Yes, we were streaming for 24h about Liferay DXP and Liferay Portal 7.3 (and previous versions). All kinds of technical information that might be of interest for you. You might have missed it, but luckily we have it all recorded - and the recordings are available for you:
There's one aspect to cover before you can claim that your code is reusable: Actual reuse.
How can you achieve reuse of your application? By making it available where others can find and comfortably use it. And by making it available in many languages natively. Brian covers both of these aspects, their advantages and the traps that you can fall in to.