[asio-users] question regarding design

[Goran]

Hi all,

I wanna change the design of some async client (code at end of this
message) towards something like "run as a server and pull a message
from another server".

The so called "another server" will be my master server in future. At
the moment I'm taking some example from asio's documentation:
http://www.boost.org/doc/libs/1_46_1/doc/html/boost_asio/tutorial/tutdaytime3.html

The async client is derived from another example of asio's documentation:
http://www.boost.org/doc/libs/1_46_1/doc/html/boost_asio/example/http/client/async_client.cpp

My simple question is: How would you change the code below to run in a
loop and pulls 'let's say' every second a message from master server?

Thanks a lot!


#include <iostream>
#include <istream>
#include <ostream>
#include <string>
#include <boost/asio.hpp>
#include <boost/bind.hpp>

using boost::asio::ip::tcp;

class client
{
public:
client(boost::asio::io_service& io_service,
const std::string& server, const std::string& port)
: resolver_(io_service),
socket_(io_service)
{
// Start an asynchronous resolve to translate the server and service names
// into a list of endpoints.
tcp::resolver::query query(server, port);
resolver_.async_resolve(query,
boost::bind(&client::handle_resolve, this,
boost::asio::placeholders::error,
boost::asio::placeholders::iterator));
}

private:
void handle_resolve(const boost::system::error_code& err,
tcp::resolver::iterator endpoint_iterator)
{
if (!err)
{
// Attempt a connection to each endpoint in the list until we
// successfully establish a connection.
tcp::endpoint endpoint = *endpoint_iterator;
socket_.async_connect(endpoint,
boost::bind(&client::handle_connect, this,
boost::asio::placeholders::error));
}
else
{
std::cout << "Error: " << err.message() << "\n";
}
}

void handle_connect(const boost::system::error_code& err)
{
if (!err)
{
// The connection was successful. Read the response.
boost::asio::async_read(socket_, response_,
boost::bind(&client::handle_response, this));
}
else if (err != boost::asio::error::eof)
{
std::cout << "Error: " << err.message() << "\n";
}
}

void handle_response()
{
if (response_.size() > 0)
std::cout << "Response: " << &response_;
else
std::cout << "Response is empty." << std::endl;
}

tcp::resolver resolver_;
tcp::socket socket_;
boost::asio::streambuf request_;
boost::asio::streambuf response_;
};

int main(int argc, char* argv[])
{
try
{
if (argc != 3)
{
std::cout << "Usage: async_client <server> <port>\n";
std::cout << "Example:\n";
std::cout << " async_client localhost 2020\n";
return 1;
}

boost::asio::io_service io_service;
client c(io_service, argv[1], argv[2]);
io_service.run();
}
catch (std::exception& e)
{
std::cout << "Exception: " << e.what() << "\n";
}

return 0;
}