1<html> 2<head> 3<meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> 4<title>websocket::stream::async_handshake (2 of 2 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. 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This call always returns immediately. The asynchronous 53 operation will continue until one of the following conditions is true: 54 </p> 55<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "> 56<li class="listitem"> 57 The request is sent and the response is received. 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. No other operation may be performed on the stream until this 68 operation completes. The handshake is successful if the received HTTP 69 response indicates the upgrade was accepted by the server, represented 70 by a <a href="https://tools.ietf.org/html/rfc7230#section-3.1.2" target="_top">status-code</a> 71 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>. 72 </p> 73<h7><a name="beast.ref.boost__beast__websocket__stream.async_handshake.overload2.h2"></a> 74 <span class="phrase"><a name="beast.ref.boost__beast__websocket__stream.async_handshake.overload2.parameters"></a></span><a class="link" href="overload2.html#beast.ref.boost__beast__websocket__stream.async_handshake.overload2.parameters">Parameters</a> 75 </h7><div class="informaltable"><table class="table"> 76<colgroup> 77<col> 78<col> 79</colgroup> 80<thead><tr> 81<th> 82 <p> 83 Name 84 </p> 85 </th> 86<th> 87 <p> 88 Description 89 </p> 90 </th> 91</tr></thead> 92<tbody> 93<tr> 94<td> 95 <p> 96 <code class="computeroutput"><span class="identifier">res</span></code> 97 </p> 98 </td> 99<td> 100 <p> 101 The HTTP Upgrade response returned by the remote endpoint. 102 The caller may use the response to access any additional information 103 sent by the server. This object will be assigned before the 104 completion handler is invoked. 105 </p> 106 </td> 107</tr> 108<tr> 109<td> 110 <p> 111 <code class="computeroutput"><span class="identifier">host</span></code> 112 </p> 113 </td> 114<td> 115 <p> 116 The name of the remote host. This is required by the HTTP protocol 117 to set the "Host" header field. The implementation 118 will not access the string data after the initiating function 119 returns. 120 </p> 121 </td> 122</tr> 123<tr> 124<td> 125 <p> 126 <code class="computeroutput"><span class="identifier">target</span></code> 127 </p> 128 </td> 129<td> 130 <p> 131 The request-target, in origin-form. The server may use the 132 target to distinguish different services on the same listening 133 port. The implementation will not access the string data after 134 the initiating function returns. 135 </p> 136 </td> 137</tr> 138<tr> 139<td> 140 <p> 141 <code class="computeroutput"><span class="identifier">handler</span></code> 142 </p> 143 </td> 144<td> 145 <p> 146 The completion handler to invoke when the operation completes. 147 The implementation takes ownership of the handler by performing 148 a decay-copy. The equivalent function signature of the handler 149 must be: 150 </p> 151<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> 152 <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> 153<span class="special">);</span> 154</pre> 155 <p> 156 Regardless of whether the asynchronous operation completes 157 immediately or not, the handler will not be invoked from within 158 this function. Invocation of the handler will be performed 159 in a manner equivalent to using <code class="computeroutput"><span class="identifier">net</span><span class="special">::</span><span class="identifier">post</span></code>. 160 </p> 161 </td> 162</tr> 163</tbody> 164</table></div> 165<h7><a name="beast.ref.boost__beast__websocket__stream.async_handshake.overload2.h3"></a> 166 <span class="phrase"><a name="beast.ref.boost__beast__websocket__stream.async_handshake.overload2.example"></a></span><a class="link" href="overload2.html#beast.ref.boost__beast__websocket__stream.async_handshake.overload2.example">Example</a> 167 </h7><pre class="programlisting"><span class="identifier">response_type</span> <span class="identifier">res</span><span class="special">;</span> 168<span class="identifier">ws</span><span class="special">.</span><span class="identifier">async_handshake</span><span class="special">(</span><span class="identifier">res</span><span class="special">,</span> <span class="string">"localhost"</span><span class="special">,</span> <span class="string">"/"</span><span class="special">,</span> 169 <span class="special">[&</span><span class="identifier">res</span><span class="special">](</span><span class="identifier">error_code</span> <span class="identifier">ec</span><span class="special">)</span> 170 <span class="special">{</span> 171 <span class="keyword">if</span><span class="special">(</span><span class="identifier">ec</span><span class="special">)</span> 172 <span class="identifier">std</span><span class="special">::</span><span class="identifier">cerr</span> <span class="special"><<</span> <span class="string">"Error: "</span> <span class="special"><<</span> <span class="identifier">ec</span><span class="special">.</span><span class="identifier">message</span><span class="special">()</span> <span class="special"><<</span> <span class="string">"\n"</span><span class="special">;</span> 173 <span class="keyword">else</span> 174 <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special"><<</span> <span class="identifier">res</span><span class="special">;</span> 175 176 <span class="special">});</span> 177</pre> 178<h7><a name="beast.ref.boost__beast__websocket__stream.async_handshake.overload2.h4"></a> 179 <span class="phrase"><a name="beast.ref.boost__beast__websocket__stream.async_handshake.overload2.see_also"></a></span><a class="link" href="overload2.html#beast.ref.boost__beast__websocket__stream.async_handshake.overload2.see_also">See 180 Also</a> 181 </h7><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "> 182<li class="listitem"> 183 <a href="https://tools.ietf.org/html/rfc6455#section-4.1" target="_top">Websocket 184 Opening Handshake Client Requirements (RFC6455)</a> 185 </li> 186<li class="listitem"> 187 <a href="https://tools.ietf.org/html/rfc7230#section-5.4" target="_top">Host 188 field (RFC7230)</a> 189 </li> 190<li class="listitem"> 191 <a href="https://tools.ietf.org/html/rfc7230#section-3.1.1" target="_top">request-target 192 (RFC7230)</a> 193 </li> 194<li class="listitem"> 195 <a href="https://tools.ietf.org/html/rfc7230#section-5.3.1" target="_top">origin-form 196 (RFC7230)</a> 197 </li> 198</ul></div> 199</div> 200<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> 201<td align="left"></td> 202<td align="right"><div class="copyright-footer">Copyright © 2016-2019 Vinnie 203 Falco<p> 204 Distributed under the Boost Software License, Version 1.0. (See accompanying 205 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>) 206 </p> 207</div></td> 208</tr></table> 209<hr> 210<div class="spirit-nav"> 211<a accesskey="p" href="overload1.html"><img src="../../../../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../async_handshake.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="../accept.html"><img src="../../../../../../../../doc/src/images/next.png" alt="Next"></a> 212</div> 213</body> 214</html> 215
