2) Minimum Walking Skeleton

http://alistair.cockburn.us/Walking+skeleton
If the core loop was focused on the business aspect of your product, the walking skeleton is focused on the tech! It’s the minimum architecture that links together the key building blocks of your system. It’s not meant to be your final architecture, its meant to show that at the most fundamental level you can make a coherent working system.

I often see examples where a tiny string of data is “passed around” the system. Its advantage is that you can then build out, tackling the riskiest or most worrying architectural features – for example adding authentication/authorisation. It’s a useful first target for the dev team as is it gives you the confidence that you have “something working” very early. The problem then becomes one of prioritisation!