Where to download SUN portlet tag library?

Hi,

We often write portlet jsp using tag library, as:

<%@ taglib uri="http://java.sun.com/portlet" prefix="portlet" %>

but now I need to download this tag library so that we can run some tests
without network, somehow I tried to search everywhere in Google but cannot
find, it would be great if you can give me a pointer?

Thanks very much for helps, Lisheng