to be set once. The callback is
        not reset after being called. The same callback is used for both synchronous
        and asynchronous reads. The callback is passive; in order to be called, a
        stream read operation must be active.
      </p>
<div class="note"><table border="0" summary="Note">
<tr>
<td rowspan="2" align="center" valign="top" width="25"><img alt="[Note]" src="../../../../../../doc/src/images/note.png"></td>
<th align="left">Note</th>
</tr>
<tr><td align="left" valign="top"><p>
 