1<html> 2<head> 3<meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> 4<title>websocket::stream::async_pong</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 1. Boost.Beast"> 8<link rel="up" href="../boost__beast__websocket__stream.html" title="websocket::stream"> 9<link rel="prev" href="pong/overload2.html" title="websocket::stream::pong (2 of 2 overloads)"> 10<link rel="next" href="read.html" title="websocket::stream::read"> 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="pong/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="read.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_pong"></a><a class="link" href="async_pong.html" title="websocket::stream::async_pong">websocket::stream::async_pong</a> 28</h5></div></div></div> 29<p> 30 <a class="indexterm" name="idm46057518528224"></a> 31 </p> 32<p> 33 Send a websocket pong control frame asynchronously. 34 </p> 35<h6> 36<a name="beast.ref.boost__beast__websocket__stream.async_pong.h0"></a> 37 <span class="phrase"><a name="beast.ref.boost__beast__websocket__stream.async_pong.synopsis"></a></span><a class="link" href="async_pong.html#beast.ref.boost__beast__websocket__stream.async_pong.synopsis">Synopsis</a> 38 </h6> 39<pre class="programlisting"><span class="keyword">template</span><span class="special"><</span> 40 <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"><</span><a class="link" href="executor_type.html" title="websocket::stream::executor_type">executor_type</a><span class="special">>></span> 41<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> 42<span class="identifier">async_pong</span><span class="special">(</span> 43 <span class="identifier">ping_data</span> <span class="keyword">const</span><span class="special">&</span> <span class="identifier">payload</span><span class="special">,</span> 44 <span class="identifier">WriteHandler</span><span class="special">&&</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"><</span> <a class="link" href="executor_type.html" title="websocket::stream::executor_type">executor_type</a> <span class="special">>{});</span> 45</pre> 46<h6> 47<a name="beast.ref.boost__beast__websocket__stream.async_pong.h1"></a> 48 <span class="phrase"><a name="beast.ref.boost__beast__websocket__stream.async_pong.description"></a></span><a class="link" href="async_pong.html#beast.ref.boost__beast__websocket__stream.async_pong.description">Description</a> 49 </h6> 50<p> 51 This function is used to asynchronously send a <a href="https://tools.ietf.org/html/rfc6455#section-5.5.3" target="_top">pong 52 frame</a>, which is usually sent automatically in response to a ping 53 frame from the remote peer. 54 </p> 55<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "> 56<li class="listitem"> 57 The pong frame is written. 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_write_some</span></code> 66 function. The program must ensure that no other calls to <a class="link" href="ping/overload1.html" title="websocket::stream::ping (1 of 2 overloads)"><code class="computeroutput"><span class="identifier">ping</span></code></a>, <a class="link" href="pong/overload1.html" title="websocket::stream::pong (1 of 2 overloads)"><code class="computeroutput"><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">async_ping</span></code></a>, or <a class="link" href="async_pong.html" title="websocket::stream::async_pong"><code class="computeroutput"><span class="identifier">async_pong</span></code></a> are performed until 67 this operation completes. If a close frame is sent or received before the 68 pong frame is sent, the error received by this completion handler will 69 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>. WebSocket allows pong 70 frames to be sent at any time, without first receiving a ping. An unsolicited 71 pong sent in this fashion may indicate to the remote peer that the connection 72 is still active. 73 </p> 74<h6> 75<a name="beast.ref.boost__beast__websocket__stream.async_pong.h2"></a> 76 <span class="phrase"><a name="beast.ref.boost__beast__websocket__stream.async_pong.parameters"></a></span><a class="link" href="async_pong.html#beast.ref.boost__beast__websocket__stream.async_pong.parameters">Parameters</a> 77 </h6> 78<div class="informaltable"><table class="table"> 79<colgroup> 80<col> 81<col> 82</colgroup> 83<thead><tr> 84<th> 85 <p> 86 Name 87 </p> 88 </th> 89<th> 90 <p> 91 Description 92 </p> 93 </th> 94</tr></thead> 95<tbody> 96<tr> 97<td> 98 <p> 99 <code class="computeroutput"><span class="identifier">payload</span></code> 100 </p> 101 </td> 102<td> 103 <p> 104 The payload of the pong message, which may be empty. The implementation 105 will not access the contents of this object after the initiating 106 function returns. 107 </p> 108 </td> 109</tr> 110<tr> 111<td> 112 <p> 113 <code class="computeroutput"><span class="identifier">handler</span></code> 114 </p> 115 </td> 116<td> 117 <p> 118 The completion handler to invoke when the operation completes. 119 The implementation takes ownership of the handler by performing 120 a decay-copy. The equivalent function signature of the handler 121 must be: 122 </p> 123<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> 124 <span class="identifier">error_code</span> <span class="keyword">const</span><span class="special">&</span> <span class="identifier">ec</span> <span class="comment">// Result of operation</span> 125<span class="special">);</span> 126</pre> 127 <p> 128 Regardless of whether the asynchronous operation completes immediately 129 or not, the handler will not be invoked from within this function. 130 Invocation of the handler will be performed in a manner equivalent 131 to using <code class="computeroutput"><span class="identifier">net</span><span class="special">::</span><span class="identifier">post</span></code>. 132 </p> 133 </td> 134</tr> 135</tbody> 136</table></div> 137</div> 138<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> 139<td align="left"></td> 140<td align="right"><div class="copyright-footer">Copyright © 2016-2019 Vinnie 141 Falco<p> 142 Distributed under the Boost Software License, Version 1.0. (See accompanying 143 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>) 144 </p> 145</div></td> 146</tr></table> 147<hr> 148<div class="spirit-nav"> 149<a accesskey="p" href="pong/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="read.html"><img src="../../../../../../../doc/src/images/next.png" alt="Next"></a> 150</div> 151</body> 152</html> 153
