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| <div class="titlepage"><div><div><h3 class="title"> |
| <a name="boost_asio.reference.StreamDescriptorService"></a><a class="link" href="StreamDescriptorService.html" title="Stream descriptor service requirements">Stream |
| descriptor service requirements</a> |
| </h3></div></div></div> |
| <p> |
| A stream descriptor service must meet the requirements for a <a class="link" href="DescriptorService.html" title="Descriptor service requirements">descriptor |
| service</a>, as well as the additional requirements listed below. |
| </p> |
| <p> |
| In the table below, <code class="computeroutput"><span class="identifier">X</span></code> denotes |
| a stream descriptor service class, <code class="computeroutput"><span class="identifier">a</span></code> |
| denotes a value of type <code class="computeroutput"><span class="identifier">X</span></code>, |
| <code class="computeroutput"><span class="identifier">b</span></code> denotes a value of type |
| <code class="computeroutput"><span class="identifier">X</span><span class="special">::</span><span class="identifier">implementation_type</span></code>, <code class="computeroutput"><span class="identifier">ec</span></code> |
| denotes a value of type <code class="computeroutput"><span class="identifier">error_code</span></code>, |
| <code class="computeroutput"><span class="identifier">mb</span></code> denotes a value satisfying |
| <a class="link" href="MutableBufferSequence.html" title="Mutable buffer sequence requirements">mutable buffer |
| sequence</a> requirements, <code class="computeroutput"><span class="identifier">rh</span></code> |
| denotes a value meeting <a class="link" href="ReadHandler.html" title="Read handler requirements"><code class="computeroutput"><span class="identifier">ReadHandler</span></code></a> requirements, <code class="computeroutput"><span class="identifier">cb</span></code> denotes a value satisfying <a class="link" href="ConstBufferSequence.html" title="Constant buffer sequence requirements">constant |
| buffer sequence</a> requirements, and <code class="computeroutput"><span class="identifier">wh</span></code> |
| denotes a value meeting <a class="link" href="WriteHandler.html" title="Write handler requirements"><code class="computeroutput"><span class="identifier">WriteHandler</span></code></a> requirements. |
| </p> |
| <div class="table"> |
| <a name="id858878"></a><p class="title"><b>Table 28. StreamDescriptorService requirements</b></p> |
| <div class="table-contents"><table class="table" summary="StreamDescriptorService requirements"> |
| <colgroup> |
| <col> |
| <col> |
| <col> |
| </colgroup> |
| <thead><tr> |
| <th> |
| <p> |
| expression |
| </p> |
| </th> |
| <th> |
| <p> |
| return type |
| </p> |
| </th> |
| <th> |
| <p> |
| assertion/note<br> pre/post-condition |
| </p> |
| </th> |
| </tr></thead> |
| <tbody> |
| <tr> |
| <td> |
| <p> |
| <code class="computeroutput"><span class="identifier">a</span><span class="special">.</span><span class="identifier">read_some</span><span class="special">(</span><span class="identifier">b</span><span class="special">,</span> |
| <span class="identifier">mb</span><span class="special">,</span> |
| <span class="identifier">ec</span><span class="special">);</span></code> |
| </p> |
| </td> |
| <td> |
| <p> |
| <code class="computeroutput"><span class="identifier">size_t</span></code> |
| </p> |
| </td> |
| <td> |
| <p> |
| pre: <code class="computeroutput"><span class="identifier">a</span><span class="special">.</span><span class="identifier">is_open</span><span class="special">(</span><span class="identifier">b</span><span class="special">)</span></code>.<br> |
| <br> Reads one or more bytes of data from a descriptor <code class="computeroutput"><span class="identifier">b</span></code>.<br> <br> The mutable buffer |
| sequence <code class="computeroutput"><span class="identifier">mb</span></code> specifies |
| memory where the data should be placed. The operation shall always |
| fill a buffer in the sequence completely before proceeding to the |
| next.<br> <br> If successful, returns the number of bytes read. |
| Otherwise returns <code class="computeroutput"><span class="number">0</span></code>. |
| If the total size of all buffers in the sequence <code class="computeroutput"><span class="identifier">mb</span></code> is <code class="computeroutput"><span class="number">0</span></code>, |
