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 #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 (); // methods virtual 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(port)); boost::system::error_code ec; tcp::resolver::iterator iter = resolver.resolve(query, ec); tcp::resolver::iterator end; // pick the first endpoint if (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; }