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  26 <div class="titlepage"><div><div><h6 class="title">
  27 <a name="beast.ref.boost__beast__websocket__stream.async_accept.overload2"></a><a class="link" href="overload2.html" title="websocket::stream::async_accept (2 of 3 overloads)">websocket::stream::async_accept
  28           (2 of 3 overloads)</a>
  29 </h6></div></div></div>
  30 <p>
  31             Perform the WebSocket handshake asynchronously in the server role.
  32           </p>
  33 <h7><a name="beast.ref.boost__beast__websocket__stream.async_accept.overload2.h0"></a>
  34             <span class="phrase"><a name="beast.ref.boost__beast__websocket__stream.async_accept.overload2.synopsis"></a></span><a class="link" href="overload2.html#beast.ref.boost__beast__websocket__stream.async_accept.overload2.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 href="../../../../../../../../doc/html/boost_asio/reference/ConstBufferSequence.html" target="_top"><span class="emphasis"><em>ConstBufferSequence</em></span></a><span class="special">,</span>
  37     <span class="keyword">class</span> <span class="identifier">AcceptHandler</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;&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_accept</span><span class="special">(</span>
  40     <span class="identifier">ConstBufferSequence</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">buffers</span><span class="special">,</span>
  41     <span class="identifier">AcceptHandler</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>
  42 </pre>
  43 <h7><a name="beast.ref.boost__beast__websocket__stream.async_accept.overload2.h1"></a>
  44             <span class="phrase"><a name="beast.ref.boost__beast__websocket__stream.async_accept.overload2.description"></a></span><a class="link" href="overload2.html#beast.ref.boost__beast__websocket__stream.async_accept.overload2.description">Description</a>
  45           </h7><p>
  46             This initiating function is used to asynchronously begin performing the
  47             <a href="https://en.wikipedia.org/wiki/WebSocket#Protocol_handshake" target="_top">WebSocket
  48             handshake</a>, required before messages can be sent and received.
  49             During the handshake, the client sends the Websocket Upgrade HTTP request,
  50             and the server replies with an HTTP response indicating the result of
  51             the handshake. This call always returns immediately. The asynchronous
  52             operation will continue until one of the following conditions is true:
  53           </p>
  54 <div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
  55 <li class="listitem">
  56                 The request is received and the response is sent.
  57               </li>
  58 <li class="listitem">
  59                 An error occurs.
  60               </li>
  61 </ul></div>
  62 <p>
  63             The algorithm, known as a <span class="emphasis"><em>composed asynchronous operation</em></span>,
  64             is implemented in terms of calls to the next layer's <code class="computeroutput"><span class="identifier">async_read_some</span></code>
  65             and <code class="computeroutput"><span class="identifier">async_write_some</span></code>
  66             functions. No other operation may be performed on the stream until this
  67             operation completes. If a valid upgrade request is received, an HTTP
  68             response with a <a href="https://tools.ietf.org/html/rfc7230#section-3.1.2" target="_top">status-code</a>
  69             of <a class="link" href="../../boost__beast__http__status.html" title="http::status"><code class="computeroutput"><span class="identifier">http</span><span class="special">::</span><span class="identifier">switching_protocols</span></code></a> is sent
  70             to the peer, otherwise a non-successful error is associated with the
  71             operation. If the request size exceeds the capacity of the stream's internal
  72             buffer, 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">buffer_overflow</span></code></a> will be indicated.
  73             To handle larger requests, an application should read the HTTP request
  74             directly using <a class="link" href="../../boost__beast__http__async_read.html" title="http::async_read"><code class="computeroutput"><span class="identifier">http</span><span class="special">::</span><span class="identifier">async_read</span></code></a> and then pass the
  75             request to the appropriate overload of <a class="link" href="../accept.html" title="websocket::stream::accept"><code class="computeroutput"><span class="identifier">websocket</span><span class="special">::</span><span class="identifier">stream</span><span class="special">::</span><span class="identifier">accept</span></code></a> or <a class="link" href="../async_accept.html" title="websocket::stream::async_accept"><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_accept</span></code></a>
  76           </p>
  77 <h7><a name="beast.ref.boost__beast__websocket__stream.async_accept.overload2.h2"></a>
  78             <span class="phrase"><a name="beast.ref.boost__beast__websocket__stream.async_accept.overload2.parameters"></a></span><a class="link" href="overload2.html#beast.ref.boost__beast__websocket__stream.async_accept.overload2.parameters">Parameters</a>
  79           </h7><div class="informaltable"><table class="table">
  80 <colgroup>
  81 <col>
  82 <col>
  83 </colgroup>
  84 <thead><tr>
  85 <th>
  86                     <p>
  87                       Name
  88                     </p>
  89                   </th>
  90 <th>
  91                     <p>
  92                       Description
  93                     </p>
  94                   </th>
  95 </tr></thead>
  96 <tbody>
  97 <tr>
  98 <td>
  99                     <p>
 100                       <code class="computeroutput"><span class="identifier">buffers</span></code>
 101                     </p>
 102                   </td>
 103 <td>
 104                     <p>
 105                       Caller provided data that has already been received on the
 106                       stream. This may be used for implementations allowing multiple
 107                       protocols on the same stream. The buffered data will first
 108                       be applied to the handshake, and then to received WebSocket
 109                       frames. The implementation will copy the caller provided data
 110                       before the function returns.
 111                     </p>
 112                   </td>
 113 </tr>
 114 <tr>
 115 <td>
 116                     <p>
 117                       <code class="computeroutput"><span class="identifier">handler</span></code>
 118                     </p>
 119                   </td>
 120 <td>
 121                     <p>
 122                       The completion handler to invoke when the operation completes.
 123                       The implementation takes ownership of the handler by performing
 124                       a decay-copy. The equivalent function signature of the handler
 125                       must be:
 126                     </p>
 127 <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>
 128     <span class="identifier">error_code</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">ec</span>    <span class="comment">// Result of operation</span>
 129 <span class="special">);</span>
 130 </pre>
 131                     <p>
 132                       Regardless of whether the asynchronous operation completes
 133                       immediately or not, the handler will not be invoked from within
 134                       this function. Invocation of the handler will be performed
 135                       in a manner equivalent to using <code class="computeroutput"><span class="identifier">net</span><span class="special">::</span><span class="identifier">post</span></code>.
 136                     </p>
 137                   </td>
 138 </tr>
 139 </tbody>
 140 </table></div>
 141 <h7><a name="beast.ref.boost__beast__websocket__stream.async_accept.overload2.h3"></a>
 142             <span class="phrase"><a name="beast.ref.boost__beast__websocket__stream.async_accept.overload2.see_also"></a></span><a class="link" href="overload2.html#beast.ref.boost__beast__websocket__stream.async_accept.overload2.see_also">See
 143             Also</a>
 144           </h7><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">
 145                 <a href="https://tools.ietf.org/html/rfc6455#section-4.2" target="_top">Websocket
 146                 Opening Handshake Server Requirements (RFC6455)</a>
 147               </li></ul></div>
 148 </div>
 149 <table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
 150 <td align="left"></td>
 151 <td align="right"><div class="copyright-footer">Copyright &#169; 2016-2019 Vinnie
 152       Falco<p>
 153         Distributed under the Boost Software License, Version 1.0. (See accompanying
 154         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>)
 155       </p>
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