[TYPO3-mvc] DDD approach for a questionnaire

[Pascal Jungblut]

Hello everybody,

I'm currently planning a rather big Extbase/Fluid extension and I'm wondering about the datastructures. The extension is organized as a questionnaire: there are like 15 steps, each one of these steps contains at least 10 questions that can be answered with yes or no. Depending on the answer, other questions like "If yes, when:" should pop up. My question is: how do I implement this the best way in a OOP and DDD manner? 

Would it be best to just make a model for each step (which is not very flexible) or should I store the steps in a session and persist it at the end of the questionnaire which would mean that a lot of Extbase features like validation could not be used? What do you guys think?

If this is too much meta-talk, let me know.

Thanks in advance
Pascal