ndler must be:
</p>
<pre class="programlisting">void handler(
  const boost::system::error_code&amp; error, // Result of operation.
  std::size_t bytes_transferred           // Number of bytes read.
);
</pre>
<p>
                Regardless of whether the asynchronous operation completes immediately
                or not, the handler will not be invoked from within this function.
                Invocation of the handler will be performed in a manner equivalent
                to using <code class="computer