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  25 <div class="section">
  26 <div class="titlepage"><div><div><h4 class="title">
  27 <a name="boost_asio.overview.networking.iostreams"></a><a class="link" href="iostreams.html" title="Socket Iostreams">Socket Iostreams</a>
  28 </h4></div></div></div>
  29 <p>
  30           Boost.Asio includes classes that implement iostreams on top of sockets.
  31           These hide away the complexities associated with endpoint resolution, protocol
  32           independence, etc. To create a connection one might simply write:
  33         </p>
  34 <pre class="programlisting"><span class="identifier">ip</span><span class="special">::</span><span class="identifier">tcp</span><span class="special">::</span><span class="identifier">iostream</span> <span class="identifier">stream</span><span class="special">(</span><span class="string">"www.boost.org"</span><span class="special">,</span> <span class="string">"http"</span><span class="special">);</span>
  35 <span class="keyword">if</span> <span class="special">(!</span><span class="identifier">stream</span><span class="special">)</span>
  36 <span class="special">{</span>
  37   <span class="comment">// Can't connect.</span>
  38 <span class="special">}</span>
  39 </pre>
  40 <p>
  41           The iostream class can also be used in conjunction with an acceptor to
  42           create simple servers. For example:
  43         </p>
  44 <pre class="programlisting"><span class="identifier">io_service</span> <span class="identifier">ios</span><span class="special">;</span>
  45
  46 <span class="identifier">ip</span><span class="special">::</span><span class="identifier">tcp</span><span class="special">::</span><span class="identifier">endpoint</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">80</span><span class="special">);</span>
  47 <span class="identifier">ip</span><span class="special">::</span><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">ios</span><span class="special">,</span> <span class="identifier">endpoint</span><span class="special">);</span>
  48
  49 <span class="keyword">for</span> <span class="special">(;;)</span>
  50 <span class="special">{</span>
  51   <span class="identifier">ip</span><span class="special">::</span><span class="identifier">tcp</span><span class="special">::</span><span class="identifier">iostream</span> <span class="identifier">stream</span><span class="special">;</span>
  52   <span class="identifier">acceptor</span><span class="special">.</span><span class="identifier">accept</span><span class="special">(*</span><span class="identifier">stream</span><span class="special">.</span><span class="identifier">rdbuf</span><span class="special">());</span>
  53   <span class="special">...</span>
  54 <span class="special">}</span>
  55 </pre>
  56 <p>
  57           Timeouts may be set by calling <code class="computeroutput"><span class="identifier">expires_at</span><span class="special">()</span></code> or <code class="computeroutput"><span class="identifier">expires_from_now</span><span class="special">()</span></code> to establish a deadline. Any socket operations
  58           that occur past the deadline will put the iostream into a "bad"
  59           state.
  60         </p>
  61 <p>
  62           For example, a simple client program like this:
  63         </p>
  64 <pre class="programlisting"><span class="identifier">ip</span><span class="special">::</span><span class="identifier">tcp</span><span class="special">::</span><span class="identifier">iostream</span> <span class="identifier">stream</span><span class="special">;</span>
  65 <span class="identifier">stream</span><span class="special">.</span><span class="identifier">expires_from_now</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">posix_time</span><span class="special">::</span><span class="identifier">seconds</span><span class="special">(</span><span class="number">60</span><span class="special">));</span>
  66 <span class="identifier">stream</span><span class="special">.</span><span class="identifier">connect</span><span class="special">(</span><span class="string">"www.boost.org"</span><span class="special">,</span> <span class="string">"http"</span><span class="special">);</span>
  67 <span class="identifier">stream</span> <span class="special">&lt;&lt;</span> <span class="string">"GET /LICENSE_1_0.txt HTTP/1.0\r\n"</span><span class="special">;</span>
  68 <span class="identifier">stream</span> <span class="special">&lt;&lt;</span> <span class="string">"Host: www.boost.org\r\n"</span><span class="special">;</span>
  69 <span class="identifier">stream</span> <span class="special">&lt;&lt;</span> <span class="string">"Accept: */*\r\n"</span><span class="special">;</span>
  70 <span class="identifier">stream</span> <span class="special">&lt;&lt;</span> <span class="string">"Connection: close\r\n\r\n"</span><span class="special">;</span>
  71 <span class="identifier">stream</span><span class="special">.</span><span class="identifier">flush</span><span class="special">();</span>
  72 <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special">&lt;&lt;</span> <span class="identifier">stream</span><span class="special">.</span><span class="identifier">rdbuf</span><span class="special">();</span>
  73 </pre>
  74 <p>
  75           will fail if all the socket operations combined take longer than 60 seconds.
  76         </p>
  77 <p>
  78           If an error does occur, the iostream's <code class="computeroutput"><span class="identifier">error</span><span class="special">()</span></code> member function may be used to retrieve
  79           the error code from the most recent system call:
  80         </p>
  81 <pre class="programlisting"><span class="keyword">if</span> <span class="special">(!</span><span class="identifier">stream</span><span class="special">)</span>
  82 <span class="special">{</span>
  83   <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special">&lt;&lt;</span> <span class="string">"Error: "</span> <span class="special">&lt;&lt;</span> <span class="identifier">stream</span><span class="special">.</span><span class="identifier">error</span><span class="special">().</span><span class="identifier">message</span><span class="special">()</span> <span class="special">&lt;&lt;</span> <span class="string">"\n"</span><span class="special">;</span>
  84 <span class="special">}</span>
  85 </pre>
  86 <h6>
  87 <a name="boost_asio.overview.networking.iostreams.h0"></a>
  88           <span class="phrase"><a name="boost_asio.overview.networking.iostreams.see_also"></a></span><a class="link" href="iostreams.html#boost_asio.overview.networking.iostreams.see_also">See
  89           Also</a>
  90         </h6>
  91 <p>
  92           <a class="link" href="../../reference/ip__tcp/iostream.html" title="ip::tcp::iostream">ip::tcp::iostream</a>,
  93           <a class="link" href="../../reference/basic_socket_iostream.html" title="basic_socket_iostream">basic_socket_iostream</a>,
  94           <a class="link" href="../../examples/cpp03_examples.html#boost_asio.examples.cpp03_examples.iostreams">iostreams
  95           examples</a>.
  96         </p>
  97 <h6>
  98 <a name="boost_asio.overview.networking.iostreams.h1"></a>
  99           <span class="phrase"><a name="boost_asio.overview.networking.iostreams.notes"></a></span><a class="link" href="iostreams.html#boost_asio.overview.networking.iostreams.notes">Notes</a>
 100         </h6>
 101 <p>
 102           These iostream templates only support <code class="computeroutput"><span class="keyword">char</span></code>,
 103           not <code class="computeroutput"><span class="keyword">wchar_t</span></code>, and do not perform
 104           any code conversion.
 105         </p>
 106 </div>
 107 <table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
 108 <td align="left"></td>
 109 <td align="right"><div class="copyright-footer">Copyright &#169; 2003-2014 Christopher M. Kohlhoff<p>
 110         Distributed under the Boost Software License, Version 1.0. (See accompanying
 111         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>)
 112       </p>
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