libs/beast/doc/html/beast/ref/boost__beast__websocket__stream/async_ping.html

   1 <html>
   2 <head>
   3 <meta http-equiv="Content-Type" content="text/html; charset=US-ASCII">
   4 <title>websocket::stream::async_ping</title>
   5 <link rel="stylesheet" href="../../../../../../../doc/src/boostbook.css" type="text/css">
   6 <meta name="generator" content="DocBook XSL Stylesheets V1.79.1">
   7 <link rel="home" href="../../../index.html" title="Chapter&#160;1.&#160;Boost.Beast">
   8 <link rel="up" href="../boost__beast__websocket__stream.html" title="websocket::stream">
   9 <link rel="prev" href="async_handshake/overload2.html" title="websocket::stream::async_handshake (2 of 2 overloads)">
  10 <link rel="next" href="async_pong.html" title="websocket::stream::async_pong">
  11 </head>
  12 <body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF">
  13 <table cellpadding="2" width="100%"><tr>
  14 <td valign="top"><img alt="Boost C++ Libraries" width="277" height="86" src="../../../../../../../boost.png"></td>
  15 <td align="center"><a href="../../../../../../../index.html">Home</a></td>
  16 <td align="center"><a href="../../../../../../../libs/libraries.htm">Libraries</a></td>
  17 <td align="center"><a href="http://www.boost.org/users/people.html">People</a></td>
  18 <td align="center"><a href="http://www.boost.org/users/faq.html">FAQ</a></td>
  19 <td align="center"><a href="../../../../../../../more/index.htm">More</a></td>
  20 </tr></table>
  21 <hr>
  22 <div class="spirit-nav">
  23 <a accesskey="p" href="async_handshake/overload2.html"><img src="../../../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../boost__beast__websocket__stream.html"><img src="../../../../../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../../../index.html"><img src="../../../../../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="async_pong.html"><img src="../../../../../../../doc/src/images/next.png" alt="Next"></a>
  24 </div>
  25 <div class="section">
  26 <div class="titlepage"><div><div><h5 class="title">
  27 <a name="beast.ref.boost__beast__websocket__stream.async_ping"></a><a class="link" href="async_ping.html" title="websocket::stream::async_ping">websocket::stream::async_ping</a>
  28 </h5></div></div></div>
  29 <p>
  30           <a class="indexterm" name="idm45873472952176"></a>
  31 Send a websocket ping control frame asynchronously.
  32         </p>
  33 <h6>
  34 <a name="beast.ref.boost__beast__websocket__stream.async_ping.h0"></a>
  35           <span class="phrase"><a name="beast.ref.boost__beast__websocket__stream.async_ping.synopsis"></a></span><a class="link" href="async_ping.html#beast.ref.boost__beast__websocket__stream.async_ping.synopsis">Synopsis</a>
  36         </h6>
  37 <pre class="programlisting"><span class="keyword">template</span><span class="special">&lt;</span>
  38     <span class="keyword">class</span> <a href="../../../../../../../doc/html/boost_asio/reference/WriteHandler.html" target="_top"><span class="emphasis"><em>WriteHandler</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>
  39 <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>
  40 <span class="identifier">async_ping</span><span class="special">(</span>
  41     <span class="identifier">ping_data</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">payload</span><span class="special">,</span>
  42     <span class="identifier">WriteHandler</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 <h6>
  45 <a name="beast.ref.boost__beast__websocket__stream.async_ping.h1"></a>
  46           <span class="phrase"><a name="beast.ref.boost__beast__websocket__stream.async_ping.description"></a></span><a class="link" href="async_ping.html#beast.ref.boost__beast__websocket__stream.async_ping.description">Description</a>
  47         </h6>
  48 <p>
  49           This function is used to asynchronously send a <a href="https://tools.ietf.org/html/rfc6455#section-5.5.2" target="_top">ping
  50           frame</a>, which usually elicits an automatic pong control frame response
  51           from the peer.