| the function shall return <code class="computeroutput"><span class="number">0</span></code> |
| immediately.<br> <br> If the operation completes due to graceful |
| connection closure by the peer, the operation shall fail with |
| <code class="computeroutput"><span class="identifier">error</span><span class="special">::</span><span class="identifier">eof</span></code>. |
| </p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p> |
| <code class="computeroutput"><span class="identifier">a</span><span class="special">.</span><span class="identifier">async_read_some</span><span class="special">(</span><span class="identifier">b</span><span class="special">,</span> |
| <span class="identifier">mb</span><span class="special">,</span> |
| <span class="identifier">rh</span><span class="special">);</span></code> |
| </p> |
| </td> |
| <td> |
| <p> |
| <code class="computeroutput"><span class="keyword">void</span></code> |
| </p> |
| </td> |
| <td> |
| <p> |
| pre: <code class="computeroutput"><span class="identifier">a</span><span class="special">.</span><span class="identifier">is_open</span><span class="special">(</span><span class="identifier">b</span><span class="special">)</span></code>.<br> |
| <br> Initiates an asynchronous operation to read one or more |
| bytes of data from a descriptor <code class="computeroutput"><span class="identifier">b</span></code>. |
| The operation is performed via the <code class="computeroutput"><span class="identifier">io_service</span></code> |
| object <code class="computeroutput"><span class="identifier">a</span><span class="special">.</span><span class="identifier">io_service</span><span class="special">()</span></code> |
| and behaves according to <a class="link" href="asynchronous_operations.html" title="Requirements on asynchronous operations">asynchronous |
| operation</a> requirements.<br> <br> The mutable buffer |
| sequence <code class="computeroutput"><span class="identifier">mb</span></code> specifies |
| memory where the data should be placed. The operation shall always |
| fill a buffer in the sequence completely before proceeding to the |
| next.<br> <br> The implementation shall maintain one or more |
| copies of <code class="computeroutput"><span class="identifier">mb</span></code> until |
| such time as the read operation no longer requires access to the |
| memory specified by the buffers in the sequence. The program must |
| ensure the memory is valid until:<br> <br> — the last copy of |
| <code class="computeroutput"><span class="identifier">mb</span></code> is destroyed, |
| or<br> <br> — the handler for the asynchronous operation is invoked,<br> |
| <br> whichever comes first. If the total size of all buffers |
| in the sequence <code class="computeroutput"><span class="identifier">mb</span></code> |
| is <code class="computeroutput"><span class="number">0</span></code>, the asynchronous |
| read operation shall complete immediately and pass <code class="computeroutput"><span class="number">0</span></code> as the argument to the handler |
| that specifies the number of bytes read.<br> <br> If the operation |
| completes due to graceful connection closure by the peer, the operation |
| shall fail with <code class="computeroutput"><span class="identifier">error</span><span class="special">::</span><span class="identifier">eof</span></code>.<br> |
| <br> If the operation completes successfully, the <code class="computeroutput"><span class="identifier">ReadHandler</span></code> object <code class="computeroutput"><span class="identifier">rh</span></code> is invoked with the number |
| of bytes transferred. Otherwise it is invoked with <code class="computeroutput"><span class="number">0</span></code>. |
| </p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p> |
| <code class="computeroutput"><span class="identifier">a</span><span class="special">.</span><span class="identifier">write_some</span><span class="special">(</span><span class="identifier">b</span><span class="special">,</span> |
| <span class="identifier">cb</span><span class="special">,</span> |
| <span class="identifier">ec</span><span class="special">);</span></code> |
| </p> |
| </td> |
| <td> |
| <p> |
| <code class="computeroutput"><span class="identifier">size_t</span></code> |
| </p> |
| </td> |
| <td> |
| <p> |
| pre: <code class="computeroutput"><span class="identifier">a</span><span class="special">.</span><span class="identifier">is_open</span><span class="special">(</span><span class="identifier">b</span><span class="special">)</span></code>.<br> |
