include CDATA in CDATA

Hello, excuse me for my bad english.

I am actually trying to display xml using docbook. To do this, I use:
<programlisting>
<![CDATA[
  my_text
]]>
</programlisting>

But if the text i want to insert contains itself a <![CDATA[ ...]]> tag, my method does not function.

Have you an other one?