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  26 <div class="titlepage"><div><div><h6 class="title">
  27 <a name="beast.ref.boost__beast__websocket__stream.async_read_some.overload1"></a><a class="link" href="overload1.html" title="websocket::stream::async_read_some (1 of 2 overloads)">websocket::stream::async_read_some
  28           (1 of 2 overloads)</a>
  29 </h6></div></div></div>
  30 <p>
  31             Read some message data asynchronously.
  32           </p>
  33 <h7><a name="beast.ref.boost__beast__websocket__stream.async_read_some.overload1.h0"></a>
  34             <span class="phrase"><a name="beast.ref.boost__beast__websocket__stream.async_read_some.overload1.synopsis"></a></span><a class="link" href="overload1.html#beast.ref.boost__beast__websocket__stream.async_read_some.overload1.synopsis">Synopsis</a>
  35           </h7><pre class="programlisting"><span class="keyword">template</span><span class="special">&lt;</span>
  36     <span class="keyword">class</span> <a class="link" href="../../../concepts/DynamicBuffer.html" title="DynamicBuffer"><span class="emphasis"><em>DynamicBuffer</em></span></a><span class="special">,</span>
  37     <span class="keyword">class</span> <a href="../../../../../../../../doc/html/boost_asio/reference/ReadHandler.html" target="_top"><span class="emphasis"><em>ReadHandler</em></span></a> <span class="special">=</span> <span class="identifier">net</span><span class="special">::</span><span class="identifier">default_completion_token_t</span><span class="special">&lt;</span>                <span class="identifier">executor_type</span><span class="special">&gt;&gt;</span>
  38 <a href="../../../../../../../../doc/html/boost_asio/reference/asynchronous_operations.html#boost_asio.reference.asynchronous_operations.automatic_deduction_of_initiating_function_return_type" target="_top"><span class="emphasis"><em>DEDUCED</em></span></a>
  39 <span class="identifier">async_read_some</span><span class="special">(</span>
  40     <span class="identifier">DynamicBuffer</span><span class="special">&amp;</span> <span class="identifier">buffer</span><span class="special">,</span>
  41     <span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span> <span class="identifier">limit</span><span class="special">,</span>
  42     <span class="identifier">ReadHandler</span><span class="special">&amp;&amp;</span> <span class="identifier">handler</span> <span class="special">=</span> <span class="identifier">net</span><span class="special">::</span><span class="identifier">default_completion_token_t</span><span class="special">&lt;</span> <span class="identifier">executor_type</span> <span class="special">&gt;{});</span>
  43 </pre>
  44 <h7><a name="beast.ref.boost__beast__websocket__stream.async_read_some.overload1.h1"></a>
  45             <span class="phrase"><a name="beast.ref.boost__beast__websocket__stream.async_read_some.overload1.description"></a></span><a class="link" href="overload1.html#beast.ref.boost__beast__websocket__stream.async_read_some.overload1.description">Description</a>
  46           </h7><p>
  47             This function is used to asynchronously read some message data. This
  48             call always returns immediately. The asynchronous operation will continue
  49             until one of the following conditions is true:
  50           </p>
  51 <div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
  52 <li class="listitem">
  53                 Some message data is received.
  54               </li>
  55 <li class="listitem">
  56                 A close frame is received. In this case the error indicated by the
  57                 function will be <a class="link" href="../../boost__beast__websocket__error.html" title="websocket::error"><code class="computeroutput"><span class="identifier">websocket</span><span class="special">::</span><span class="identifier">closed</span></code></a>.
  58               </li>
  59 <li class="listitem">
  60                 An error occurs.
  61               </li>
  62 </ul></div>
  63 <p>
  64             The algorithm, known as a <span class="emphasis"><em>composed asynchronous operation</em></span>,
  65             is implemented in terms of calls to the next layer's <code class="computeroutput"><span class="identifier">async_read_some</span></code>
  66             and <code class="computeroutput"><span class="identifier">async_write_some</span></code>
  67             functions. The program must ensure that no other calls to <a class="link" href="../read.html" title="websocket::stream::read"><code class="computeroutput"><span class="identifier">websocket</span><span class="special">::</span><span class="identifier">stream</span><span class="special">::</span><span class="identifier">read</span></code></a>, <a class="link" href="../read_some.html" title="websocket::stream::read_some"><code class="computeroutput"><span class="identifier">websocket</span><span class="special">::</span><span class="identifier">stream</span><span class="special">::</span><span class="identifier">read_some</span></code></a>, <a class="link" href="../async_read.html" title="websocket::stream::async_read"><code class="computeroutput"><span class="identifier">websocket</span><span class="special">::</span><span class="identifier">stream</span><span class="special">::</span><span class="identifier">async_read</span></code></a>, or <a class="link" href="../async_read_some.html" title="websocket::stream::async_read_some"><code class="computeroutput"><span class="identifier">websocket</span><span class="special">::</span><span class="identifier">stream</span><span class="special">::</span><span class="identifier">async_read_some</span></code></a> are performed
  68             until this operation completes. Received message data is appended to
  69             the buffer. The functions <a class="link" href="../got_binary.html" title="websocket::stream::got_binary"><code class="computeroutput"><span class="identifier">websocket</span><span class="special">::</span><span class="identifier">stream</span><span class="special">::</span><span class="identifier">got_binary</span></code></a> and <a class="link" href="../got_text.html" title="websocket::stream::got_text"><code class="computeroutput"><span class="identifier">websocket</span><span class="special">::</span><span class="identifier">stream</span><span class="special">::</span><span class="identifier">got_text</span></code></a> may be used to query
  70             the stream and determine the type of the last received message. Until
  71             the operation completes, the implementation will read incoming control
  72             frames and handle them automatically as follows:
  73           </p>
  74 <div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
  75 <li class="listitem">
  76                 The <a class="link" href="../control_callback.html" title="websocket::stream::control_callback"><code class="computeroutput"><span class="identifier">websocket</span><span class="special">::</span><span class="identifier">stream</span><span class="special">::</span><span class="identifier">control_callback</span></code></a> will be
  77                 invoked for each control frame.
