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<title>Requirements on asynchronous socket operations</title>
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<div class="titlepage"><div><div><h3 class="title">
<a name="asio.reference.asynchronous_socket_operations"></a><a class="link" href="asynchronous_socket_operations.html" title="Requirements on asynchronous socket operations">Requirements
on asynchronous socket operations</a>
</h3></div></div></div>
<p>
In this library, <span class="emphasis"><em>asynchronous socket operations</em></span> are
those member functions having prefix <code class="computeroutput"><span class="identifier">async_</span></code>.
</p>
<p>
For an object <code class="computeroutput"><span class="identifier">s</span></code>, a program
may initiate asynchronous socket operations such that there are multiple
simultaneously outstanding asynchronous operations.
</p>
<p>
When there are multiple outstanding asynchronous <a class="link" href="read_write_operations.html" title="Requirements on read and write operations">read
operations</a> on <code class="computeroutput"><span class="identifier">s</span></code>:
</p>
<p>
— having no argument <code class="computeroutput"><span class="identifier">flags</span></code>
of type <code class="computeroutput"><span class="identifier">socket_base</span><span class="special">::</span><span class="identifier">message_flags</span></code>, or
</p>
<p>
— having an argument <code class="computeroutput"><span class="identifier">flags</span></code>
of type <code class="computeroutput"><span class="identifier">socket_base</span><span class="special">::</span><span class="identifier">message_flags</span></code> but where <code class="computeroutput"><span class="special">(</span><span class="identifier">flags</span> <span class="special">&</span> <span class="identifier">socket_base</span><span class="special">::</span><span class="identifier">message_out_of_band</span><span class="special">)</span>
<span class="special">==</span> <span class="number">0</span></code>
</p>
<p>
then the <code class="computeroutput"><span class="identifier">buffers</span></code> are filled
in the order in which these operations were issued. The order of invocation
of the completion handlers for these operations is unspecified.
</p>
<p>
When there are multiple outstanding asynchronous <a class="link" href="read_write_operations.html" title="Requirements on read and write operations">read
operations</a> on <code class="computeroutput"><span class="identifier">s</span></code> having
an argument <code class="computeroutput"><span class="identifier">flags</span></code> of type
<code class="computeroutput"><span class="identifier">socket_base</span><span class="special">::</span><span class="identifier">message_flags</span></code> where <code class="computeroutput"><span class="special">(</span><span class="identifier">flags</span> <span class="special">&</span> <span class="identifier">socket_base</span><span class="special">::</span><span class="identifier">message_out_of_band</span><span class="special">)</span>
<span class="special">!=</span> <span class="number">0</span></code>
then the <code class="computeroutput"><span class="identifier">buffers</span></code> are filled
in the order in which these operations were issued.
</p>
<p>
When there are multiple outstanding asynchronous <a class="link" href="read_write_operations.html" title="Requirements on read and write operations">write
operations</a> on <code class="computeroutput"><span class="identifier">s</span></code>, the
<code class="computeroutput"><span class="identifier">buffers</span></code> are transmitted in
the order in which these operations were issued. The order of invocation
of the completion handlers for these operations is unspecified.
</p>
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<div class="copyright-footer">Copyright © 2003-2023 Christopher M. Kohlhoff<p>
Distributed under the Boost Software License, Version 1.0. (See accompanying
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>)
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