| <br> Writes one or more bytes of data to a descriptor <code class="computeroutput"><span class="identifier">b</span></code>.<br> <br> The constant |
| buffer sequence <code class="computeroutput"><span class="identifier">cb</span></code> |
| specifies memory where the data to be written is located. The operation |
| shall always write a buffer in the sequence completely before proceeding |
| to the next.<br> <br> If successful, returns the number of |
| bytes written. Otherwise returns <code class="computeroutput"><span class="number">0</span></code>. |
| If the total size of all buffers in the sequence <code class="computeroutput"><span class="identifier">cb</span></code> is <code class="computeroutput"><span class="number">0</span></code>, |
| the function shall return <code class="computeroutput"><span class="number">0</span></code> |
| immediately. |
| </p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p> |
| <code class="computeroutput"><span class="identifier">a</span><span class="special">.</span><span class="identifier">async_write_some</span><span class="special">(</span><span class="identifier">b</span><span class="special">,</span> |
| <span class="identifier">cb</span><span class="special">,</span> |
| <span class="identifier">wh</span><span class="special">);</span></code> |
| </p> |
| </td> |
| <td> |
| <p> |
| <code class="computeroutput"><span class="keyword">void</span></code> |
| </p> |
| </td> |
| <td> |
| <p> |
| pre: <code class="computeroutput"><span class="identifier">a</span><span class="special">.</span><span class="identifier">is_open</span><span class="special">(</span><span class="identifier">b</span><span class="special">)</span></code>.<br> |
| <br> Initiates an asynchronous operation to write one or more |
| bytes of data to a descriptor <code class="computeroutput"><span class="identifier">b</span></code>. |
| The operation is performed via the <code class="computeroutput"><span class="identifier">io_service</span></code> |
| object <code class="computeroutput"><span class="identifier">a</span><span class="special">.</span><span class="identifier">io_service</span><span class="special">()</span></code> |
| and behaves according to <a class="link" href="asynchronous_operations.html" title="Requirements on asynchronous operations">asynchronous |
| operation</a> requirements.<br> <br> The constant buffer |
| sequence <code class="computeroutput"><span class="identifier">cb</span></code> specifies |
| memory where the data to be written is located. The operation shall |
| always write a buffer in the sequence completely before proceeding |
| to the next.<br> <br> The implementation shall maintain one |
| or more copies of <code class="computeroutput"><span class="identifier">cb</span></code> |
| until such time as the write operation no longer requires access |
| to the memory specified by the buffers in the sequence. The program |
| must ensure the memory is valid until:<br> <br> — the last copy |
| of <code class="computeroutput"><span class="identifier">cb</span></code> is destroyed, |
| or<br> <br> — the handler for the asynchronous operation is invoked,<br> |
| <br> whichever comes first. If the total size of all buffers |
| in the sequence <code class="computeroutput"><span class="identifier">cb</span></code> |
| is <code class="computeroutput"><span class="number">0</span></code>, the asynchronous |
| operation shall complete immediately and pass <code class="computeroutput"><span class="number">0</span></code> |
| as the argument to the handler that specifies the number of bytes |
| read.<br> <br> If the operation completes successfully, the |
| <code class="computeroutput"><span class="identifier">WriteHandler</span></code> object |
| <code class="computeroutput"><span class="identifier">wh</span></code> is invoked with |
| the number of bytes transferred. Otherwise it is invoked with |
| <code class="computeroutput"><span class="number">0</span></code>. |
| </p> |
| </td> |
| </tr> |
| </tbody> |
| </table></div> |
| </div> |
| <br class="table-break"> |
| </div> |
| <table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> |
| <td align="left"></td> |
| <td align="right"><div class="copyright-footer">Copyright © 2003 - 2010 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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