[OBSOLETE] FAQ: An Overview of Using Custom Code in SmartThings (SmartThings Classic, Groovy Code)

Here you go:

CoRE and Piston Rules Engine, first design steps

If you use the magnifying glass in the upper right, you can search this thread or any thread.

EDIT: Here’s the GitHub (it’s in the thread above; https://github.com/ady624/CoRE)