1<html> 2<head> 3<meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> 4<title>Daytime.5 - A synchronous UDP daytime server</title> 5<link rel="stylesheet" href="../../../../doc/src/boostbook.css" type="text/css"> 6<meta name="generator" content="DocBook XSL Stylesheets V1.79.1"> 7<link rel="home" href="../../boost_asio.html" title="Boost.Asio"> 8<link rel="up" href="../tutorial.html" title="Tutorial"> 9<link rel="prev" href="tutdaytime4/src.html" title="Source listing for Daytime.4"> 10<link rel="next" href="tutdaytime5/src.html" title="Source listing for Daytime.5"> 11</head> 12<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"> 13<table cellpadding="2" width="100%"><tr> 14<td valign="top"><img alt="Boost C++ Libraries" width="277" height="86" src="../../../../boost.png"></td> 15<td align="center"><a href="../../../../index.html">Home</a></td> 16<td align="center"><a href="../../../../libs/libraries.htm">Libraries</a></td> 17<td align="center"><a href="http://www.boost.org/users/people.html">People</a></td> 18<td align="center"><a href="http://www.boost.org/users/faq.html">FAQ</a></td> 19<td align="center"><a href="../../../../more/index.htm">More</a></td> 20</tr></table> 21<hr> 22<div class="spirit-nav"> 23<a accesskey="p" href="tutdaytime4/src.html"><img src="../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../tutorial.html"><img src="../../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../../boost_asio.html"><img src="../../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="tutdaytime5/src.html"><img src="../../../../doc/src/images/next.png" alt="Next"></a> 24</div> 25<div class="section"> 26<div class="titlepage"><div><div><h3 class="title"> 27<a name="boost_asio.tutorial.tutdaytime5"></a><a class="link" href="tutdaytime5.html" title="Daytime.5 - A synchronous UDP daytime server">Daytime.5 - A synchronous 28 UDP daytime server</a> 29</h3></div></div></div> 30<p> 31 This tutorial program shows how to use asio to implement a server application 32 with UDP. 33 </p> 34<pre class="programlisting">int main() 35{ 36 try 37 { 38 boost::asio::io_context io_context; 39</pre> 40<p> 41 Create an <a class="link" href="../reference/ip__udp/socket.html" title="ip::udp::socket">ip::udp::socket</a> 42 object to receive requests on UDP port 13. 43 </p> 44<pre class="programlisting"> udp::socket socket(io_context, udp::endpoint(udp::v4(), 13)); 45</pre> 46<p> 47 Wait for a client to initiate contact with us. The remote_endpoint object 48 will be populated by <a class="link" href="../reference/basic_datagram_socket/receive_from.html" title="basic_datagram_socket::receive_from">ip::udp::socket::receive_from()</a>. 49 </p> 50<pre class="programlisting"> for (;;) 51 { 52 boost::array<char, 1> recv_buf; 53 udp::endpoint remote_endpoint; 54 socket.receive_from(boost::asio::buffer(recv_buf), remote_endpoint); 55</pre> 56<p> 57 Determine what we are going to send back to the client. 58 </p> 59<pre class="programlisting"> std::string message = make_daytime_string(); 60</pre> 61<p> 62 Send the response to the remote_endpoint. 63 </p> 64<pre class="programlisting"> boost::system::error_code ignored_error; 65 socket.send_to(boost::asio::buffer(message), 66 remote_endpoint, 0, ignored_error); 67 } 68 } 69</pre> 70<p> 71 Finally, handle any exceptions. 72 </p> 73<pre class="programlisting"> catch (std::exception& e) 74 { 75 std::cerr << e.what() << std::endl; 76 } 77 78 return 0; 79} 80</pre> 81<p> 82 See the <a class="link" href="tutdaytime5/src.html" title="Source listing for Daytime.5">full source listing</a> 83 </p> 84<p> 85 Return to the <a class="link" href="../tutorial.html" title="Tutorial">tutorial index</a> 86 </p> 87<p> 88 Previous: <a class="link" href="tutdaytime4.html" title="Daytime.4 - A synchronous UDP daytime client">Daytime.4 - A synchronous 89 UDP daytime client</a> 90 </p> 91<p> 92 Next: <a class="link" href="tutdaytime6.html" title="Daytime.6 - An asynchronous UDP daytime server">Daytime.6 - An asynchronous 93 UDP daytime server</a> 94 </p> 95</div> 96<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> 97<td align="left"></td> 98<td align="right"><div class="copyright-footer">Copyright © 2003-2020 Christopher M. 99 Kohlhoff<p> 100 Distributed under the Boost Software License, Version 1.0. (See accompanying 101 file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>) 102 </p> 103</div></td> 104</tr></table> 105<hr> 106<div class="spirit-nav"> 107<a accesskey="p" href="tutdaytime4/src.html"><img src="../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../tutorial.html"><img src="../../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../../boost_asio.html"><img src="../../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="tutdaytime5/src.html"><img src="../../../../doc/src/images/next.png" alt="Next"></a> 108</div> 109</body> 110</html> 111
