Hi I'm trying to create some code based on the code of the socket tutorial of the boost website. The code to create a UDP socket which will send datagram is the following one : boost::asio::io_service io_service; udp::resolver resolver(io_service); udp::resolver::query query(udp::v4(), argv[1], "daytime"); udp::endpoint receiver_endpoint = *resolver.resolve(query); udp::socket socket(io_service); socket.open(udp::v4()); But, to send something else than a Daytime request, I need to know what are the avalaible option to put instead of "daytime" in this line : udp::resolver::query query(udp::v4(), argv[1], "daytime"); Unfortunately and as far sa I know, the documentation is quite light about that. The only that I found is this one : http://www.boost.org/doc/libs/1_37_0/doc/html/boost_asio/reference/ip__basic... it is quite empty. Eventually, my goal is to use a specified port instead of a name of service. Thanks in advance for the help. Johan