  78               </li>
  79 <li class="listitem">
  80                 For each received ping frame, a pong frame will be automatically
  81                 sent.
  82               </li>
  83 <li class="listitem">
  84                 If a close frame is received, the WebSocket close procedure is performed.
  85                 In this case, when the function returns, the error <a class="link" href="../../boost__beast__websocket__error.html" title="websocket::error"><code class="computeroutput"><span class="identifier">websocket</span><span class="special">::</span><span class="identifier">closed</span></code></a> will be indicated.
  86               </li>
  87 </ul></div>
  88 <p>
  89             Pong frames and close frames sent by the implementation while the read
  90             operation is outstanding do not prevent the application from also writing
  91             message data, sending pings, sending pongs, or sending close frames.
  92           </p>
  93 <h7><a name="beast.ref.boost__beast__websocket__stream.async_read_some.overload1.h2"></a>
  94             <span class="phrase"><a name="beast.ref.boost__beast__websocket__stream.async_read_some.overload1.parameters"></a></span><a class="link" href="overload1.html#beast.ref.boost__beast__websocket__stream.async_read_some.overload1.parameters">Parameters</a>
  95           </h7><div class="informaltable"><table class="table">
  96 <colgroup>
  97 <col>
  98 <col>
  99 </colgroup>
 100 <thead><tr>
 101 <th>
 102                     <p>
 103                       Name
 104                     </p>
 105                   </th>
 106 <th>
 107                     <p>
 108                       Description
 109                     </p>
 110                   </th>
 111 </tr></thead>
 112 <tbody>
 113 <tr>
 114 <td>
 115                     <p>
 116                       <code class="computeroutput"><span class="identifier">buffer</span></code>
 117                     </p>
 118                   </td>
 119 <td>
 120                     <p>
 121                       A dynamic buffer to append message data to.
 122                     </p>
 123                   </td>
 124 </tr>
 125 <tr>
 126 <td>
 127                     <p>
 128                       <code class="computeroutput"><span class="identifier">limit</span></code>
 129                     </p>
 130                   </td>
 131 <td>
 132                     <p>
 133                       An upper limit on the number of bytes this function will append
 134                       into the buffer. If this value is zero, then a reasonable size
 135                       will be chosen automatically.
 136                     </p>
 137                   </td>
 138 </tr>
 139 <tr>
 140 <td>
 141                     <p>
 142                       <code class="computeroutput"><span class="identifier">handler</span></code>
 143                     </p>
 144                   </td>
 145 <td>
 146                     <p>
 147                       The completion handler to invoke when the operation completes.
 148                       The implementation takes ownership of the handler by performing
 149                       a decay-copy. The equivalent function signature of the handler
 150                       must be:
 151                     </p>
 152 <pre xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="table-programlisting"><span class="keyword">void</span> <span class="identifier">handler</span><span class="special">(</span>
 153     <span class="identifier">error_code</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">ec</span><span class="special">,</span>       <span class="comment">// Result of operation</span>
 154     <span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span> <span class="identifier">bytes_written</span>   <span class="comment">// Number of bytes appended to buffer</span>
 155 <span class="special">);</span>
 156 </pre>
 157                     <p>
 158                       Regardless of whether the asynchronous operation completes
 159                       immediately or not, the handler will not be invoked from within
 160                       this function. Invocation of the handler will be performed
 161                       in a manner equivalent to using <code class="computeroutput"><span class="identifier">net</span><span class="special">::</span><span class="identifier">post</span></code>.
 162                     </p>
 163                   </td>
 164 </tr>
 165 </tbody>
 166 </table></div>
 167 </div>
 168 <table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
 169 <td align="left"></td>
 170 <td align="right"><div class="copyright-footer">Copyright &#169; 2016-2019 Vinnie
 171       Falco<p>
 172         Distributed under the Boost Software License, Version 1.0. (See accompanying
 173         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>)
 174       </p>
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