...one of the most highly
regarded and expertly designed C++ library projects in the
world.
— Herb Sutter and Andrei
Alexandrescu, C++
Coding Standards
This tutorial program shows how to combine the two asynchronous servers that we have just written, into a single server application.
int main() { try { boost::asio::io_context io_context;
We will begin by creating a server object to accept a TCP client connection.
tcp_server server1(io_context);
We also need a server object to accept a UDP client request.
udp_server server2(io_context);
We have created two lots of work for the io_context object to do.
io_context.run(); } catch (std::exception& e) { std::cerr << e.what() << std::endl; } return 0; }
The following two classes are taken from Daytime.3.
class tcp_connection : public std::enable_shared_from_this<tcp_connection> { public: typedef std::shared_ptr<tcp_connection> pointer; static pointer create(boost::asio::io_context& io_context) { return pointer(new tcp_connection(io_context)); } tcp::socket& socket() { return socket_; } void start() { message_ = make_daytime_string(); boost::asio::async_write(socket_, boost::asio::buffer(message_), std::bind(&tcp_connection::handle_write, shared_from_this())); } private: tcp_connection(boost::asio::io_context& io_context) : socket_(io_context) { } void handle_write() { } tcp::socket socket_; std::string message_; }; class tcp_server { public: tcp_server(boost::asio::io_context& io_context) : io_context_(io_context), acceptor_(io_context, tcp::endpoint(tcp::v4(), 13)) { start_accept(); } private: void start_accept() { tcp_connection::pointer new_connection = tcp_connection::create(io_context_); acceptor_.async_accept(new_connection->socket(), std::bind(&tcp_server::handle_accept, this, new_connection, boost::asio::placeholders::error)); } void handle_accept(tcp_connection::pointer new_connection, const boost::system::error_code& error) { if (!error) { new_connection->start(); } start_accept(); } boost::asio::io_context& io_context_; tcp::acceptor acceptor_; };
Similarly, this next class is taken from the previous tutorial step.
class udp_server { public: udp_server(boost::asio::io_context& io_context) : socket_(io_context, udp::endpoint(udp::v4(), 13)) { start_receive(); } private: void start_receive() { socket_.async_receive_from( boost::asio::buffer(recv_buffer_), remote_endpoint_, std::bind(&udp_server::handle_receive, this, boost::asio::placeholders::error)); } void handle_receive(const boost::system::error_code& error) { if (!error) { std::shared_ptr<std::string> message( new std::string(make_daytime_string())); socket_.async_send_to(boost::asio::buffer(*message), remote_endpoint_, std::bind(&udp_server::handle_send, this, message)); start_receive(); } } void handle_send(std::shared_ptr<std::string> /*message*/) { } udp::socket socket_; udp::endpoint remote_endpoint_; std::array<char, 1> recv_buffer_; };
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