using namespace boost::network::http; // parameters are in this namespace
handler handler_instance;
async_server<handler>::options options(handler_instance);
options.address("0.0.0.0")
       .port("80")
       .io_service(boost::make_shared<boost::asio::io_service>())
       .thread_pool(boost::make_shared<boost::network::utils::thread_pool>(2))
       .reuse_address(true);
async_server<handler> instance(options);
instance.run();