
        m_done = true;
    }
    void on_fail(websocketpp::connection_hdl hdl) {
        scoped_lock guard(m_lock);
        m_done = true;
    }
private:
    client m_client;
    websocketpp::connection_hdl m_hdl;
    websocketpp::lib::mutex m_lock;
    bool m_open;
    bool m_done;
};
int _tmain(int argc, _TCHAR* argv[])
{
    auth_client c;
    std::string uri = "ws://localhost:9002";
    c.run(uri);
    return 0;
}

只是不断收到此错误：错误图片

我只是CPP的初学者，不了解所有功能。首先它说好像它听不懂"message_ptr"但后来我补充说：

typedef websocketpp::config::asio_client::message_type::ptr message_ptr;

它仍然不起作用。如何解决？