1<html> 2<head> 3<meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> 4<title>websocket::stream::async_accept (2 of 3 overloads)</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="../async_accept.html" title="websocket::stream::async_accept"> 9<link rel="prev" href="overload1.html" title="websocket::stream::async_accept (1 of 3 overloads)"> 10<link rel="next" href="overload3.html" title="websocket::stream::async_accept (3 of 3 overloads)"> 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="overload1.html"><img src="../../../../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../async_accept.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="overload3.html"><img src="../../../../../../../../doc/src/images/next.png" alt="Next"></a> 24</div> 25<div class="section"> 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"><</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"><</span><a class="link" href="../executor_type.html" title="websocket::stream::executor_type">executor_type</a><span class="special">>></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">&</span> <span class="identifier">buffers</span><span class="special">,</span> 41 <span class="identifier">AcceptHandler</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> 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">beast</span><span class="special">::</span><span class="identifier">http</span><span class="special">::</span><span class="identifier">status</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">error</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/overload1.html" title="http::async_read (1 of 2 overloads)"><code class="computeroutput"> 75 <span class="identifier">http</span><span class="special">::</span><span class="identifier">async_read</span> </code></a> and then pass the 76 request to the appropriate overload of <a class="link" href="../accept/overload1.html" title="websocket::stream::accept (1 of 6 overloads)"><code class="computeroutput"><span class="identifier">accept</span></code></a> or <a class="link" href="overload1.html" title="websocket::stream::async_accept (1 of 3 overloads)"><code class="computeroutput"><span class="identifier">async_accept</span></code></a> 77 </p> 78<h7><a name="beast.ref.boost__beast__websocket__stream.async_accept.overload2.h2"></a> 79 <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> 80 </h7><div class="informaltable"><table class="table"> 81<colgroup> 82<col> 83<col> 84</colgroup> 85<thead><tr> 86<th> 87 <p> 88 Name 89 </p> 90 </th> 91<th> 92 <p> 93 Description 94 </p> 95 </th> 96</tr></thead> 97<tbody> 98<tr> 99<td> 100 <p> 101 <code class="computeroutput"><span class="identifier">buffers</span></code> 102 </p> 103 </td> 104<td> 105 <p> 106 Caller provided data that has already been received on the 107 stream. This may be used for implementations allowing multiple 108 protocols on the same stream. The buffered data will first 109 be applied to the handshake, and then to received WebSocket 110 frames. The implementation will copy the caller provided data 111 before the function returns. 112 </p> 113 </td> 114</tr> 115<tr> 116<td> 117 <p> 118 <code class="computeroutput"><span class="identifier">handler</span></code> 119 </p> 120 </td> 121<td> 122 <p> 123 The completion handler to invoke when the operation completes. 124 The implementation takes ownership of the handler by performing 125 a decay-copy. The equivalent function signature of the handler 126 must be: 127 </p> 128<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> 129 <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> 130<span class="special">);</span> 131</pre> 132 <p> 133 Regardless of whether the asynchronous operation completes 134 immediately or not, the handler will not be invoked from within 135 this function. Invocation of the handler will be performed 136 in a manner equivalent to using <code class="computeroutput"><span class="identifier">net</span><span class="special">::</span><span class="identifier">post</span></code>. 137 </p> 138 </td> 139</tr> 140</tbody> 141</table></div> 142<h7><a name="beast.ref.boost__beast__websocket__stream.async_accept.overload2.h3"></a> 143 <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 144 Also</a> 145 </h7><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"> 146 <a href="https://tools.ietf.org/html/rfc6455#section-4.2" target="_top">Websocket 147 Opening Handshake Server Requirements (RFC6455)</a> 148 </li></ul></div> 149</div> 150<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> 151<td align="left"></td> 152<td align="right"><div class="copyright-footer">Copyright © 2016-2019 Vinnie 153 Falco<p> 154 Distributed under the Boost Software License, Version 1.0. (See accompanying 155 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>) 156 </p> 157</div></td> 158</tr></table> 159<hr> 160<div class="spirit-nav"> 161<a accesskey="p" href="overload1.html"><img src="../../../../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../async_accept.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="overload3.html"><img src="../../../../../../../../doc/src/images/next.png" alt="Next"></a> 162</div> 163</body> 164</html> 165
