I'm converting some code from the previous asio release to the latest 0.37 and I am confused by the new resolver interface. ip::tcp::resolver resolver(io_service); ip::tcp::resolver::query query("foobar.com", "http"); ip::tcp::resolver::iterator iter = resolver.resolve(query); ip::tcp::resolver::iterator end; while (iter != end) { ip::tcp::endpoint ep = *iter; std::cout << iter->endpoint() << std::endl; std::cout << iter->host_name() << std::endl; std::cout << iter->service_name() << std::endl; ++iter; } The resolver::query requires a service name string. I want to specify a port number so that the endpoints returned by the resolver::iterator are configured with that specified port rather than those returned by the service name. It isn't clear to me, but it looks like it should be possible by passing numeric_service in the query flags, but on Windows AI_NUMERICSERV isn't defined and numeric_service == 0. Plus that leaks the rather ugly getaddrinfo() interface of using numeric strings. It would be nice if the interface allowed: ip::tcp::resolver::query query("foobar.com", 80); I feel like I might be missing something here. Thanks, Chris