text: //
  // sender.cpp
  // ~~~~~~~~~~
  //
  // Copyright (c) 2003-2012 Christopher M. Kohlhoff (chris at kohlhoff dot com)
  //
  // Distributed under the Boost Software License, Version 1.0. (See accompanying
  // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
  //
  
  #include <iostream>
  #include <sstream>
  #include <string>
  #include <boost/asio.hpp>
  #include "boost/bind.hpp"
  #include "boost/date_time/posix_time/posix_time_types.hpp"
  
  const short multicast_port = 30001;
  const int max_message_count = 10;
  
  class sender
  {
  public:
    sender(boost::asio::io_service& io_service,
        const boost::asio::ip::address& multicast_address)
      : endpoint_(multicast_address, multicast_port),
        socket_(io_service, endpoint_.protocol()),
        timer_(io_service),
        message_count_(0)
    {
      std::ostringstream os;
      os << "Message " << message_count_++;
      message_ = os.str();
  
      socket_.async_send_to(
          boost::asio::buffer(message_), endpoint_,
          boost::bind(&sender::handle_send_to, this,
            boost::asio::placeholders::error));
    }
  
    void handle_send_to(const boost::system::error_code& error)
    {
      if (!error && message_count_ < max_message_count)
      {
        timer_.expires_from_now(boost::posix_time::seconds(1));
        timer_.async_wait(
            boost::bind(&sender::handle_timeout, this,
              boost::asio::placeholders::error));
      }
    }
  
    void handle_timeout(const boost::system::error_code& error)
    {
      if (!error)
      {
        std::ostringstream os;
        os << "Message " << message_count_++;
        message_ = os.str();
  
        socket_.async_send_to(
            boost::asio::buffer(message_), endpoint_,
            boost::bind(&sender::handle_send_to, this,
              boost::asio::placeholders::error));
      }
    }
  
  private:
    boost::asio::ip::udp::endpoint endpoint_;
    boost::asio::ip::udp::socket socket_;
    boost::asio::deadline_timer timer_;
    int message_count_;
    std::string message_;
  };
  
  int main(int argc, char* argv[])
  {
    try
    {
      if (argc != 2)
      {
        std::cerr << "Usage: sender <multicast_address>\n";
        std::cerr << "  For IPv4, try:\n";
        std::cerr << "    sender 239.255.0.1\n";
        std::cerr << "  For IPv6, try:\n";
        std::cerr << "    sender ff31::8000:1234\n";
        return 1;
      }
  
      boost::asio::io_service io_service;
      sender s(io_service, boost::asio::ip::address::from_string(argv[1]));
      io_service.run();
    }
    catch (std::exception& e)
    {
      std::cerr << "Exception: " << e.what() << "\n";
    }
  
    return 0;
  }
  