1<html> 2<head> 3<meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> 4<title>Daytime.2 - A synchronous TCP 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="tutdaytime1/src.html" title="Source listing for Daytime.1"> 10<link rel="next" href="tutdaytime2/src.html" title="Source listing for Daytime.2"> 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="tutdaytime1/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="tutdaytime2/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.tutdaytime2"></a><a class="link" href="tutdaytime2.html" title="Daytime.2 - A synchronous TCP daytime server">Daytime.2 - A synchronous 28 TCP 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 TCP. 33 </p> 34<pre class="programlisting">#include <ctime> 35#include <iostream> 36#include <string> 37#include <boost/asio.hpp> 38 39using boost::asio::ip::tcp; 40</pre> 41<p> 42 We define the function <code class="computeroutput">make_daytime_string()</code> to create the string 43 to be sent back to the client. This function will be reused in all of our 44 daytime server applications. 45 </p> 46<pre class="programlisting">std::string make_daytime_string() 47{ 48 using namespace std; // For time_t, time and ctime; 49 time_t now = time(0); 50 return ctime(&now); 51} 52 53int main() 54{ 55 try 56 { 57 boost::asio::io_context io_context; 58</pre> 59<p> 60 A <a class="link" href="../reference/ip__tcp/acceptor.html" title="ip::tcp::acceptor">ip::tcp::acceptor</a> 61 object needs to be created to listen for new connections. It is initialised 62 to listen on TCP port 13, for IP version 4. 63 </p> 64<pre class="programlisting"> tcp::acceptor acceptor(io_context, tcp::endpoint(tcp::v4(), 13)); 65</pre> 66<p> 67 This is an iterative server, which means that it will handle one connection 68 at a time. Create a socket that will represent the connection to the client, 69 and then wait for a connection. 70 </p> 71<pre class="programlisting"> for (;;) 72 { 73 tcp::socket socket(io_context); 74 acceptor.accept(socket); 75</pre> 76<p> 77 A client is accessing our service. Determine the current time and transfer 78 this information to the client. 79 </p> 80<pre class="programlisting"> std::string message = make_daytime_string(); 81 82 boost::system::error_code ignored_error; 83 boost::asio::write(socket, boost::asio::buffer(message), ignored_error); 84 } 85 } 86</pre> 87<p> 88 Finally, handle any exceptions. 89 </p> 90<pre class="programlisting"> catch (std::exception& e) 91 { 92 std::cerr << e.what() << std::endl; 93 } 94 95 return 0; 96} 97</pre> 98<p> 99 See the <a class="link" href="tutdaytime2/src.html" title="Source listing for Daytime.2">full source listing</a> 100 </p> 101<p> 102 Return to the <a class="link" href="../tutorial.html" title="Tutorial">tutorial index</a> 103 </p> 104<p> 105 Previous: <a class="link" href="tutdaytime1.html" title="Daytime.1 - A synchronous TCP daytime client">Daytime.1 - A synchronous 106 TCP daytime client</a> 107 </p> 108<p> 109 Next: <a class="link" href="tutdaytime3.html" title="Daytime.3 - An asynchronous TCP daytime server">Daytime.3 - An asynchronous 110 TCP daytime server</a> 111 </p> 112</div> 113<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> 114<td align="left"></td> 115<td align="right"><div class="copyright-footer">Copyright © 2003-2020 Christopher M. 116 Kohlhoff<p> 117 Distributed under the Boost Software License, Version 1.0. (See accompanying 118 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>) 119 </p> 120</div></td> 121</tr></table> 122<hr> 123<div class="spirit-nav"> 124<a accesskey="p" href="tutdaytime1/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="tutdaytime2/src.html"><img src="../../../../doc/src/images/next.png" alt="Next"></a> 125</div> 126</body> 127</html> 128
