128 lines
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128 lines
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<title>Daytime.2 - A synchronous TCP daytime server</title>
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<div class="titlepage"><div><div><h3 class="title">
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<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
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TCP daytime server</a>
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</h3></div></div></div>
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<p>
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This tutorial program shows how to use asio to implement a server application
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with TCP.
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</p>
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<pre class="programlisting">#include <ctime>
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#include <iostream>
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#include <string>
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#include <boost/asio.hpp>
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using boost::asio::ip::tcp;
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</pre>
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<p>
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We define the function <code class="computeroutput">make_daytime_string()</code> to create the string
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to be sent back to the client. This function will be reused in all of our
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daytime server applications.
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</p>
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<pre class="programlisting">std::string make_daytime_string()
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{
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using namespace std; // For time_t, time and ctime;
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time_t now = time(0);
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return ctime(&now);
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}
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int main()
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{
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try
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{
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boost::asio::io_context io_context;
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</pre>
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<p>
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A <a class="link" href="../reference/ip__tcp/acceptor.html" title="ip::tcp::acceptor">ip::tcp::acceptor</a>
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object needs to be created to listen for new connections. It is initialised
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to listen on TCP port 13, for IP version 4.
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</p>
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<pre class="programlisting"> tcp::acceptor acceptor(io_context, tcp::endpoint(tcp::v4(), 13));
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</pre>
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<p>
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This is an iterative server, which means that it will handle one connection
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at a time. Create a socket that will represent the connection to the client,
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and then wait for a connection.
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</p>
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<pre class="programlisting"> for (;;)
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{
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tcp::socket socket(io_context);
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acceptor.accept(socket);
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</pre>
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<p>
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A client is accessing our service. Determine the current time and transfer
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this information to the client.
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</p>
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<pre class="programlisting"> std::string message = make_daytime_string();
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boost::system::error_code ignored_error;
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boost::asio::write(socket, boost::asio::buffer(message), ignored_error);
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}
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}
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</pre>
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<p>
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Finally, handle any exceptions.
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</p>
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<pre class="programlisting"> catch (std::exception& e)
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{
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std::cerr << e.what() << std::endl;
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}
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return 0;
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}
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</pre>
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<p>
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See the <a class="link" href="tutdaytime2/src.html" title="Source listing for Daytime.2">full source listing</a>
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</p>
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<p>
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Return to the <a class="link" href="../tutorial.html" title="Tutorial">tutorial index</a>
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</p>
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<p>
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Previous: <a class="link" href="tutdaytime1.html" title="Daytime.1 - A synchronous TCP daytime client">Daytime.1 - A synchronous
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TCP daytime client</a>
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</p>
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<p>
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Next: <a class="link" href="tutdaytime3.html" title="Daytime.3 - An asynchronous TCP daytime server">Daytime.3 - An asynchronous
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TCP daytime server</a>
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</p>
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<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
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<td align="left"></td>
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<td align="right"><div class="copyright-footer">Copyright © 2003-2021 Christopher
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M. Kohlhoff<p>
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Distributed under the Boost Software License, Version 1.0. (See accompanying
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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>)
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