<html> <head> <meta http-equiv="Content-Type" content="text/html; charset=US-ASCII"> <title>Daytime.2 - A synchronous TCP daytime server</title> <link rel="stylesheet" href="../../boostbook.css" type="text/css"> <meta name="generator" content="DocBook XSL Stylesheets V1.73.2"> <link rel="start" href="../../index.html" title="Asio"> <link rel="up" href="../tutorial.html" title="Tutorial"> <link rel="prev" href="tutdaytime1/src.html" title="Source listing for Daytime.1"> <link rel="next" href="tutdaytime2/src.html" title="Source listing for Daytime.2"> </head> <body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"> <table cellpadding="2" width="100%"><tr><td valign="top"><img alt="asio C++ library" width="250" height="60" src="../../asio.png"></td></tr></table> <hr> <div class="spirit-nav"> <a accesskey="p" href="tutdaytime1/src.html"><img src="../../prev.png" alt="Prev"></a><a accesskey="u" href="../tutorial.html"><img src="../../up.png" alt="Up"></a><a accesskey="h" href="../../index.html"><img src="../../home.png" alt="Home"></a><a accesskey="n" href="tutdaytime2/src.html"><img src="../../next.png" alt="Next"></a> </div> <div class="section" lang="en"> <div class="titlepage"><div><div><h3 class="title"> <a name="asio.tutorial.tutdaytime2"></a><a class="link" href="tutdaytime2.html" title="Daytime.2 - A synchronous TCP daytime server">Daytime.2 - A synchronous TCP daytime server</a> </h3></div></div></div> <p> This tutorial program shows how to use asio to implement a server application with TCP. </p> <pre class="programlisting"><span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">ctime</span><span class="special">></span> <span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">iostream</span><span class="special">></span> <span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">string</span><span class="special">></span> <span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">asio</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span> <span class="keyword">using</span> <span class="identifier">asio</span><span class="special">::</span><span class="identifier">ip</span><span class="special">::</span><span class="identifier">tcp</span><span class="special">;</span> </pre> <p> We define the function <code class="computeroutput"><span class="identifier">make_daytime_string</span><span class="special">()</span></code> to create the string to be sent back to the client. This function will be reused in all of our daytime server applications. </p> <pre class="programlisting"><span class="identifier">std</span><span class="special">::</span><span class="identifier">string</span> <span class="identifier">make_daytime_string</span><span class="special">()</span> <span class="special">{</span> <span class="keyword">using</span> <span class="keyword">namespace</span> <span class="identifier">std</span><span class="special">;</span> <span class="comment">// For time_t, time and ctime; </span> <span class="identifier">time_t</span> <span class="identifier">now</span> <span class="special">=</span> <span class="identifier">time</span><span class="special">(</span><span class="number">0</span><span class="special">);</span> <span class="keyword">return</span> <span class="identifier">ctime</span><span class="special">(&</span><span class="identifier">now</span><span class="special">);</span> <span class="special">}</span> <span class="keyword">int</span> <span class="identifier">main</span><span class="special">()</span> <span class="special">{</span> <span class="keyword">try</span> <span class="special">{</span> <span class="identifier">asio</span><span class="special">::</span><span class="identifier">io_service</span> <span class="identifier">io_service</span><span class="special">;</span> </pre> <p> A <a class="link" href="../reference/ip__tcp/acceptor.html" title="ip::tcp::acceptor">ip::tcp::acceptor</a> object needs to be created to listen for new connections. It is initialised to listen on TCP port 13, for IP version 4. </p> <pre class="programlisting"> <span class="identifier">tcp</span><span class="special">::</span><span class="identifier">acceptor</span> <span class="identifier">acceptor</span><span class="special">(</span><span class="identifier">io_service</span><span class="special">,</span> <span class="identifier">tcp</span><span class="special">::</span><span class="identifier">endpoint</span><span class="special">(</span><span class="identifier">tcp</span><span class="special">::</span><span class="identifier">v4</span><span class="special">(),</span> <span class="number">13</span><span class="special">));</span> </pre> <p> This is an iterative server, which means that it will handle one connection at a time. Create a socket that will represent the connection to the client, and then wait for a connection. </p> <pre class="programlisting"> <span class="keyword">for</span> <span class="special">(;;)</span> <span class="special">{</span> <span class="identifier">tcp</span><span class="special">::</span><span class="identifier">socket</span> <span class="identifier">socket</span><span class="special">(</span><span class="identifier">io_service</span><span class="special">);</span> <span class="identifier">acceptor</span><span class="special">.</span><span class="identifier">accept</span><span class="special">(</span><span class="identifier">socket</span><span class="special">);</span> </pre> <p> A client is accessing our service. Determine the current time and transfer this information to the client. </p> <pre class="programlisting"> <span class="identifier">std</span><span class="special">::</span><span class="identifier">string</span> <span class="identifier">message</span> <span class="special">=</span> <span class="identifier">make_daytime_string</span><span class="special">();</span> <span class="identifier">asio</span><span class="special">::</span><span class="identifier">error_code</span> <span class="identifier">ignored_error</span><span class="special">;</span> <span class="identifier">asio</span><span class="special">::</span><span class="identifier">write</span><span class="special">(</span><span class="identifier">socket</span><span class="special">,</span> <span class="identifier">asio</span><span class="special">::</span><span class="identifier">buffer</span><span class="special">(</span><span class="identifier">message</span><span class="special">),</span> <span class="identifier">asio</span><span class="special">::</span><span class="identifier">transfer_all</span><span class="special">(),</span> <span class="identifier">ignored_error</span><span class="special">);</span> <span class="special">}</span> <span class="special">}</span> </pre> <p> Finally, handle any exceptions. </p> <pre class="programlisting"> <span class="keyword">catch</span> <span class="special">(</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">exception</span><span class="special">&</span> <span class="identifier">e</span><span class="special">)</span> <span class="special">{</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">cerr</span> <span class="special"><<</span> <span class="identifier">e</span><span class="special">.</span><span class="identifier">what</span><span class="special">()</span> <span class="special"><<</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span><span class="special">;</span> <span class="special">}</span> <span class="keyword">return</span> <span class="number">0</span><span class="special">;</span> <span class="special">}</span> </pre> <p> See the <a class="link" href="tutdaytime2/src.html" title="Source listing for Daytime.2">full source listing</a> </p> <p> Return to the <a class="link" href="../tutorial.html" title="Tutorial">tutorial index</a> </p> <p> Previous: <a class="link" href="tutdaytime1.html" title="Daytime.1 - A synchronous TCP daytime client">Daytime.1 - A synchronous TCP daytime client</a> </p> <p> Next: <a class="link" href="tutdaytime3.html" title="Daytime.3 - An asynchronous TCP daytime server">Daytime.3 - An asynchronous TCP daytime server</a> </p> </div> <table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> <td align="left"></td> <td align="right"><div class="copyright-footer">Copyright © 2003 - 2010 Christopher M. Kohlhoff<p> Distributed under the Boost Software License, Version 1.0. (See accompanying 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>) </p> </div></td> </tr></table> <hr> <div class="spirit-nav"> <a accesskey="p" href="tutdaytime1/src.html"><img src="../../prev.png" alt="Prev"></a><a accesskey="u" href="../tutorial.html"><img src="../../up.png" alt="Up"></a><a accesskey="h" href="../../index.html"><img src="../../home.png" alt="Home"></a><a accesskey="n" href="tutdaytime2/src.html"><img src="../../next.png" alt="Next"></a> </div> </body> </html>