  </li>
<li class="listitem">
                An error occurs on the stream.
              </li>
</ul></div>
<p>
            This operation is implemented in terms of one or more calls to the next
            layer's <code class="computeroutput"><span class="identifier">async_read_some</span></code>
            and <code class="computeroutput"><span class="identifier">async_write_some</span></code>
            functions, and is known as a <span class="emphasis"><em>composed operation</em></span>.
          