IMO the best way to add a "business key" to a processInstance is by extending ProcessInstance (using the Hibernate subclass mechanism). Unfortunately, when I tried to do this in the past, I had issues with hibernate proxies, etc. The benefit of this approach (assuming the proxy issues could be resolved) is that the developer can extend ProcessInstance with whatever data type or however many business keys they deem appropriate, and then create hibernate queries as needed to support their requirement. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4017280#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...