Stack, as well as container may only have a dependency on the interfaces (SPI) not the implementation (framework). The framework code is an implementation detail that may not be available in all target containers. I know this sounds academic, and probably is not true at the moment, but proper decoupling requires this IMO. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4141593#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...