boost的网络库asio

boost在1.35版本之后终于加入了网络库asio。春节期间终于得闲能够一窥究竟，同时将boost.asio和知名的ACE框架做一下比较。

 

asio的名字突出了异步I/O的能力，从asio的文档中看到它使用了和ACE Proactor框架中相似的Proactor模式。CSDN上也有很多网友也写了很多关于异步I/O的好文章，但是我还是决定从同步I/O开始。尽管阻塞I/O不是那么酷那么绚丽但是在网络编程中它和异步I/O一样重要。

 

下面是一个简单的同步I/O的例子，使用的是锁步(lock-step)方式的通讯。

 

 

#include <string>#include "boost/asio.hpp"#include "boost/lexical_cast.hpp"using namespace std;using namespace boost;using boost::asio::ip::tcp;using boost::asio::io_service;class Client{public:Client (const string & hostname, unsigned short port);virtual ~Client ();// methodsvirtual void send (const string & message);virtual string recv ();virtual void close ();private:io_service * io_service_;tcp::socket * socket_;};Client::Client (const string & hostname, unsigned short port){io_service_ = new io_service();socket_ = new tcp::socket(*io_service_);tcp::resolver resolver(*io_service_);tcp::resolver::query query(hostname, boost::lexical_cast<string, unsigned short>(port));boost::system::error_code ec;tcp::resolver::iterator iter = resolver.resolve(query, ec);tcp::resolver::iterator end;// pick the first endpointif (iter != end && ec == 0){tcp::endpoint endpoint = *iter;std::cout << "Connecting to: " << endpoint << std::endl;socket_->connect(endpoint, ec);if (ec){std::cerr << "Error: " << ec << std::endl;throw ec;}}}Client::~Client (){delete socket_;delete io_service_;}void Client::send (const string & message){boost::asio::const_buffers_1 request(message.data(), message.size());socket_->send(request);}string Client::recv (){char response[128];size_t num = socket_->receive(boost::asio::buffer(response));if (num > 0){return string (response, num);}return "";}void Client::close (){socket_->close();}int _tmain(int argc, _TCHAR* argv[]){Client client ("localhost", 2009);std::cout << client.recv() << endl;string request;do{std::cout << "Request: ";std::cin >> request;if (request == "q")break;client.send (request);std::cout << "Response: " << client.recv() << endl;}while (true);client.close();return 0;}