Retrieve the param value from the URL inside the portlet

Hi All,We are having two pages namely P1 and P2. P1 has portlet A which display list of links. P2 has portlet B which display detail based on the value from the portlet A (in page P1). We are able to dynamically build the URL with the ID as querystring in the portlet A. We are unable to retrieve the passed value in the portlet B from the URL. Can anyone suggest a way to retrieve the value from the URL inside the portlet?