J2EE Application Migrations and Integrations

We were recently assisting a potential client in their evaluation for a possible migration of their current enterprise java application to a new(er) cloud application framework. 

Well, a good starting point we thought was to first figure out what's the logical comparison between the 2 architectures and to understand it's similarities and drawbacks.

If there are good routines, algos and rules already built and battle-tested  in the existing j2ee apps, we could explore reusing them rather than to rebuild them.

Now onto the POC phase :)