title: how to resolve ftp site using boost.asio?
body: <p>Boost.asio documentation doesn't support any ftp examples.</p>
  
  <pre><code> `boost::asio::io_service io_service;
  tcp::resolver resolver(io_service);
  tcp::resolver::query query("www.boost.org", "http");
  tcp::resolver::iterator endpoint_iterator = resolver.resolve(query);`
  </code></pre>
  
  <p>that resolve http site and get an HTTP endpoint.</p>
  
  <p>but <code>tcp::resolver::query query("ftp://ftp.remotesensing.org/gdal/", "ftp");</code></p>
  
  <p>that result a Host not found ERROR. So how to resolve a ftp site.</p>