Get Id of Items

My customized content types need a link passing its ID to another PHP script. This PHP script looks into database and performs based on the ID. Here is the sample page template:
<div tal:define="itemId context/getId;
itemIdUpper python: itemId.upper()">
<a href=""
tal:attributes="href python: 'http://another.site.com/some.php?k='+itemIdUpper;
title itemIdUpper;">Show in Another App</a>