eListener is registered with a <a href="../../javax/servlet/ServletOutputStream.html" title="class in javax.servlet"><code>ServletOutputStream</code></a>,
 this method will be invoked by the container the first time when it is possible
 to write data. Subsequently the container will invoke this method if and only
 if the <a href="../../javax/servlet/ServletOutputStream.html#isReady--"><code>ServletOutputStream.isReady()</code></a> method
 has been called and has returned a value of <code>false</code> and a 