  52         </p>
  53 <div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
  54 <li class="listitem">
  55               The ping frame is written.
  56             </li>
  57 <li class="listitem">
  58               An error occurs.
  59             </li>
  60 </ul></div>
  61 <p>
  62           The algorithm, known as a <span class="emphasis"><em>composed asynchronous operation</em></span>,
  63           is implemented in terms of calls to the next layer's <code class="computeroutput"><span class="identifier">async_write_some</span></code>
  64           function. The program must ensure that no other calls to <a class="link" href="ping.html" title="websocket::stream::ping"><code class="computeroutput"><span class="identifier">websocket</span><span class="special">::</span><span class="identifier">stream</span><span class="special">::</span><span class="identifier">ping</span></code></a>, <a class="link" href="pong.html" title="websocket::stream::pong"><code class="computeroutput"><span class="identifier">websocket</span><span class="special">::</span><span class="identifier">stream</span><span class="special">::</span><span class="identifier">pong</span></code></a>, <a class="link" href="async_ping.html" title="websocket::stream::async_ping"><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_ping</span></code></a>, or <a class="link" href="async_pong.html" title="websocket::stream::async_pong"><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_pong</span></code></a> are performed until
  65           this operation completes. If a close frame is sent or received before the
  66           ping frame is sent, the error received by this completion handler will
  67           be <code class="computeroutput"><span class="identifier">net</span><span class="special">::</span><span class="identifier">error</span><span class="special">::</span><span class="identifier">operation_aborted</span></code>.
  68         </p>
  69 <h6>
  70 <a name="beast.ref.boost__beast__websocket__stream.async_ping.h2"></a>
  71           <span class="phrase"><a name="beast.ref.boost__beast__websocket__stream.async_ping.parameters"></a></span><a class="link" href="async_ping.html#beast.ref.boost__beast__websocket__stream.async_ping.parameters">Parameters</a>
  72         </h6>
  73 <div class="informaltable"><table class="table">
  74 <colgroup>
  75 <col>
  76 <col>
  77 </colgroup>
  78 <thead><tr>
  79 <th>
  80                   <p>
  81                     Name
  82                   </p>
  83                 </th>
  84 <th>
  85                   <p>
  86                     Description
  87                   </p>
  88                 </th>
  89 </tr></thead>
  90 <tbody>
  91 <tr>
  92 <td>
  93                   <p>
  94                     <code class="computeroutput"><span class="identifier">payload</span></code>
  95                   </p>
  96                 </td>
  97 <td>
  98                   <p>
  99                     The payload of the ping message, which may be empty. The implementation
 100                     will not access the contents of this object after the initiating
 101                     function returns.
 102                   </p>
 103                 </td>
 104 </tr>
 105 <tr>
 106 <td>
 107                   <p>
 108                     <code class="computeroutput"><span class="identifier">handler</span></code>
 109                   </p>
 110                 </td>
 111 <td>
 112                   <p>
 113                     The completion handler to invoke when the operation completes.
 114                     The implementation takes ownership of the handler by performing
 115                     a decay-copy. The equivalent function signature of the handler
 116                     must be:
 117                   </p>
 118 <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>
 119     <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>
 120 <span class="special">);</span>
 121 </pre>
 122                   <p>
 123                     Regardless of whether the asynchronous operation completes immediately
 124                     or not, the handler will not be invoked from within this function.
 125                     Invocation of the handler will be performed in a manner equivalent
 126                     to using <code class="computeroutput"><span class="identifier">net</span><span class="special">::</span><span class="identifier">post</span></code>.
 127                   </p>
 128                 </td>
 129 </tr>
 130 </tbody>
 131 </table></div>
 132 </div>
 133 <table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
 134 <td align="left"></td>
 135 <td align="right"><div class="copyright-footer">Copyright &#169; 2016-2019 Vinnie
 136       Falco<p>
 137         Distributed under the Boost Software License, Version 1.0. (See accompanying
 138         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>)
 139       </p>
 140 </div></td>
 141 </tr></table>
 142 <hr>
 143 <div class="spirit-nav">
 144 <a accesskey="p" href="async_handshake/overload2.html"><img src="../../../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../boost__beast__websocket__stream.html"><img src="../../../../../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../../../index.html"><img src="../../../../../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="async_pong.html"><img src="../../../../../../../doc/src/images/next.png" alt="Next"></a>
 145 </div>
 146 </body>
 147 </html>